012-06263A
Instruction Manual
for the PASCO scientific
Model SF-9584A
10/96
LOW VOLTAGE AC/DC
POWER SUPPLY
LOW VOLTAGE AC/DC POWER SUPPLY
¨
V
A
10
VOLTAGE ADJUST
DC
+
–
0 – 24 V
12 14
8
16
18
6
20
CURRENT ADJUST
MAX DC CURRRENT
10 A
4
6A
12 V
24 V
OFF
AC
SF-9584A
2 24
ON
22
RESET
2-24 V
6 A MAX
© 1996 PASCO scientific
$5.00

¨
better
10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA
Phone (916) 786-3800 • FAX (916) 786-8905 • email: techsupp@PASCO.com
ways to
teach science
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
TO PREVENT THE RISK OF ELECTRIC SHOCK, DO NOT
REMOVE COVER ON UNIT. NO USER SERVICEABLE
PARTS INSIDE. REFER SERVICING TO QUALIFIED
SERVICE PERSONNEL.
The lightning flash with arrowhead, within
an equilateral triangle, is intended to alert
the user of the presence of uninsulated
“dangerous voltage” within the product’s
enclosure that may be of sufficient magnitude to constitute a risk of electric shock
to persons.
The exclamation point within an equilateral triangle is intended to alert the user
of the presence of important operating
and maintenance (servicing) instructions in the literature accompanying the
appliance.
012-06263A
Low Voltage AC/DC Power Supply
Table of Contents
Section
Page
Copyright, Warranty, and Equipment Return ...................................................... ii
Introduction ....................................................................................................... 1
Operation ....................................................................................................... 1 - 2
Equipment Specifications ................................................................................... 3
Schematics and Parts Lists ............................................................................. 5 - 12
Technical Support ................................................................................... Back Cover
i
Low Voltage AC/DC Power Supply
012-06263A
Copyright, Warranty and Equipment Return
Please—Feel free to duplicate this manual
subject to the copyright restrictions below.
Copyright Notice
Equipment Return
The PASCO scientific 012-06263A manual is copyrighted and all rights reserved. However, permission
is granted to non-profit educational institutions for
reproduction of any part of the Low Voltage AC/DC
Power Supply manual providing the reproductions are
used only for their laboratories and are not sold for
profit. Reproduction under any other circumstances,
without the written consent of PASCO scientific, is
prohibited.
Should the product have to be returned to PASCO
scientific, for whatever reason, notify PASCO scientific
by letter or phone BEFORE returning the product. Upon
notification, the return authorization and shipping instructions will be promptly issued.
Limited Warranty
When returning equipment for repair, the units must
be packed properly. Carriers will not accept responsibility for damage caused by improper packing. To be
certain the unit will not be damaged in shipment,
observe the following rules:
NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATION.
ä
PASCO scientific warrants the product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workmanship. The warranty does not cover damage to the
product caused by abuse or improper use. Determination of whether a product failure is the result of a
manufacturing defect or improper use by the customer
shall be made solely by PASCO scientific. Responsibility for the return of equipment for warranty repair
belongs to the customer. Equipment must be properly
packed to prevent damage and shipped postage or
freight prepaid. (Damage caused by improper packing
of the equipment for return shipment will not be
covered by the warranty.) Shipping costs for returning
the equipment, after repair, will be paid by PASCO
scientific.
➀ The carton must be strong enough for the item
shipped.
➁ Make certain there is at least two inches of packing
material between any point on the apparatus and the
inside walls of the carton.
➂ Make certain that the packing material can not
shift in the box, or become compressed, thus letting
the instrument come in contact with the edge of the
box.
Credits
Author:
Editor:
Hans Frederiksen
Sunny Bishop
ii
Address:
PASCO scientific
10101 Foothills Blvd.
P.O. Box 619011
Roseville, CA 95678-9011
Phone:
(916) 786-3800
FAX:
(916) 786-8905
email:
techsupp@PASCO.com
012-06263A
Low Voltage AC/DC Power Supply
Introduction
The Low Voltage AC/DC Power Supply is intended for
supervised classroom use.
The PASCO scientific Model SF-9584A Low Voltage
AC/DC Power Supply provides two outputs: a regulated
DC output and an unregulated AC output. The DC output can be delivered in two modes: constant voltage
mode and constant current mode.
Operation
DC Output, Limitations
DC Output Operation:
➀ Flip the power ON/OFF switch to OFF.
The DC output is regulated for both constant-voltage and
constant–current operation.
➁ Plug the power cord into a grounded outlet of the appropriate voltage :
Model SF-9584A, 115 V AC (78–130 V AC), 60 Hz
or
Model SF-9584A-230, 230 V AC (200 –242 V AC),
50 Hz.
Constant Voltage mode:
The voltage is continuously variable from 0 –24 V DC.
The maximum load drawn in the range from 0–12 V DC
is 10 A. In the 12 - 24 V range, a load of 10–6 A may be
drawn as the maximum load. At 24 V, the maximum is 6
A. (See the illustration printed on the front panel, “Max.
DC Current,” or Figure 1.)
➂ Connect the 0 –24 V DC OUTPUT terminals of the
power supply to the circuit. (Connecting wires are not
provided with the power supply.)
Constant Current mode:
The load may be varied from 1–10 A in the 1–12 V DC
range. At 12 V, the DC range is variable from 1–10 A.
At 24 V, the range decreases to 0–6 A. (See the illustration printed on the front panel, “Max. DC Current,” or
Figure 1.) A digital meter allows monitoring of both
voltage and current for the DC output.
➃ Rotate the DC VOLTAGE ADJUST knob and the DC
CURRENT ADJUST knob fully counterclockwise.
➄ Flip the power ON/OFF switch to ON. The switch
will light to show that the power supply is on.
➅ Constant Voltage Mode: Turn the DC CURRENT
ADJUST knob fully clockwise. Then adjust the DC
VOLTAGE ADJUST knob to obtain the desired output voltage, as indicated on the meter. The output current is displayed on the current meter.
MAX DC CURRRENT
➆ Constant Current Mode: Turn the DC VOLTAGE
10 A
ADJUST knob fully clockwise. Adjust the DC CURRENT ADJUST knob to obtain the desired output
current, as indicated on the meter. The output voltage
is displayed on the voltage meter.
6A
12 V
24 V
Figure 1. Maximum DC Current
1
Low Voltage AC/DC Power Supply
012-06263A
AC Output Operation:
AC Output Limitations
➀ Flip the power ON/OFF switch to OFF.
The AC output is unregulated and is adjustable in 2-V
increments from 2 to 24 V AC, with a maximum output current of 6 amperes. This output is protected by
a 6-amp circuit breaker. If the maximum current output is exceeded, the circuit breaker button below the
power switch will pop out. (See Figure 2.)
➁ Plug the power cord into a grounded outlet of the appropriate voltage :
Model SF-9584A, 115 V AC (78 - 130 V AC), 60 Hz
or
Model SF-9584A-230, 230 V AC (200 - 242 V AC),
50 Hz.
➂ Connect the 2–24 V AC OUTPUT terminals of the
power supply to the circuit. (Connecting wires are not
provided with the power supply.)
OFF
AC
10
➃ Rotate the AC VOLTAGE ADJUST knob to the
12 14
8
2–V position.
20
6
4
➄ Flip the power ON/OFF switch to ON. The switch
2 24
2-24 V
6 A MAX
will light to show that the power supply is on.
power switch
16
18
ON
22
RESET
circuit breaker
button
➅ Set the AC VOLTAGE ADJUST knob to the desired
setting.
Figure 2. Location of Circuit Breaker Button
The circuit breaker can be reset by simply pushing the
button back in. It may be necessary to reduce the AC
output voltage or the load connected to the AC output in
order to resume operation.
NOTE: If at any time the power supply fails to
come on, or if it shuts down during operation due to
excessive current, check the following: If the
ON/OFF switch does not light when unit is plugged
into the appropriate power source and the switch is
turned ON, check the fuse on the back of the unit.
If it is blown, replace it only with a similarly rated
fuse (Model SF-9584A— 8A Slo-Blo fuse, Model
SF-9584A-230— 4A Slo-Blo fuse).
ä
2
012-06263A
Low Voltage AC/DC Power Supply
Equipment Specifications
Specifications:
Outputs:
Ripple and Noise:
Less than 25 mV pp on DC output.
DC: regulated for both constant–voltage and constant–current operation. Both current and voltage continuously variable over the range 0–24 V DC and 0–10
amperes maximum. Independent floating ground reference.
Metering:
DC voltage and DC current
Accuracy is +1% ± 2 L.S.D.
Line Voltage Requirement:
78–130 V AC, 60 Hz (model SF-9584A)
200–242 V AC, 50 Hz (model SF-9584A - 230)
AC: 2 to 24 V (rms) AC, unregulated, selectable in
2–V increments, current up to 6 amperes. Output protected from overload by a 6-amp thermally-activated circuit breaker. Independent floating ground reference.
Power Requirement:
DC and AC: Maximum 350 W
DC only: Maximum 175 W
AC only: Maximum 175 W
NOTE: Both DC and AC outputs are available
simultaneously on separate floating output terminals.
Either one of the DC output terminals can be connected to either one of the AC output terminals to
form a composite signal without damage to the unit.
ä
Fuse:
8 A Slo-Blo—(model SF-9584A)
4 A Slo-Blo—(model SF-9584A-230)
Line Regulation:
Size:
Less than 1% change in DC output voltage or current for full range change in line voltage. AC output not regulated.
118 x 298 x 229 mm (H x W x D including controls)
Load Regulations:
Better than 1% no-load to full-load on the DC output voltage or current. AC output not regulated.
3
Low Voltage AC/DC Power Supply
012-06263A
Notes:
4
012-06263A
Low Voltage AC/DC Power Supply
Schematics and Parts Lists
ä
Caution: If repairs are needed, they should be performed only by experienced personnel.
Figure 2. Schematic Overview
5
Low Voltage AC/DC Power Supply
012-06263A
Figure 3. Main Board
6
012-06263A
Low Voltage AC/DC Power Supply
Parts List – Main Board
Item
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
Reference
R201
R204R206
R220-221
R205
R216 R219
R211 R214 R217
R227
R228
R218 R223
R226
R207 R230
R212
R213 R229
R222
R202-203 R208
R224
R210 R215
TR201-202
TR203-205
C229-234 C243-244
C213 C215 C235
C237-238 C240-241
C224-227
C214 C216-223
C228 C239
C211-212
C207-210 C236
C201-205
C206
D203
D205-209
D201-202
D210
Q205
Q203
Q202
Q201
Q204
U204
U201
U202
U205
U207
U206
RE201-202
J202-208
J200
J213
Part Name
Value
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
TRIMPOT HORIZ
TRIMPOT HORIZ
CERAMIC CAP
CERAMIC CAP
4K7
10K
10K
47K
100K
100R
150R
390R
470R
680R
IK0
4K7
10K
100K
180K
IM0
0.01R
220R
10K
1.0nF
10nF
250V
250V
250V
250V
250V
250V
250V
250V
250V
250V
250V
250V
250V
250V
250V
250V
20mV
250V
250V
63V
63V
STACK FOIL CAP
STACK FOIL CAP
100nF
100nF
STACK FOIL CAP
ELECTROLYT CAP
ELECTROLYT CAP
ELECTROLYT CAP
DIODE
DIODE
DIODE
ZENER-DIODE
NPN TRANSISTOR
PNP TRANSISTOR
NPN TRANSISTOR
Nch MOSFET
Nch MOSFET
DualOpAmp
IC
VOLTAGE REGULATOR
VOLTAGE REGULATOR
VOLTAGE REGULATOR
RAIL SPLITTER
RELAY 5V
CONNECTOR
3M-929 20 PIN
STOCKO MKS4
470nF
4.7UF
100UF
1000UF
BYV27-200
lN4148
2W04M
BZX79-C2V7
BC547B
BC557B
BC639
BUK456-60A
BS170
LTll12
LM614
LM317
LM78L05
LM7805
TLE2426CLP
M4-5H
6.3 MM
20 PIN
4 PIN
7
Qty Stock No.
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
2W
0.lW
0.lW
1
2
2
1
2
3
1
1
2
1
2
1
2
1
3
1
2
2
3
8
7
601074
601082
601083
601099
601106
6030701
6030801
6031051
6031101
6031201
6031301
6031701
6031901
6032501
6032651
6033101
604301
605935
605960
611890
612010
400V
63V
4
11
613170
613450
63V
25V
63V
35V
200V
75V
400V
2.7V
50V
50V
100V
60V
60V
30V
36V
40V
35V
35V
40V
125V/30W
2
5
5
1
1
5
2
1
1
1
1
1
1
1
1
1
1
1
1
2
7
1
1
613530
615643
615785
616003
623267
623300
623665
624060
624710
624720
624750
625690
626120
630211
631214
632130
632430
632533
634941
637428
641245
641321
641357
2A
0.2A
2A
0.5W
0.lA
0.2A
1.5A
52A
0.5A
10mA
0.3mA
lA
0.1A
1.5A
0.08A
1A
Low Voltage AC/DC Power Supply
012-06263A
Figure 4. Display Unit
8
012-06263A
Low Voltage AC/DC Power Supply
Parts List – Display Unit
Item Reference
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
30
R101 R111
R107-108
R117-118 R120
R103 R113
R104 R114
R100 R102
R105-106 R110
R112 R115-116
P1-2
C103 C123
C112 C132
C109-110
C129-130
C102 C104
C106-10 C111
C122 C124
C126-128 C131
C105 C125
C101 C121
D101-102
DS101-108
D103-104
D105-106
U102 U104
U101 U103
SW101
J102-103
J101
U101 U103
Part Name
Value
Qty Stock No.
RESISTOR
RESISTOR
330R
1K0
250V
250V
0.4W
0.4W
2
5
6031001
6031301
RESISTOR
RESISTOR
RESISTOR
6K8
47K
100K
250V
250V
250V
0.4W
0.4W
0.4W
2
2
8
6031801
6032301
6032501
POTMETER
CERAMIC CAP
CERAMIC CAP
CERAMIC CAP
10K
100pF
1.0nF
10nF
300V
63V
63V
63V
1.5W
2
2
2
4
608251
611770
611890
612010
STACK FOILCAP
100nF
63V
12 613450
STACK FOIL CAP
ELECTROLYT CAP
LED
DISPLAY
DIODE
DIODE
VOLTAGE REF.
IC
SWITCH LOCKING
HEADER
3M-929
TULIPAN
470nF
100UF
HLMP-1719
HDSP-5301
1N4148
1N4007
LM385
ICL7107
MK2
16 PIN
20 PIN
SOK
63V
25V
2V
2V
75V
700V
20mA
9V
120V
500V
20 PIN
40 PIN
2
2
2
8
2
2
2
2
1
2
1
2
9
2mA
20mA
0.2A
1A
250mA
2.5A
613530
616440
622000
622940
623300
623390
631185
635057
638031
641029
641321
635539
Low Voltage AC/DC Power Supply
012-06263A
Figure 5. Switch-Mode Regulator
10
012-06263A
Low Voltage AC/DC Power Supply
Parts List – Switch-Mode Regulator
Item Reference
Part Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
RESISTOR
CERAMIC CAP
CERAMIC CAP
CERAMIC CAP
STACK FOIL CAP
STACK FOIL CAP
ELECTROLYT CAP
ELECTROLYT CAP
ELECTROLYT
DIODE
ULTRA FAST DIODE
DIODE
DIODE BRIDGE
ZENER-DIODE
ZENER-DIODE
NPN TRANSISTOR
Pch MOSFET
IC
R3
Rl-2
R14
R10 R12
R9
R8
R5
R7
R4 R13
R6
Rll
CI2 C14 C19
Cll
C7-8 C13
C17-18
C2-4 C15
C9-10
C5-6 C16
Cl
Dl
D2
D4-7
D10
D9
D8
Q2-3
Ql
Ul
Value
2K2
10K
0R
10R
100R
470R
3K3
4K7
47K
IK0
0.01R
1.0nF
4.7nF
10nF
100nF
470nF
2.2UF
100UF
CAP
BYV27-200
BYV79-100
lN4007
PBU802
BZV85-C15
BZV85-C33
BC639
SMP40P06
LM3524
11
250V
250V
250V
250V
250V
250V
250V
250V
250V
500V
20mV
63V
63V
63V
400V
63V
63V
63V
6800UF
200V
100V
700V
100V
15V
33V
100V
60V
40V
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
0.4W
1.6W
2W
63V
2A
14A
lA
8A
1.0W
1.0W
1.5A
40A
Qty
Stock No.
1
2
1
2
1
1
1
1
2
1
1
3
1
3
2
4
2
3
1
1
1
4
1
1
1
2
1
1
601066
601083
6020901
6030101
6030701
6031101
6031601
6031701
6032301
603810
604301
611890
611970
612010
613170
613530
615622
615785
616102
623267
623268
623390
623685
624515
624533
624750
626110
632350
Low Voltage AC/DC Power Supply
012-06263A
Figure 6. Filter Board
Parts List – Filter Board
Item Reference
Part Name
1
2
STACK FOIL CAP
H1-4
C301-303
Value
100NF
12
Qty
400V
4
3
Stock No.
613170
012-06263A
Low Voltage AC/DC Power Supply
Technical Support
Feedback
Contacting Technical Support
If you have any comments about the product or manual,
please let us know. If you have any suggestions on alternate experiments or find a problem in the manual, please
tell us. PASCO appreciates any customer feedback.
Your input helps us evaluate and improve our product.
Before you call the PASCO Technical Support staff, it
would be helpful to prepare the following information:
➤ If your problem is computer/software related, note:
­ Title and revision date of software;
To Reach PASCO
­ Type of computer (make, model, speed);
For technical support, call us at 1-800-772-8700 (toll-free
within the U.S.) or (916) 786-3800.
­ Type of external cables/peripherals.
fax:
➤ If your problem is with the PASCO apparatus, note:
(916) 786-3292
­ Title and model number (usually listed on the label);
e-mail: techsupp@PASCO.com
web:
­ Approximate age of apparatus;
www.pasco.com
­ A detailed description of the problem/sequence of
events. (In case you can’t call PASCO right away,
you won’t lose valuable data.);
­ If possible, have the apparatus within reach when
calling to facilitate description of individual parts.
➤ If your problem relates to the instruction manual, note:
­ Part number and revision (listed by month and year
on the front cover);
­ Have the manual at hand to discuss your questions.
13
012-05783A
2/95
$1.00
Instruction Sheet
for the PASCO
Model CI-6552A
POWER AMPLIFIER II
CAUTION!
CI-6552A
PLIFIER II
POWER AM
T
PU
L OUT
SIGNA
CI-6552A
II
LIFIER
R AMP ION!
POWE
CAUT
ON
0 V
0 to ±1
AX
1AM
IS ON ED.
LIGHT
RT
WHEN IS DISTO
DE!
FORM
WAVE
AMPLITU
EASE
DECR
Introduction
Filter Select Switch
The PASCO CI-6552A Power Amplifier II is an accessory to the PASCO Signal Interfaces, Series 6500 and
Mac65. It amplifies the output of the computer, allowing
it to be used as a controlled DC power source or an AC
function generator.
The CI-6552A Power Amplifier II has a filter select
switch which is preset for use with the CI-6560 Signal
Interface II (Mac65). The bandwidth at that switch position is about 100KHz, limited by the power amplifier’s
feedback compensation section and the load. When using
the Power Amplifier II with the CI-6510 Signal Interface
(Series 6500), the bandwidth needs to be limited to
1.5KHz. To change the switch position push the filter select switch in the back panel slot to the left, as shown in
the illustration below.
With the Power Amplifier II plugged into one of the analog channels of the Signal Interface, the appropriate software (Power Amplifier for DOS, Power Amplifier for
APPLE II, or Science Workshop) can be used to generate
the following types of waves (up to ±10V peak at 1A, up
to 5,000 Hz):
Switch position
for CI-6510
Signal Interface
• sine,
• square,
Switch position
for CI-6560
Signal Interface II
• triangle, and
• sawtooth.
This means the computer can now be used as an AC signal generator to power external circuits while it monitors
its own output current as well as other inputs. The Science
Workshop software can also generate a DC output.
© 1995 PASCO scientific
This instruction edited by Robert Morrison
better
10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA
Phone (916) 786-3800 • FAX (916) 786-8905 • email: techsupp@PASCO.com
ways to
teach physics
Power Amplifier II
012-05783A
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return shipment will not be covered by the warranty.) Shipping costs
for returning the equipment, after repair, will be paid by
PASCO scientific.
Using Power Amplifier II
To install the Power Amplifier II, plug in its power cord
and plug the DIN plug into Channel A, B, or C of the appropriate PASCO Signal Interface box (CI-6510 or
CI-6560).
Equipment Return
➤ NOTE: Using Power Amplifier II with Series
6500, the Power Amplifier program is calibrated for
channel C. The Power Amplifier II can also be
plugged into Channel A or B but these channels are
not automatically calibrated to read the current as is
Channel C.
Should this product have to be returned to PASCO scientific, for whatever reason, notify PASCO scientific by letter or telephone BEFORE returning the product. Upon
notification, the return authorization and shipping instructions will be promptly issued.
To use the output of the Power Amplifier II, connect the
load to the banana jacks on the front of the Power Amplifier II. There is a power switch on the back left hand corner of the Power Amplifier II.
➤NOTE: NO EQUIPMENT WILL BE ACCEPTED FOR RETURN WITHOUT AN AUTHORIZATION.
➤ WARNING! Do not turn on the power switch
until a program (either Power Amplifier, Data
Monitor or Science Workshop) has been run and the
desired output voltage has been selected.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
When the computer is in DOS, the Power Amplifier
will output 10 Volts if the power switch is on and
this could overload a circuit that might be connected to it. The software controls this voltage:
The Data Monitor Program sets the default voltage
to zero and the Power Amplifier Program sets the
default AC peak voltage to 5 Volts.
CAUTION:
TO PREVENT THE RISK OF ELECTRIC SHOCK, DO
NOT REMOVE COVER ON UNIT. NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
When the Power Amplifier II is operating, a green power
indicator light on the front panel of the Power Amplifier
II will be lit. There is also a red current overload light
which comes on whenever the maximum current of 1 A is
exceeded. If this warning light is on, the waveform is distorted and you should reduce the output voltage.
The lightning flash with arrowhead, within
an equilateral triangle, is intended to alert
the user of the presence of uninsulated
“dangerous voltage” within the product’s
enclosure that may be of sufficient magnitude to constitute a risk of electric shock to
persons.
Limited Warranty
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workmanship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
The exclamation point within an equilateral triangle is intended to alert the
user of the presence of important operating and maintenance (servicing) instructions in the literature accompanying the appliance.
2
012-03175E
3/93
Instruction Manual and
Experiment Guide for
the PASCO scientific
Model ES-9054B
ELECTROMETER
FUNCTION
B1 B2
3
D
C
10
V
O
L
T
S
30
100
Model ES-9054B ELECTROMETER
ZERO
POWER
scientific
OFF
OUTPUT
© 1987 PASCO scientific
GND
INPUT
ADJUST
PUSH
TO
ZERO
ON
ZERO
LOCK
$7.50
012-03175E
Electrometer
Table of Contents
Section
Page
Copyright and Warranty ..................................................................................ii
Equipment Return ...........................................................................................ii
Introduction ..................................................................................................... 1
Operation ......................................................................................................... 1
Setup .......................................................................................................... 2
Measuring Charge ..................................................................................... 3
Measuring Voltage .................................................................................... 4
Measuring Current .................................................................................... 4
Using a Projection Meter .......................................................................... 5
Maintenace ...................................................................................................... 5
Battery Installation .................................................................................... 6
MOS-FET Replacement ............................................................................ 6
Schematic ........................................................................................................ 7
Parts List.......................................................................................................... 8
Technical Support ............................................................... Inside Back Cover
i
Electrometer
012-03175E
Copyright, Warranty, and Equipment Return
Please—Feel free to duplicate this manual
subject to the copyright restrictions below.
Copyright Notice
Equipment Return
The PASCO scientific 012-0xxxy Model Name manual
is copyrighted and all rights reserved. However,
permission is granted to non-profit educational institutions for reproduction of any part of the manual
providing the reproductions are used only for their
laboratories and are not sold for profit. Reproduction
under any other circumstances, without the written
consent of PASCO scientific, is prohibited.
Should the product have to be returned to PASCO
scientific for any reason, notify PASCO scientific by
letter, phone, or fax BEFORE returning the product.
Upon notification, the return authorization and shipping instructions will be promptly issued.
ä NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATION FROM PASCO.
Limited Warranty
PASCO scientific warrants the product to be free from
defects in materials and workmanship for a period of
one year from the date of shipment to the customer.
PASCO will repair or replace at its option any part of
the product which is deemed to be defective in material
or workmanship. The warranty does not cover damage
to the product caused by abuse or improper use.
Determination of whether a product failure is the result
of a manufacturing defect or improper use by the
customer shall be made solely by PASCO scientific.
Responsibility for the return of equipment for warranty
repair belongs to the customer. Equipment must be
properly packed to prevent damage and shipped
postage or freight prepaid. (Damage caused by improper packing of the equipment for return shipment
will not be covered by the warranty.) Shipping costs
for returning the equipment after repair will be paid by
PASCO scientific.
ii
When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing. To be certain
the unit will not be damaged in shipment, observe the
following rules:
➀ The packing carton must be strong enough for the
item shipped.
➁ Make certain there are at least two inches of packing material between any point on the apparatus and
the inside walls of the carton.
➂ Make certain that the packing material cannot shift
in the box or become compressed, allowing the
instrument come in contact with the packing carton.
Address:
PASCO scientific
10101 Foothills Blvd.
Roseville, CA 95747-7100
Phone:
FAX:
email:
web:
(916) 786-3800
(916) 786-3292
techsupp@pasco.com
www.pasco.com
012-03175E
Introduction
The Model ES-9054B Electrometer is an infinite
impedance (1014 ý) voltmeter that can be used for
direct measurements of voltage, and indirect measurements of current and charge. Because of its high
impedance, it is especially suited for measuring charge
in electrostatic experiments. It has a sensitivity nearly
1,000 times that of a standard, gold-leaf electroscope,
it has a center-zero meter that directly indicates charge
polarity, and it measures charges as low as 10-11
coulombs.
With these features, you’ll find that your electrostatics
demonstrations and labs are easier to perform and, with
quantitative data, are more informative as well.
The electrometer is battery powered by two 9 volt
batteries, and comes complete with the batteries and a
shielded test lead. Instructions for inserting the
batteries are at the end of this manual.
Operation
äIMPORTANT:
The controls on the front panel of the electrometer are
explained in Figure 1. Whether you’re using the
electrometer to measure voltage, current, or charge, the
following procedure should be followed each time you
turn on the electrometer. More information on making
accurate measurements is given in the sections that
follow.
① Never use the Electrometer for measuring
potentials in excess of 100 volts.
② Never connect the electrometer to an electrostatic generator such as a Van de Graff generator
or a Wimshurst machine.
③ Never touch the input leads until you have
grounded yourself to an earth ground. A person
walking across a rug on a cool, dry day can easily
pick up a potential of several thousand volts.
1
012-03175E
Mechanical zero adjust screw
(adjust with power off)
FUNCTION
B1 B2
3
D
C
10
V
O
L
T
S
30
100
Select voltage range
(3, 10, 30, or 100
volts full scale) or
test batteries
(B1 and B2)
Model ES-9054B ELECTROMETER
ZERO
POWER
scientific
OFF
OUTPUT
GND
INPUT
ADJUST
PUSH
TO
ZERO
ON
ZERO
LOCK
Zero meter (zero
switch should be in
ZERO LOCK position)
Zero Switch: In PUSH TO ZERO
setting, pushing knob will
discharge the electrometer
Connect test lead here
Connect to earth ground
0-3.6 volts for driving
a projection meter
Figure 1 Front Panel Controls
Setup
① Before turning on the electrometer, check that the
meter reads zero. If not, turn the Mechanical Zero
Adjust screw, located just below the meter face, until it does.
② Slide the POWER switch to the ON position.
③ Check the batteries:
a. Turn the FUNCTION switch to B1. The meter
pointer should read to the left of the B1 line at
the bottom of the meter face. If the pointer falls
within the area labeled B1, see the battery replacement section at the end of this manual.
b. Turn the FUNCTION switch to B2. The meter
pointer should read to the right of the B2 line at
the bottom of the meter face. If the pointer falls
within the area labeled B2, see the battery replacement section at the end of this manual.
④ Zero the meter:
a. Turn the FUNCTION switch to 3.
b. Turn the Zero Switch to the ZERO LOCK setting.
c. Adjust the ZERO ADJUST knob so the meter
reads zero volts.
⑤ Turn the Zero Switch to the PUSH TO ZERO setting.
⑥ Connect the test lead to the INPUT connector of the
electrometer.
⑦ Connect the GND post of the electrometer to an
earth ground.
charge or voltage. Set the FUNCTION switch to the
desired voltage range. The range setting refers to the
voltage input required to produce a full-scale meter
deflection (e.g., a setting of 30 means that a full scale
meter deflection indicates a voltage of 30 volts).
Important Points for General Operation:
① Between measurements, always press the Zero
Switch to discharge all current from the electrometer. (The Zero Switch must be in the PUSH TO
ZERO setting.) Shorting the test leads together is
insufficient. There may still be stray charges
within the electrometer circuitry.
② When adjusting the zero point of the electrometer, always turn the Zero Switch to the ZERO
LOCK position.
③ For good results, it is essential that the electrometer be connected to an earth ground (a water
pipe or the ground wire from a 120 VAC socket).
Only an earth ground provides a sufficient drain
for excess charges that may build up during an
experiment. It is also helpful if the experimenter is
grounded. Just touch one hand to a good earth
ground while, or just before, making measurements.
ä
You’re now ready to use the electrometer to measure
2
012-03175E
Measuring Charge by Induction
Under most conditions, the best way to measure charge
is by induction, using a proof plane and a Faraday ice
pail such as those included with PASCO’s Demonstration Electrostatics System. The proof plane is simply a
small conductive disk on an insulating handle. You
can make your own ice pail by mounting a conductive
cylinder on an insulating support, and placing a larger
conductive cylinder around it as a shield. Connect the
test lead of the electrometer probe to the inside cylinder, and connect the ground lead to the outside cylinder
(see Figure 4).
Measuring Charge
Charge measurement with the electrometer is indirect,
but simple. It is based on the relationship Q = CV,
where
Q and V are the charge and voltage across a capacitor
and C is the capacitance. The electrometer can be
thought of as an infinite impedance voltmeter in
parallel with a capacitor, as shown in Figure 2. The
capacitor represents the internal capacitance of the
Q = CV
Q
Voltmeter
V
–Q
Internal Capacitance of
Electrometer
C
(30-35 pf without Test
Probe; approximately
150 pf with Test Probe)
Electrometer
Proof Plane
Ground lead
Figure 2 Ideal Schematic of the Electrometer
electrometer, plus the capacitance of the leads.
When a charge is placed across the Electrometer leads,
a voltage V will read on the meter. If the value C is
known, the value of the charge can be calculated as
Q = CV. However, when you touch the Electrometer
leads to another object to test a charge, the capacitance
may change. If the object adds significant capacitance,
the situation becomes as shown in Figure 3. The new
capacitance (C + Cext) must be determined to accurately
calculate the charge from the measured voltage.
Faraday ice pail
Figure 4 Using a Faraday Ice Pail
To sample the charge distribution on a charged object,
simply touch it with the proof plane, then place the
proof plane inside the inner cylinder of the ice pail,
without touching the cylinder. A charge is induced on
the inside cylinder that is equal but opposite to that on
the proof plane. You can now read the voltage on the
electrometer. By always using the proof plane and the
ice pail, the capacitance will be the same for all your
measurements and the charge on the proof plane will
always be proportional to the voltage reading of the
electrometer. However, in experiments for which you
want to know the absolute charge on the proof plane,
you need to know the total capacitance of the electrometer, plus the test probe, plus the ice pail with the proof
plane inside it. Fortunately, this is easily measured, as
described below. Once you know the capacitance,
you can calculate the absolute charge for any measurement as Q = CV.
Q + Q' = (C + Cext) V
Voltmeter
Q'
Q
V
Cext
C
–Q
Test lead
–Q'
Capacitance of object
connected to the
Electrometer
Figure 3 Change in Capacitance Due to
Charged Object
3
012-03175E
To measure the total capacitance:
inside cylinder of the ice pail, the Electrometer reading will
generally remain relatively unchanged. This is because the
total capacitance is only negligibly affected by the proof
plane. This may not always be the case, however.
① Turn on the Electrometer and zero the meter. Clip
the test lead of the probe to the inside cylinder of
your ice pail and the ground lead to the outside cylinder (see Figure 4).
② Use a DC power supply or a statically charged object to charge your proof plane.
③ Place the proof plane inside the inner cylinder of the
ice pail and adjust the FUNCTION switch to get a
meter reading near full scale. (For convenience, you
may want to touch the proof plane to the inside of
the ice pail and then remove the proof plane. The
effect on the voltage reading should be negligible.)
Record the voltage as Ve. Do not discharge the
Electrometer.
④ Take a capacitor of known capacitance, Ck. Ground
the leads of the capacitor to be sure it is fully discharged, then connect the capacitor between the inner and outer cylinder of the ice pail. With the
proof plane still inside the ice pail, record the meter
reading as Vk.
⑤ The capacitance of the Electrometer, Ce, can now be
calculated as:
Ce = CkVk/(Ve -Vk).
In general, contact measurements can be carried out in
much the same way as inductive measurements using
the ice pail. Touch the object with the test probe,
record the voltage V, and use Q = CV to calculate the
charge. However, if you suspect the object for which
you are measuring the charge appreciably affects the
total capacitance of the system, you will need to
remeasure the capacitance as described above.
Measuring Voltage
Voltage can be measured as with any voltmeter.
Connect the leads to the circuit, set the range (3, 10,
30, or 100 volts full scale), and read the voltage on the
meter.
Measuring Current
The Electrometer can be used for indirect current
measurements in many situations, though it is no
substitute for a good ammeter. Connect the Electrometer leads across a known resistance in the circuit and
measure the voltage. Use Ohm’s law (Voltage =
Current x Resistance) to determine the current. The
effect of the Electrometer on the circuit will be negligible in most circuits due to its exceedingly high input
impedance. However, the voltage drop across the
resistor must be within the voltage range of the Electrometer.
EXPLANATION: This measurement is
shown schematically in Figure 3. First the
Electometer is charged with an unknown charge
Q, that must satisfy the equation Q = CeVe, where
Ce is the total capacitance of the system and Ve is
the Electrometer reading. Then the second
capacitor is connected in parallel with the capacitance of the Electrometer. The total capacitance
is now Ce + Ck. The charge Q has not changed,
but now satisfies the equation
Q=
(Ce + Ck)Vk, where Vk is the new Electrometer
reading. Combining the two equations gives,
CeVe = (Ce + Ck)Vk, or Ce = CkVk/(Ve -Vk).
ä
If it is not convenient to hook the Electrometer across a
known resistance in the circuit, a precision resistor can
be connected between the input leads of the Electrometer. The circuit can then be broken, as for connection
to a standard ammeter, and connected in series with the
precision resistor. Again, measure the voltage across
this resistor and calculate the current. (The problem
with this technique is that the resistance must be high
enough so the voltage drop is easily measured, but low
enough so it doesn't significantly affect the current
through the circuit.)
If you want to use the Electrometer with a different set
of test leads, or a different ice pail, or even a different
proof plane, the capacitance may be different, and you
will need to repeat the above procedure to measure the
new capacitance.
Using a Projection Meter
The OUTPUT connectors on the ES-9054B Electrometer provide an output signal for driving a projection
meter, oscilloscope, or other monitoring device. The
output is proportional to meter deflection (within 10%)
with a
±3.6 VDC output corresponding to a full scale deflection. (The OUTPUT voltage depends only on meter
deflection. It is independent of the range setting of the
FUNCTION switch.)
ä NOTE: The capacitance of the Electrometer
is 30-35 pf. With the test probe, the total capacitance is approximately 150 pf. For best results,
measure the total capacitance.
Measuring Charge by Contact
Charges can also be measured by contact. You’ll find, for
example, that if you touch the charged proof plane to the
4
012-03175E
② Turn the ZERO ADJUST knob until the meter on
the Electrometer reads as close to full scale as
possible (either postive or negative).
③ Adjust the CALIBRATE knob on the Projection
Meter so that the Projection Meter reads the same
as the Electrometer.
④ Turn the ZERO ADJUST knob until the Electrometer and the Projection Meter read zero.
PASCO’s Model ES-9065 Projection Meter can be
used with an overhead projector to display the Electrometer readings for the whole class. The Projection
Meter connects directly to the OUTPUT jacks, red to
red and black to black.
To calibrate the Projection Meter:
① Set the FUNCTION switch to 3, and the Zero
Switch to ZERO LOCK.
Maintenance
Checking Out Your Electrometer
CAUTION: Whenever you open your
Electrometer, do not touch any of the components on the printed circuit board other than the
battery holders or the trim potentiometers. The
printed circuit contains the high impedance
MOS-FET input which can be damaged just by
touching the wrong lead.
ä
① Follow the setup instructions on pages 2-3 of this
manual to check the batteries and zero the Electrometer. If the batteries are low, see “Battery Installation.” If the meter cannot be zeroed, see
“MOS-FET Replacement.”
② Calibration Test: Set the FUNCTION switch to
30 and connect the input to an accurate 30 VDC
source. If the meter does not read 30 volts ±5%,
see “Calibration.”
Battery 1 (B1)
Battery 2 (B2)
③ Input Impedance Test: Set the FUNCTION
switch to 30 and connect the input to a 30 VDC
source. Disconnect the input cable at the front
panel input connector. Record the meter reading
and the time. If the input impedance is sufficient, it
will take 15 minutes or longer for the meter reading
to decrease to 30% of its initial value. If the input
impedance is low, see “Repairs.”
④ Zero Drift Test: With the meter zeroed, short the
leads of the input cable together. Turn the Zero
Switch to PUSH TO ZERO and depress the knob,
then release it. The meter should read zero volts
and should drift by no more than 75 mV/minute.
At any time, depressing the Zero Switch should
bring the meter immediately back to zero. If the
zero drift is excessive, see “Repairs.”
MOS-FET
Calibration
Potentiometer
Zero Calibration
Potentiometer
Figure 5 Inside the Electrometer
Battery Installation
To install or replace the batteries, remove the four
screws that fasten the front panel to the case, then
gently lift the front panel out of the case. Install the
batteries as shown in Figure 5. When removing and
installing the batteries, be careful not to bend the
battery clips or pull the battery wires out of the circuit
board. Place the new batteries in the clips with the
positive terminal closest to the printed circuit
board.Before replacing the front panel, test that the
batteries are good and the connections are secure by
flipping the FUNCTION switch first to B1 and then to
B2. The meter pointer should be deflected out beyond
the areas labeled B1 and B2, respectively, at the
bottom of the meter face. Replace the front panel.
IMPORTANT: A zero drift test is best
performed after the Electometer has been left
unused with the Zero Switch in the ZERO LOCK
position for at least four hours. During use with
high voltages, or during battery replacement or
other maintenance, charges may be produced on
the insulators of the input circuit. The bleeding
off of these charges may appear as excessive zero
drift.
ä
5
012-03175E
④ The replacement MOS-FET will probably come in
Calibration
an anti-static bag or may be wrapped in aluminum
foil. The leads will be protected by a thin ring or
spring that is wound around the leads near where
they protrude from the base of the transistor. Gently
remove the MOS-FET from the bag or foil, but do
not remove the thin wire ring that is around the
leads. Leave this wire ring in place until after the
MOS-FET is seated in the socket.
① Remove the four screws that fasten the front panel
to the case, then gently lift the front panel out of the
case.
② Turn the POWER switch to ON.
③ Set the FUNCTION switch to 3.
④ Flip the Zero Switch to ZERO LOCK. With the
¯zero adjust knob midway between its extreme cw
and ccw positions, adjust the Zero Calibration Potentiometer to zero the meter.
⑤ The MOS-FET has a small metal tab protruding
from one side (see Figure 6). The lead directly below the tab (as seen from the top side of the transistor) is lead number 8. Count back to lead number
5, as shown, and gently bend the lead up.
⑤ Set the Function Switch to 30, zero the meter using
the zero adjust knob on the front panel, then connect the INPUT of the Electrometer to a known, accurate 30 VDC source.
⑥ Insert the leads of the MOS-FET, except for lead 5,
into the socket so that the metal tab lines up with
the notch on the side of the socket as shown in the
figure.
⑥ Flip the Zero Switch to the PUSH TO ZERO setting.
⑦ Insert lead number 5 into the socket that is con-
⑦ Adjust the Calibration Potentiometer (see Figure 5)
nected to the adjacent binding post. This may be
done by
inserting the lead through the slot in the end of the
socket, and then bending the end of the lead back
and crimping it tightly. Now gently pull off the thin
ring of wire that is wound around the leads. This
may require thin nose pliers or "tweezers".
until the meter reads 30 volts.
⑧ Press the Zero Switch, then release it. The meter
should still read 30 volts. If it doesn’t, readjust the
Calibration Potentiometer until it does.
MOS-FET Replacement
If the meter can’t be zeroed using the ZERO ADJUST
knob with the Zero Switch set to ZERO LOCK, the
MOS-FET has probably failed. (MOS-FET is an
acronym for Metal Oxide Semiconductor-Field Effect
Transistor). You can order a replacement from
PASCO scientific (Part # 422-001) . When ordering a
replacement part, be sure to include the model number
of the Electrometer.
⑧ Replace the cover.
Repair
Should your Electrometer have problems that are not
covered in the preceding sections, we strongly suggest
you return it to PASCO scientific for repair.
MOS-FET
To replace the MOS-FET:
2
① Turn the Electrometer off.
② Remove the four corner screws that fasten the front
1
3
8
4
7
5
6
panel to the case, and gently lift out the front panel.
③ Gently pull the MOS-FET out of its socket (see Fig-
Align pin 8, the pin
directly below the
tab, with the notch
in the socket, as
shown.
ure 5). Avoid yanking or twisting it, as this may
damage the transistor socket.
Insert pin 5 into
this socket
Figure 6 MOS-FET Installation
6
012-03175E
SCHEMATIC
Model ES-9054B Electrometer
(Drawing #956-02859)
7
012-03175E
Parts List
Reference
R1,2,5,13,
20,21
R3
R4
R6,24
R7
R8
R9
R10,11,19
R12
R14
R15
R16
R17
R18
R22
R23
C1,3
C2,5
C4
C6
C7
Q1
Q2
U1
U2
S1
S2
M1
Description
PASCO Part #
Resistor, 10 ký, 1/4 W, 5%
113-103
Resistor, 1 ký, 1/4 W, 5%
Resistor, 13 ký, 1/4 W, 5%, C.C.
Resistor, 470 ý, 1/4 W, 5%
Potentiometer, 10 ký, 1/4 W, 30%
Resistor, 330 ý, 1/4 W, 5%
Trimpot, 500 ý
Resistor, 3.01 ký, 1/8 W, 1%, MF
Resistor, 470 ký, 1/4 W, 5%
Resistor, 301 ý, 1/8 W, 1%
Resistor, 698 ý, 1/8 W, 1%, MF
Resistor, 2 ký, 1/8 W, 1%, MF
Resistor, 6.98 ký, 6.81 ký, 1/8 W, 1%
Potentiometer, 5 ký, 10%
Resistor, 100 ý, 1/4 W, 5%
Resistor, 100 Mý, 1/2 W, 20%
Capacitor, 1.0 µf, 10%, 35 V, Axial
Capacitor, 0.1 µf, 25 V, Monolithic
Capacitor, 100 pf
Capacitor, 0.001µf, 5%, 600 V
Capacitor, 24 pf, 5%, 600 V
Transitor—2N3906
Transistor—MOS-FET 3N190
IC—TL431 Voltage Regulator
IC—LM324N
Switch—Slide, 2 Pole, 2 Position
Switch—2 Pole, 6 Position, Rotary
Meter
113-102
113-133
113-471
140-006
113-331
142-031
124-007
113-474
124-004
124-005
124-006
124-008
142-018
113-101
150-007
220-004
210-018
210-014
216-013
216-003
420-003
422-001
430-083
430-027
512-007
510-019
525-00682
8
012-03175E
Electrometer
Technical Support
Feedback
Contacting Technical Support
If you have any comments about the product or manual,
please let us know. If you have any suggestions on
alternate experiments or find a problem in the manual,
please tell us. PASCO appreciates any customer
feedback. Your input helps us evaluate and improve our
product.
Before you call the PASCO Technical Support staff, it
would be helpful to prepare the following information:
➤ If your problem is with the PASCO apparatus, note:
­ Title and model number (usually listed on the
label);
To Reach PASCO
­ Approximate age of apparatus;
For technical support, call us at 1-800-772-8700
(toll-free within the U.S.) or (916) 786-3800.
­ A detailed description of the problem/sequence of
fax:
(916) 786-3292
e-mail: techsupp@pasco.com
web:
events (in case you can’t call PASCO right away,
you won’t lose valuable data);
­ If possible, have the apparatus within reach when
calling to facilitate description of individual parts.
www.pasco.com
➤ If your problem relates to the instruction manual,
note:
­ Part number and revision (listed by month and
year on the front cover);
­ Have the manual at hand to discuss your
questions.
012-01568C
12/94
$1.00
Instruction Sheet
for the PASCO
Model ES-9049A
POWER SUPPLY
Introduction
When using the 1000 VDC range use the black and green
binding posts. When the green binding post is used there
is a 100 MΩ resistor in series with the output. This eliminates the hazard of shock if the green terminal is accidentally touched. However, if one attempts to measure the
output of this terminal with a meter having less than several hundred MΩ of input impedance the meter on the
ES-9049A and the measuring meter will not read the
same. This is due to the voltage drop across the 100 MΩ
resistor produced by the current needed to drive the
meter.
Voltage output is varied by the voltage control knob.
Specifications:
➀ Ranges:
a) 1000 VDC, less than 2% ripple peak-to-peak, unregulated (maximum short circuit current less than
0.01 mA)
b) 30 VDC at 20 mA, 0.3% ripple peak-to-peak, line
and load regulation to within 1%.
The PASCO Model ES-9049A Power Supply is a two
range supply providing all the necessary potentials for
PASCO electrostatics equipment.
➁ Meter: Two scale, +/- 3% of full-scale accuracy.
➂ Power:
Operating Instructions
a) 110-130 VDC, 60 Hz
Turn the unit ON by turning the VARIABLE control
knob clockwise.
b) 220/240 VDC, 50 Hz
Select the 30 VDC or 1000 VDC range using the OUTPUT switch. The center position of the switch
(STANDBY) will produce a zero output at the terminals,
regardless of the voltage control settings.
➃ Fuse:
a) 0.2 A, Slo-Blo. (110-130 VDC)
b) 0.1 A, Slo-Blo. (220/240 VDC)
➄ Dimensions: 17.5 x 13.5 x 6 cm
When using the 30 VDC range use the red and black
binding posts. The black binding post is connected to the
third prong (ground) on the power cord.
© 1989 PASCO scientific
This instruction sheet written/edited by: Dave Griffith
Power Supply
012-01568C
Troubleshooting Tips
➀ No output on any range:
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
Fuse blown
➁ Low output on 1000 VDC range:
CAUTION:
TO PREVENT THE RISK OF ELECTRIC SHOCK, DO
NOT REMOVE COVER ON UNIT. NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
Defective capacitor C2, C3, C4, or C5.
➂ No output on 30 VDC range but other range is all right:
Defective zener diode CR5 or power transistor Q1.
➃ Proper output, but no meter readings:
Defective meter M1.
The lightning flash with arrowhead, within
an equilateral triangle, is intended to alert
the user of the presence of uninsulated
“dangerous voltage” within the product’s
enclosure that may be of sufficient magnitude to constitute a risk of electric shock to
persons.
Limited Warranty
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workmanship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return shipment will not be covered by the warranty.) Shipping
costs for returning the equipment, after repair, will be
paid by PASCO scientific.
The exclamation point within an equilateral triangle is intended to alert the
user of the presence of important operating and maintenance (servicing) instructions in the literature accompanying the appliance.
Maintenance
There is no routine maintenance required for the ES9049A Power Supply. However, power line surges can
blow the protective fuse without damaging the instrument. Therefore, should the instrument fail to operate and
the fuse is blown, replace it with a new fuse of the appropriate value. If the instrument subsequently works properly, no further action is necessary. If the fuse blows
again (it may take 15 seconds), refer to the ‘Repairs’ section in this manual.
Equipment Return
Should this product have to be returned to PASCO scientific, for whatever reason, notify PASCO scientific by
letter or phone BEFORE returning the product. Upon
notification, the return authorization and shipping instructions will be promptly issued.
➤NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT AN
AUTHORIZATION.
Repairs
Should the ES-9049A Power Supply require repair, it is
strongly recommended that the unit be returned to
PASCO scientific. Because PASCO is thoroughly familiar with the instrument and maintains a complete stock of
replacement parts, repairs can be made quickly and at low
cost.
When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing.
If field repair is desired, a schematic and parts list are included in the following section. A brief list of malfunctions and their probable causes are also given.
2
Power Supply
012-01568C
PARTS LIST
Specification
Resistors:
22K, 1/4W, 5%
18K, 2W, 5%
1K, 2W, 5%
4.7M, 1/4W, 5%
150K, 1/2W, 1%
100M, 1/2W, 5%
4.99M, 1/2W, 1%
POT, Two Section
Capacitors:
10mF, 450V, Electrolytic
.47mF, 400V, Mylar
Transformer:
Power, 115/230-2X115V
Diodes/Semiconductors:
1N4007, 1000PIV, 1A Silicon Rect
1N4753A, 36V, 1W, 5% Zener
LED Red
Power Transistor RCA40412 NPN
Switch:
Slide, 4Pole, 3Position
Fuse/Meter:
.2A SLO-BLO (110-130VDC)
.1A SLO-BLO (220/240VDC)
Meter
Mechanical:
Bakelite Case, Black
Front Panel
Control Knob
Binding Post, Red
Binding Post, Black
Binding Post, Green
Fuse Holder
Power Cord, Domestic
Power Cord, European
Dissipater
Pasco part no.
Reference
113-223
110-183
110-102
113-475
122-064
150-006
150-015
140-032
R1
R2
R3
R4, R5
R6
R7
R8
R9A/B*, S2*
222-003
214-007
C1
C2-C5
322-009
T1
410-002
412-004
527-001
420-005
CR1-CR4
CR5
CR6
Q1
512-016
S1
530-001
530-006
525-00804
F1
F1
M1
650-01462
648-00803
620-002
517-013
517-014
517-015
520-003
516-001
516-003
624-001
➤NOTE: R9A/B and S2 are concentrically mounted on the Variable Control shaft and comprise a single unit.
3
Power Supply
012-01568C
SCHEMATIC
4
Includes
Teacher's Notes
and
Typical
Experiment
Results
Instruction Manual and
Experiment Guide for
the PASCO scientific
Model EM-8622
012-04367E
4/94
BASIC ELECTRICITY
L
DE
MO -8622
EM
C
B
CW
A
D
E
-
+
+
C
© 1990 PASCO scientific
$10.00
better
10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA
Phone (916) 786-3800 • FAX (916) 786-8905 • TWX 910-383-2040
ways to
teach physics
012-04367E
Basic Electricity
Table of Contents
Section ...........................................................................................................Page
Copyright, Warranty, and Equipment Return ................................................. ii
Introduction ..................................................................................................... 1
Equipment ........................................................................................................ 1
Getting Started, The Experiments ................................................................... 2
Comments on Meters ....................................................................................... 3
Notes on the Circuits Experiment Board ......................................................... 4
Experiments
Experiment 1: Circuits Experiment Board ....................................... 5
Experiment 2: Lights in Circuits ...................................................... 7
Experiment 3: Ohm's Law ................................................................ 9
Experiment 4: Resistances in Circuits ............................................ 11
Experiment 5: Voltages in Circuits ................................................ 15
Experiment 6: Currents in Circuits ................................................. 19
Experiment 7: Kirchhoff's Rules .................................................... 21
Experiment 8: Capacitors in Circuits.............................................. 23
Experiment 9: Diodes ..................................................................... 25
Experiment 10: Transistors ............................................................... 27
Appendix: Tips and Troubleshooting ........................................................... 29
Replacement Parts List .................................................................................. 31
Teacher's Guide ............................................................................................. 33
Technical Support ................................................................................ Back Cover
i
Basic Electricity
012-04367E
Copyright, Warranty and Equipment Return
Please—Feel free to duplicate this manual
subject to the copyright restrictions below.
Copyright Notice
Equipment Return
The PASCO scientific Model EM-8622 Basic Electricity
manual is copyrighted and all rights reserved. However,
permission is granted to non-profit educational institutions for reproduction of any part of this manual providing the reproductions are used only for their laboratories
and are not sold for profit. Reproduction under any other
circumstances, without the written consent of PASCO
scientific, is prohibited.
Should this product have to be returned to PASCO
scientific, for whatever reason, notify PASCO scientific
by letter or phone BEFORE returning the product. Upon
notification, the return authorization and shipping instructions will be promptly issued.
➤ NOTE: NO EQUIPMENT WILL BE ACCEPTED FOR RETURN WITHOUT AN AUTHORIZATION.
Limited Warranty
When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing. To be certain
the unit will not be damaged in shipment, observe the
following rules:
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workmanship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return shipment will not be covered by the warranty.) Shipping
costs for returning the equipment, after repair, will be
paid by PASCO scientific.
➀ The carton must be strong enough for the item
shipped.
➁ Make certain there is at least two inches of packing
material between any point on the apparatus and the
inside walls of the carton.
➂ Make certain that the packing material can not shift in
the box, or become compressed, thus letting the instrument come in contact with the edge of the box.
Address:
PASCO scientific
10101 Foothills Blvd.
P.O. Box 619011
Roseville, CA 95678-9011
Credits
This manual authored by: Clarence Bakken
This manual edited by: Dave Griffith
Teacher’s guide written by: Eric Ayars
ii
Phone:
(916) 786-3800
FAX:
(916) 786-8905
012-04367E
Basic Electricity
Introduction
The PASCO Circuits Experiment Board is designed to
implement a large variety of basic electrical circuits for
experimentation. The Circuits Experiment Board can be
used for experiments beginning with a simple complete
circuit and continuing on to a study of Kirchhoff’s Laws
and characteristics of diodes and transistors. A labeled
pictorial diagram of the Experiment Board appears in
Figure 1.2 of Experiment 1.
Equipment
The PASCO Model EM-8622 Circuits Experiment Kit
includes the following materials:
012-04367A
3/91
Instruction Manual and
Experiment Guide for
the PASCO scientific
Model EM-8622
(2) Circuits Experiment Boards,
(1) Resistor–– 3.3 Ω, 2W, 5%
BASIC ELECTRICITY
(1) Potentiometer–– 25 Ω, 2W
(1) Transistor Socket
(32) Springs
(1) Battery Holder
(3) Light Sockets
Copyright © November 1990
(3) #14 Light Bulbs – 2.5 V, 0.3 A*
L
DE
MO -8622
M
E
(1) Storage Tube
$10.00
better
10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA
Phone (916) 786-3800 • FAX (916) 786-8905 • TWX 910-383-2040
ways to
teach physics
(1) Component Bag
Resistors
C
(2) 10 Ω–– 1 watt
B
(3) 100 Ω–– 1/2 watt
A
CW
(8) 330 Ω–– 1/2 watt
-
(3) 560 Ω–– 1/2 watt
D
(3) 1000 Ω–– 1/2 watt
E
-
+
+
C
(2) 100 K Ω–– 1/2 watt
(2) 220 K Ω–– 1/2 watt
(2) Diodes 1N-4007
(2) Transistors 2N-3904
Capacitors
(2) 100 µ F–– 16 volts
(2) 330 µ F–– 16 volts
Wire Leads–– 22 ga.
(1) Experiment Manual
* NOTE: Due to manufacturer's tolerances,
wattage may vary by 15-30% from bulb to bulb.
1
Basic Electricity
012-04367E
Getting Started
➀ Open the zip-lock bag containing the resistors and
Store the remainder of the components in the ziplock bag until needed in future experiments.
other components. Distribute the following resistors
and wires to each of the boards, storing them in the
plastic holder at the top of the board:
➁ Students will need to use the same resistors, same batteries, etc. from one experiment to another, particularly during experiments 4 to 6. Labeling of the
boards and your meters will enable students to more
easily have continuity in their work. A pad has been
included on the board for purposes of labeling individual boards. Use of a removable label or using a
permanent marker are two alternatives.
(3) 5" Wire Leads (12.7 cm)
(4) 10" Wire Leads (25.4 cm)
(1) 100 Ω Resistor (brown, black, brown, gold)
(3) 330 Ω Resistors (orange, orange, brown, gold)
(1) 560 Ω Resistor (green, blue, brown, gold)
(1) 1000 Ω Resistor (brown, black, red, gold)
The Experiments
Additional Equipment needed:
The experiments written up in this manual are developmental, starting from an introduction to the Circuits
Experiment Board and complete circuits, through series
and parallel circuits, ultimately resulting in diode and
transistor characteristics. These experiments can be used
in combination with existing labs that the teacher employs, or may be used as a complete lab unit.
Experiment 1
Circuits Experiment Board
Experiment 2
Lights in Circuits
Experiment 3
Ohm’s Law
Experiment 4
Resistances in Circuits
Experiment 5
Voltages in Circuits
Experiment 6
Currents in Circuits
Experiment 7
Kirchhoff’s Rules
Experiment 8
Capacitors in Circuits
Experiment 9
Diode Characteristics
Experiments 3-10 Digital Multimeter, VOM or
VTVM (See discussion on page 3)
Experiments 8-10 The Meter needs at least 106 Ω
input impedance
Experiment 10 Transistor Characteristics
2
Experiment 8
A timing device is needed,
0.1 second resolution.
Experiment 9
A.C. Power Supply and an
Oscilloscope (optional)
012-04367E
Basic Electricity
Comments on Meters
VOM:
VTVM:
The Volt-Ohm-Meter or VOM is a multiple scale, multiple
function meter (such as the PASCO SB-9623 Analog
Multimeter), typically measuring voltage and resistance,
and often current, too. These usually have a meter movement, and may select different functions and scales by
means of a rotating switch on the front of the unit.
The Vacuum Tube Voltmeter or VTVM is a multiple
scale, multiple function meter, typically measuring
voltage and resistance. They do not usually measure
current. The meter is an analog one, with a variety of
scales, selected with a rotating switch on the front of the
meter.
Advantages: VOM’s may exist in your laboratory and
thus be readily accessible. A single meter may be used to
make a variety of measurements rather than needing
several meters.
Advantages: VTVM’s have high input resistances, on
the order of 106 Ω or greater. By measuring the voltage
across a known resistance, current can be measured with
a VTVM.
Disadvantages: VOM’s may be difficult for beginning
students to learn to read, having multiple scales corresponding to different settings. VOM’s are powered by
batteries for their resistance function, and thus must be
checked to insure the batteries are working well. Typically, VOM’s may have input resistances of 30,000 Ω on
the lowest voltage range, the range that is most often used
in these experiments. For resistances in excess of
1,000 Ω, this low meter resistance affects circuit operation during the taking of readings, and thus is not usable
for the capacitor, diode and transistor labs.
Disadvantages: VTVM’s have multiple scales. Students
need practice to avoid the mistake of reading the incorrect
one. An internal battery provides the current for measuring resistance, and needs to be replaced from time to time.
Grounding problems can occur when using more than one
VTVM to make multiple measurements in the same
circuit.
Panelmeters:
Individual meters, frequently obtained from scientific
supply houses, are available in the form of voltmeters,
ammeters, and galvanometers (such as PASCO’s
SE-9748 Voltmeter 5 V, 15 V , SE-9746 Ammeter 1 A,
5 A and SE-9749 Galvanometer ± 35 mV). In some
models, multiple scales are also available.
DMM:
The Digital Multimeter or DMM is a multiple scale,
multiple function meter (such as the PASCO SB-9624
Basic Digital Multimeter or the SE-9589 General Purpose
DMM), typically measuring voltage and resistance, and
often current, too. These have a digital readout, often
with an LCD (Liquid Crystal Display). Different functions and scales are selected with either a rotating switch
or with a series of push-button switches.
Advantages: Meters can be used which have the specific
range required in a specific experiment. This helps to
overcome student errors in reading.
Disadvantages: Using individual meters leads to errors
in choosing the correct one. With limited ranges, students
may find themselves needing to use another range and not
have a meter of that range available. Many of the
individual meters have low input impedances
(voltmeters) and large internal resistances (ammeters).
Ohmmeters are almost nonexistent in individual form.
Advantages: DMM’s are easily read, and with their
typically high input impedances (>106 Ω) give good results
for circuits having high resistance. Students learn to read
DMM’s quickly and make fewer errors reading values.
Reasonable quality DMM’s can be purchased for $60 or
less. PASCO strongly recommends the use of DMM’s.
Light Bulbs
Disadvantages: DMM’s also require the use of a battery,
although the lifetime of an alkaline battery in a DMM is
quite long. The battery is used on all scales and functions. Most DMM’s give the maximum reading on the
selector (i.e., under voltage, “2” means 2-volt maximum,
actually 1.99 volt maximum). This may be confusing to
some students.
The #14 bulbs are nominally rated at 2.5 V and 0.3 A.
However, due to relatively large variations allowed by
the manufacturer, the wattage of the bulbs may vary by
15 to 30%. Therefore, supposedly “identical” bulbs may
not shine with equal brightness in simple circuits.
3
Basic Electricity
012-04367E
Notes on the Circuits Experiment Board
The springs are securely soldered to the board and serve
as a convenient method for connecting wires, resistors
and other components. Some of the springs are connected electrically to devices like the potentiometer and
the D-cells. In the large Experimental Area, the springs
are connected in pairs, oriented perpendicular to each
other. This facilitates the connection of various types of
circuits.
When connecting a circuit to a D-cell, note the polarity
(+ or -) which is printed on the board. In some cases the
polarity is not important, but in some it will be imperative. Polarity is very important for most meters.
Connections are made on the Circuits Experiment Board
by pushing a stripped wire or a lead to a component into a
spring. For maximum effect, the stripped part of the wire
should extend so that it passes completely across the
spring, making contact with the spring at four points.
This produces the most secure electrical and mechanical
connection.
If a spring is too loose, press the coils together firmly to
tighten it up. The coils of the spring should not be too
tight, as this will lead to bending and/or breaking of the
component leads when they are inserted or removed. If a
spring gets pushed over, light pressure will get it straightened back up.
Spring
The components, primarily resistors, and small wires can
be stored in the plastic container at the top of the board.
Encourage students to keep careful track of the components and return them to the container each day following
the lab period.
Wire
(top view)
(side view)
Figure 1 Diagram of wires and springs
4
012-04367E
Basic Electricity
Experiment 1: Circuits Experiment Board
EQUIPMENT NEEDED:
-Circuits Experiment
-D-cell Battery
-Graph
-Board
-Wire Leads
-Paper
Purpose
The purpose of this lab is to become familiar with the Circuits Experiment Board, to learn how to
construct a complete electrical circuit, and to learn how to represent electrical circuits with circuit
diagrams.
Background
➀ Many of the key elements of electrical circuits have been reduced to symbol form. Each symbol
represents an element of the device’s operation, and may have some historical significance. In this
lab and the ones which follow, we will use symbols frequently, and it is necessary you learn
several of those symbols.
Wire
Switch
Battery
(Cell)
Light
Resistor
Fuse
➁ The Circuits Experiment Board has been designed to conduct a wide variety of experiments easily
and quickly. A labeled pictorial diagram of the Experiment Board appears on page 6. Refer to
that page whenever you fail to understand a direction which mentions a device on the board itself.
➂ Notes on the Circuits Experiment Board:
a) The springs are soldered to the board to serve as convenient places for connecting wires,
resistors and other components. Some of the springs are connected electrically to devices like
the potentiometer and the D-cells.
b) If a spring is too loose, press the coils together firmly to enable it to hold a wire more tightly.
If a spring gets pushed over, light pressure will get it straightened back up. If you find a spring
which doesn’t work well for you, please notify your instructor.
c) The components, primarily resistors, are contained in a plastic case at the top of the board.
Keep careful track of the components and return them to the storage case following each lab
period. This way you will get components with consistent values from lab to lab.
d) When you connect a circuit to a D-cell (each “battery” is just a cell, with two or more cells
comprising a battery) note the polarity (+ or -) which is printed on the board. Although in
some cases the polarity may not be important, in others it may very important.
e) Due to normal differences between light bulbs, the brightness of “identical” bulbs may vary
substantially.
5
Basic Electricity
012-04367E
Procedure
➀ Use two pieces of wire to make connections between the springs on one of the light bulbs to
the springs on the D-cell in such a way that the light will glow. Discuss with your lab partner
before you begin actually wiring your circuit which connections you intend to make, and why
you think you will be successful in activating the light. If you are not successful, try in order:
changing the wiring, using another light, using another cell, asking the instructor for assistance.
a) Sketch the connections that the wires make when you are successful, using the symbols
from the first page of this lab.
b) Re-sketch the total circuit that you have constructed, making the wires run horizontally
and vertically on the page. This is more standard in terms of drawing electrical circuits.
➁ Reverse the two wires at the light. Does this have any effect on the operation? Reverse the
two wires at the cell. Does this have any effect on the operation?
connection such as one of the three around the
transistor socket as shown on the right as a
“switch.” Connect one lead from the battery to
this spring and then take a third wire from the
spring to the light. You can now switch the
power “on” and “off” by connecting or not
connecting the third wire.
➤
➤
➂ In the following steps, use a vacant spring
Can be
removed
“Switch”
Figure 1.1
➃ Use additional wires as needed to connect a second light into the circuit in such a way that it is
also lighted. (Use a “switch” to turn the power on and off once the complete wiring has been
achieved.) Discuss your plans with your lab partner before you begin. Once you have
achieved success, sketch the connections that you made in the form of a circuit diagram.
Annotate your circuit diagram by making appropriate notes to the side indicating what
happened with that particular circuit. If you experience lack of success, keep trying.
➤ NOTE: Is your original light the same brightness, or was it brighter or dimmer that it was
during step 1? Can you explain any differences in the brightness, or the fact that it is the
same? If not, don’t be too surprised, as this will be the subject of future study.
➄ If you can devise another
1.5 volts
D cell
Model EM-8622
CIRCUIT EXPERIMENT
BOARD
1.5 volts
D cell
Springs
C
KIT NO.
Box
Transistor
B
Return the components and
wires to the plastic case on
the Circuits Experiment
Board. Return the equipment to the location indicated by your instructor.
Storage
Socket
A
➅ Disconnect the wires.
Battery Holder
Circuits Experiment Board
Model 555-04182-1
2 amp slow blow fuse
way of connecting two lights
into the same circuit, try it
out. Sketch the circuit
diagram when finished and
note the relative brightness.
Compare your brightness
with what you achieved with
a single light by itself.
Light Bulbs
Resistor (3.3 Ω)
Figure 1.2
6
Potentiometer
012-04367E
Basic Electricity
Experiment 2: Lights in Circuits
EQUIPMENT NEEDED:
-Circuits Experiment Board
-Wire Leads
-Two D-cell Batteries
-Graph Paper.
Purpose
The purpose of this lab is to determine how light bulbs behave in different circuit arrangements.
Different ways of connecting two batteries will also be investigated.
Procedure
PART A
➤ NOTE: Due to variations from bulb to bulb, the brightness of one bulb may be substantially
different from the brightness of another bulb in “identical” situations.
➀ Use two pieces of wire to connect a single light bulb to one of the D-cells in such a way that the
light will glow. Include a “switch” to turn the light on and off, preventing it from being on
continuously. (You should have completed this step in Experiment 1. If that is the case, review
what you did then. If not, continue with this step.)
➁ Use additional wires as needed to connect a second light into the circuit in such a way that it is
also lighted. Discuss your plans with your lab partner before you begin. Once you have
achieved success, sketch the connections that you made in the form of a circuit diagram using
standard symbols. Annotate your circuit diagram by making appropriate notes to the side
indicating what happened with that particular circuit.
➤ NOTE: Is your original light the same brightness, or was it brighter or dimmer than it was
during step 1? Can you explain any differences in the brightness, or why it is the same?
➂ If one of the light bulbs is unscrewed, does the other bulb go out or does it stay on? Why or
why not?
➃ Design a circuit that will allow you to light all three lights, with each one being equally bright.
Draw the circuit diagram once you have been successful. If you could characterize the circuit
as being a series or parallel circuit, which would it be? What happens if you unscrew one of
the bulbs? Explain.
➄ Design another circuit which will also light all three bulbs, but with the bulbs all being equally
bright, even though they may be brighter or dimmer than in step 4. Try it. When you are
successful, draw the circuit diagram. What happens if you unscrew one of the bulbs?
Explain.
➅ Devise a circuit which will light two bulbs at the same intensity, but the third at a different
intensity. Try it. When successful, draw the circuit diagram. What happens if you unscrew
one of the bulbs? Explain.
➤ NOTE: Are there any generalizations that you can state about different connections to a set
of lights?
7
Basic Electricity
012-04367E
PART B
➆ Connect a single D-cell to a single light as in step 1, using a spring clip “switch” to allow
you to easily turn the current on and off. Note the brightness of the light.
⑧ Now connect the second D-cell into the circuit as shown in Figure 2.1a. What is the effect
on the brightness of the light?
➤
➤
➤
➤
➤
➤
Figure 2.1a
Figure 2.1b
Figure 2.1c
⑨ Connect the second D-cell as in Figure 2.1b. What is the effect on the brightness?
➉ Finally, connect the second D-cell as in figure 2.1c. What is the effect on the brightness?
➤ NOTE: Determine the nature of the connections between the D-cells you made in steps
8-10. Which of these was most useful in making the light brighter? Which was least
useful? Can you determine a reason why each behaved as it did?
PART C
11
Connect the circuit shown in Figure 2.2. What
is the effect of rotating the knob on the device
that is identified as a “Potentiometer?”
Light
Discussion
➀ Answer the questions which appear during the
Potentiometer
experiment procedure. Pay particular attention
to the “NOTED:” questions.
Battery
➁ What are the apparent rules for the operation of
lights in series? In parallel?
➂ What are the apparent rules for the operation of
batteries in series? In parallel?
➃ What is one function of a potentiometer in a
circuit?
Figure 2.2 (Not to scale)
8
012-04367E
Basic Electricity
Experiment 3: Ohm’s Law
EQUIPMENT NEEDED:
-Circuits Experiment Board
-Multimeter
-Graph Paper.
-D-cell Battery
-Wire Leads
Purpose
The purpose of this lab will be to investigate the three variables involved in a mathematical
relationship known as Ohm’s Law.
Procedure
➀ Choose one of the resistors that you have been given. Using the chart on the back, decode the
resistance value and record that value in the first column of Table 3.1.
Red (+)
Black (-)
Red (+)
Black (-)
Figure 3.1b
Figure 3.1a
➁ MEASURING CURRENT: Construct the circuit shown in Figure 3.1a by pressing the leads
of the resistor into two of the springs in the Experimental Section on the Circuits Experiment
Board.
➂ Set the Multimeter to the 200 mA range, noting any special connections needed for measuring
current. Connect the circuit and read the current that is flowing through the resistor. Record this
value in the second column of Table 3.1.
➃ Remove the resistor and choose another. Record its resistance value in Table 3.1 then measure
and record the current as in steps 2 and 3. Continue this process until you have completed all of
the resistors you have been given. As you have more than one resistor with the same value, keep
them in order as you will use them again in the next steps.
➄ MEASURING VOLTAGE: Disconnect the Multimeter and connect a wire from the positive
lead (spring) of the battery directly to the first resistor you used as shown in Figure 3.1b. Change
the Multimeter to the 2 VDC scale and connect the leads as shown also in Figure 3.1b. Measure
the voltage across the resistor and record it in Table 3.1.
➅ Remove the resistor and choose the next one you used. Record its voltage in Table 3.1 as in step
5. Continue this process until you have completed all of the resistors.
9
Basic Electricity
012-04367E
Data Processing
➀ Construct a graph of Current (vertical axis) vs Resistance.
➁ For each of your sets of data, calculate the ratio of Voltage/Resistance. Compare the values
you calculate with the measured values of the current.
Resistance, Ω
Current, amp
Voltage, volt
Voltage/Resistance
Table 3.1
Discussion
➀ From your graph, what is the mathematical relationship between Current and Resistance?
➁ Ohm’s Law states that current is given by the ratio of voltage/resistance. Does your data
concur with this?
➂ What were possible sources of experimental error in this lab? Would you expect each to
make your results larger or to make them smaller?
Reference
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
0
1
2
3
4
5
6
7
8
9
2nd Digit
1st Digit
No. of Zeros
Tolerance
Figure 3.2
10
Fourth Band
None ±20%
Silver ±10%
Gold ±5%
Red
±2%
012-04367E
Basic Electricity
Experiment 4: Resistances in Circuits
EQUIPMENT NEEDED:
-Circuits Experiment Boar
- Multimeter
-Resistors.
Purpose
The purpose of this lab is to begin experimenting with the variables that contribute to the operation of an electrical circuit. This is the first of a three connected labs.
Procedure
➀ Choose the three resistors having the same value. Enter those sets of colors in Table 4.1 below.
We will refer to one as #1, another as #2 and the third as #3.
➁ Determine the coded value of your resistors. Enter the value in the column labeled “Coded
Resistance” in Table 4.1. Enter the Tolerance value as indicated by the color of the fourth band
under “Tolerance.”
➂ Use the Multimeter to measure the resistance of each of your three resistors. Enter these values
in Table 4.1.
➃ Determine the percentage experimental error of each resistance value and enter it in the appropriate column.
Experimental Error = [(|Measured - Coded|) / Coded ] x 100%.
1st
Colors
2nd 3rd
Coded
Measured
4th Resistance Resistance
%
Error
Tolerance
#1
#2
#3
Table 4.1
➄ Now connect the three resistors into the SERIES CIRCUIT, figure 4.1, using the spring clips on
the Circuits Experiment Board to hold the leads of the resistors together without bending them.
Measure the resistances of the combinations as indicated on the diagram by connecting the leads
of the Multimeter between the points at the ends of the arrows.
11
Basic Electricity
012-04367E
Series
R1
R2
R3
R12=
R23=
➤
R12
➤
➤
➤
R23
R123=
➤
➤
R123
Figure 4.1
➅ Construct a PARALLEL CIRCUIT, first using combinations of two of the resistors, and then
using all three. Measure and record your values for these circuits.
Parallel
R1
➤ NOTE: Include also R13
➆ Connect the COMBINATION
➤
CIRCUIT below and measure
the various combinations of
resistance. Do these follow
the rules as you discovered
them before?
R12 =
➤
R12
R23 =
R2
R123 =
R3
Combination
Figure 4.2
R2
R1
R1 =
R3
R23 =
➤
➤
R1
R123
R2 3
➤
➤
R123 =
➤
Figure 4.3
⑧ Choose three resistors having different values. Repeat steps 1 through 7 as above, recording
your data in the spaces on the next page. Note we have called these resistors A, B and C.
12
012-04367E
Basic Electricity
1st
Colors
2nd 3rd
Coded
Measured
4th Resistance Resistance
%
Error
A
B
C
Table 4.2
Series
RA
RB
RC
RAB =
RAB
RBC =
➤
RBC
➤
➤
RABC
➤
➤
➤
Figure 4.4
Parallel
RA
RAB
RAB =
➤
➤
RBC =
RB
RABC=
RC
Figure 4.5
➤ NOTE: Include also RAC
13
RABC=
Tolerance
Basic Electricity
012-04367E
Combination
RB
RA
RA =
RC
RBC =
➤
➤
RA
➤
➤
RBC
RABC
RABC=
➤
Figure 4.6
Discussion
➀ How does the % error compare to the coded tolerance for your resistors?
➁ What is the apparent rule for combining equal resistances in series circuits? In parallel
circuits? Cite evidence from your data to support your conclusions.
➂ What is the apparent rule for combining unequal resistances in series circuits? In parallel
circuits? Cite evidence from your data to support your conclusions.
➃ What is the apparent rule for the total resistance when resistors are added up in series? In
parallel? Cite evidence from your data to support your conclusions.
Extension
Using the same resistance values as you used before plus any wires needed to help build the
circuit, design and test the resistance values for another combination of three resistors. As
instructed, build circuits with four and five resistors, testing the basic concepts you discovered in this lab.
Reference
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
0
1
2
3
4
5
6
7
8
9
2nd Digit
1st Digit
No. of Zeros
Tolerance
Figure 4.7
14
Fourth Band
None ±20%
Silver ±10%
Gold ±5%
Red
±2%
012-04367E
Basic Electricity
Experiment 5: Voltages in Circuits
EQUIPMENT NEEDED:
-Circuits Experiment Board
-D-cell Battery
-Wire Leads
-Multimeter
-Resistors
Purpose
The purpose of this lab will be to continue experimenting with the variables that contribute to the
operation of an electrical circuit. You should have completed Experiment 4 before working on
this lab.
Procedure
➀ Connect the three equal resistors that you used in Experiment 4 into the series circuit shown
below, using the springs to hold the leads of the resistors together without bending them. Connect two wires to the D-cell, carefully noting which wire is connected to the negative and which
is connected to the positive.
➁ Now use the voltage function on the Multimeter to measure the voltages across the individual
resistors and then across the combinations of resistors. Be careful to observe the polarity of the
leads (red is +, black is -). Record your readings below.
Series
+
-
V1
+
R3
R2
R1
➤
➤
-
+
+
-
+
-
➤
V12
➤
➤
V23
V123
➤
Figure 5.1
R1 =
V1 =
R2 =
V2 =
R3 =
V3 =
R12 =
V12 =
R23 =
V23 =
R123=
V123=
15
➤
➤
Basic Electricity
012-04367E
➂ Now connect the parallel circuit below, using all three resistors. Measure the voltage across
each of the resistors and the combination, taking care with the polarity as before.
➤NOTE: Keep all three resistors connected throughout the time you are making your
measurements. Write down your values as indicated below.
Parallel
+
-
➤
➤
R1
R1 =
V1 =
R2 =
V2 =
R3 =
V3 =
R123 =
V123 =
V1
R2
R3
Figure 5.2
➃ Now connect the circuit below and measure the voltages. You can use the resistance readings you took in Experiment 4 for this step.
Combination
+
-
R2
R1
R1 =
V1 =
R23 =
V23 =
R123 =
V123 =
R3
➤
➤
V1
V123
V23
➤
➤
➤
➤
Figure 5.3
➄ Use the three unequal resistors that you used in Experiment 4 to construct the circuits shown
below. Make the same voltage measurements that you were asked to make before in steps 1
to 4. Use the same resistors for A, B and C that you used in Experiment 4.
16
012-04367E
Basic Electricity
Series
+
-
VA
+
RA
RC
RB
-
+
-
+
-
+
➤
➤
VAB
➤
VBC
VABC
➤
➤
➤
Figure 5.4
RA =
VA =
RB =
VB =
RC =
VC =
RAB =
VAB =
RBC =
VBC =
RABC=
VABC=
Parallel
+
-
➤
➤
RA
VA
RB
RA =
VA =
RB =
VB =
RC =
VC =
RABC=
VABC=
RC
Figure 5.5
17
Basic Electricity
012-04367E
Combination
+
-
RA =
VA =
RBC =
VBC =
RABC=
VABC =
RB
RA
RC
➤
VA
➤
VABC
VBC
➤
➤
➤
➤
Figure 5.6
Discussion
On the basis of the data you recorded on the table with Figure 5.1, what is the pattern for how
voltage gets distributed in a series circuit with equal resistances? According to the data you
recorded with Figure 5.4, what is the pattern for how voltage gets distributed in a series
circuit with unequal resistances? Is there any relationship between the size of the resistance
and the size of the resulting voltage?
Utilizing the data from Figure 5.2, what is the pattern for how voltage distributes itself in a
parallel circuit for equal resistances? Based on the data from Figure 5.5, what is the pattern
for how voltage distributes itself in a parallel circuit for unequal resistances? Is there any
relationship between the size of the resistance and the size of the resulting voltage?
Do the voltages in your combination circuits (see Figures 5.3 and 5.6) follow the same rules
as they did in your circuits which were purely series or parallel? If not, state the rules you see
in operation.
18
012-04367E
Basic Electricity
Experiment 6: Currents in Circuits
EQUIPMENT NEEDED:
-Circuits Experiment Board
-Resistors
-Wire Leads.
-Digital Multimeter
-D-cell Battery
Purpose
The purpose of this lab will be to continue experimenting with the variables that contribute to the
operation of electrical circuits.
Procedure
➀ Connect the same three resistors that you used in Experiments 3 and 4 into the series circuit shown
below, using the springs to hold the leads of the resistors together without bending them. Connect
two wires to the D-cell, and carefully note which lead is negative and which is positive.
Series
+
➁ Now change the leads in your DMM so that
they can be used to measure current. You
should be using the scale which goes to a
maximum of 200 mA. Be careful to observe
the polarity of the leads (red is +, black is -). In
order to measure current, the circuit must be
interrupted, and the current allowed to flow
through the meter. Disconnect the lead wire
from the positive terminal of the battery and
connect it to the red (+) lead of the meter.
Connect the black (-) lead to R1, where the wire
originally was connected. Record your reading
in the table as Io. See Figure 6.2.
R1
-
R2
+
R3
- +
- +
-
Figure 6.1
-
I0
+
+
R1
+
➂ Now move the DMM to the positions indicated
in Figure 6.3, each time interrupting the circuit,
and carefully measuring the current in each
one. Complete the table on the top of the back
page.
R3
R2
- +
-
Figure 6.2
➤ NOTE: You will be carrying values from Experiments 3 and 4 into the table on the back.
19
+
-
Basic Electricity
012-04367E
-
I0
+
+
R1
-
+
- I
2
R3
R2
+
I1
+
-
I3
-
Figure 6.3
R1 =
I0 =
V1 =
R2 =
I1 =
V2 =
R3 =
I2 =
V3 =
R12 =
I3 =
V12 =
R23 =
V23 =
R123=
V123=
➃ Connect the parallel circuit below, using all three resistors. Review the instructions for
connecting the DMM as an ammeter in step 2. Connect it first between the positive terminal
of the battery and the parallel circuit junction to measure I0. Then interrupt the various
branches of the parallel circuit and measure the individual branch currents. Record your
measurements in the table below.
Parallel
+
R1
=
I0 =
V1 =
-
+
=
I1 =
V2
R3
=
I2 =
V3 =
R123 =
I3 =
I4
R1
R2
-
I0
=
+
I1
-
+
I2
-
+
I3
-
R2
V123 =
R3
I4 =
Discussion
Figure 6.4
On the basis of your first set of data, what is the pattern for how
current behaves in a series circuit? At this point you should be able to summarize the
behavior of all three quantities - resistance, voltage and current - in series circuits.
On the basis of your second set of data, are there any patterns to the way that currents behave
in a parallel circuit? At this time you should be able to write the general characteristics of
currents, voltages and resistances in parallel circuits.
20
+
012-04367E
Basic Electricity
Experiment 7: Kirchhoff’s Rules
EQUIPMENT NEEDED:
-Circuits Experiment Board
-Wire Leads
-Resistors.
-Two D-cell Batteries
-Digital Multimeter (DMM)
Purpose
The purpose of this lab will be to experimentally demonstrate Kirchhoff’s Rules for electrical
circuits.
Procedure
➀ Connect the circuit shown in Figure 7.1a using any of the resistors you have except the 10 Ω
one. Use Figure 7.1b as a reference along with 7.1a as you record your data. Record the
resistance values in the table below. With no current flowing (the battery disconnected), measure the total resistance of the circuit between points A and B.
R1
A
R1
C
R2
C
A
B
R2
R4
R3
R5
Wire
R3
D
D
Wire
R4
Figure 7.1a
Figure 7.1b
➁ With the circuit connected to the battery and the current
flowing, measure the voltage across each of the resistors and record the values in the table below.
On the circuit diagram in Figure 7.1b, indicate which side of each of the resistors is positive
relative to the other end by placing a “+” at that end.
➂ Now measure the current through each of the resistors. Interrupt the circuit and place the DMM
in series to obtain your reading. Make sure you record each of the individual currents, as well as
the current flow into or out of the main part of the circuit, IT.
21
B
R5
Basic Electricity
012-04367E
Resistance, Ω
Voltage, volts
Current, mA
R1
V1
I1
R2
V2
I2
R3
V3
I3
R4
V4
I4
R5
V5
I5
RT
VT
IT
Table 7.1
Analysis
➀ Determine the net current flow into or out of each of the four “nodes” in the circuit.
➁ Determine the net voltage drop around at least three (3) of the six or so closed loops. Remember, if the potential goes up, treat the voltage drop as positive (+), while if the potential
goes down, treat it as negative (-).
Discussion
Use your experimental results to analyze the circuit you built in terms of Kirchhoff’s Rules.
Be specific and state the evidence for your conclusions.
Extension
Build the circuit below and apply the same procedure you used previously. Analyze it in
terms of Kirchhoff’s Rules. If possible, try to analyze the circuit ahead of time and compare
your measured values with the theoretically computed values.
R2
R4
R3
R1
V2
R5
V1
Figure 7.2
22
012-04367E
Basic Electricity
Experiment 8: Capacitors in Circuits
EQUIPMENT NEEDED:
– Vacuum Tube Voltmeter (VTVM) or Electrometer (ES-9054B) or Digital Multimeter
(DMM) that has an input impedance of 10 MΩ
or greater.
– Circuits Experiment Board
– Capacitors, Resistors
– Wire Leads
– D-cell Battery
– Stopwatch or timer with 0.1 sec resolution.
Purpose
The purpose of this lab will be to determine how capacitors behave in R-C circuits. The manner in
which capacitors combine will also be studied.
Procedure
➀ Connect the circuit shown in Figure 8.1, using a 100-K Ω resistor and a 100-µF capacitor. Use one
of the spring clips from the transistor socket as a “switch” as shown. Connect the VTVM so the
black “ground” lead is on the side of the capacitor that connects to the negative terminal of the
battery and set it so that it reads to a maximum of 1.5 V DC.
➁ Start with no voltage on the capacitor and
the wire from the “switch” to the circuit
disconnected. If there is a remaining
voltage on the capacitor, use a piece of
wire to “short” the two leads together,
draining any remaining charge. (Touch
the ends of the wire to points B and C as
shown in Figure 1 to discharge the
capacitor.)
“Switch”
➤
A
Resistor
B
Capacitor
C
➂ Now close the “switch” by touching the
wire to the spring clip. Observe the
voltage readings on the VTVM, the
voltage across the capacitor. How would
you describe the manner in which the
voltage changes?
+
V
-
Figure 8.1
➃ If you now open the “switch” by removing the wire from the spring clip, the capacitor should
remain at its present voltage with a very slow drop over time. This indicates that the charge you
placed on the capacitor has no way to move back to neutralize the excess charges on the two
plates.
➄ Connect a wire between points A and C in the circuit, allowing the charge to drain back through
the resistor. Observe the voltage readings on the VTVM as the charge flows back. How would
you describe the manner in which the voltage falls? (It would be reasonable to sketch a graph
showing the manner in which the voltage rose over time as well as the manner in which it fell over time.)
➅ Repeat steps 3-5 until you have a good feeling for the process of charging and discharging of a
capacitor through a resistance.
➆ Now repeat steps 3-5, this time recording the time taken to move from 0.0 volts to 0.95 volts while
charging, tC, and the time taken to move from 1.5 volts to 0.55 volts while discharging, tD. Record
your times along with the resistance and capacitance values in Table 8.1 at the top of the back page.
23
Basic Electricity
012-04367E
Trial
Resistance
Capacitance
tC
tD
1
2
3
4
5
6
7
8
Table 8.1
⑧ Replace the 100-µF capacitor with a 330-µF capacitor. Repeat step 7, recording the charging and
discharging times in Table 8.1. If a third value is available, include it in the data table, too.
⑨ Return to the original 100-µF capacitor, but put a 220-K Ω resistor in the circuit. Repeat step 7,
recording your data in Table 8.1. If a third resistor is provided, use it in the circuit, recording the
data.
➤ NOTE:
➀ What is the effect on charging and discharging times if the capacitance is increased? What
mathematical relationship exists between your times and the capacitance?
➁ What is the effect on charging and discharging times if the resistance of the circuit is increased?
What mathematical relationship exists between your times and the resistance?
➉ Return to the original 100-K Ω resistor, but use the 100-µF capacitor in series with the 330-µF
capacitor. Repeat step 7, recording your results in Table 8.2.
11
Now repeat step 7, but with the 100-µF and the 330-µF capacitors in parallel.
R = __________ C1 = __________C2 = __________
Type of Circuit
tC
tD
Series
Parallel
Table 8.2
➤ NOTE: What is the effect on the total capacitance if capacitors are combined in series? What if
they are combined in parallel? (Refer to Table 8.2).
24
012-04367E
Basic Electricity
Experiment 9: Diodes
EQUIPMENT NEEDED:
-Circuits Experiment Board
-Wire Leads
-1000-Ω Resistor
-330-Ω Resistor.
-Digital Multimeter (DMM)
-Two D-cell Batteries
-1N4007 Diode
Purpose
The purpose of this lab will be to experimentally determine some of the operating characteristics
of semiconductor diodes.
Procedure
➀ Connect the circuit shown in Figure 9.1a using the 1N4007 diode you’ve been supplied and the
1000-Ω resistor. Use Figure 9.1b as a reference along with Figure 9.1a as you record your data.
Note the direction that the diode is
oriented, with the dark band closer to
point B.
“Switch”
➁ With the “switch” closed and the current
flowing, adjust the potentiometer until
there is a voltage of 0.05 volt between
points B and C (VBC). Measure the
voltage across the diode (VAB). Record
your values in the left-hand side of Table
9.1under “Forward Bias”.
A
Diode
B
C
Resistor
➂ Adjust the potentiometer to attain the
following values for VBC: 0.1, 0.2,
0.3,.....2.0 volts. Record the two voltages for each case.
Figure 9.1a
➃ Remove the 1000-Ω resistor and replace it with a 330-Ω
resistor. Repeat steps 3 & 4, going from a voltage of 0.3,
0.4,.....2.0 volts. Record the two voltages in each case.
A
➄ Reverse the orientation of the diode. Set the diode voltage
(VAB) to the values 0.5, 1.0,....3.0 volts. Measure the
resistor voltage (VBC) in each case. Record these values in
the columns labeled “Reverse Bias”.
1N4007
C
Analysis
R
➀ Determine the current flow (I) in each setting by dividing
Figure 9.1b
the voltage across the resistor (VBC) by the resistance.
Where you switched resistors, be sure to change the divisor.
➁ Construct a graph of Current (vertical axis) vs the Voltage across the diode, with the graph
extending into the 2nd quadrant to encompass the negative voltages on the diode.
25
B
Basic Electricity
012-04367E
Discussion
Discuss the shape of your graph and what it means for the operation of a semiconductor
diode. Did the diode operate the same in steps 3 and 4 as it did in step 5? In steps 3 and 4
the diode was “Forward Biased”, while it was “Reverse Biased” in step 5. Based on your
data, what do you think these terms mean? What use might we have for diodes?
Sample Data Table
Diode Type ____________
Forward Bias
R, Ω
VAB, volts VBC, volts
Reverse Bias
I, mA
R, Ω
VAB, volts VBC, volts
Table 9.1
Extensions
➀ If your instructor has a zener diode, carry out the same investigations that you did above.
What differences are there in basic diodes and zener diodes?
➁ Use an LED (light emitting diode) to carry out the same investigations. What differences
are there between basic diodes and LED’s?
26
I, mA
012-04367E
Basic Electricity
Experiment 10: Transistors
EQUIPMENT NEEDED:
-Circuits Experiment Board
-Wire Leads
-1000-Ω Resistor
-100-Ω Resistor.
-Two D-cell Batteries
-Digital Multimeter (DMM)
-2N3904 Transistor (NPN)
Purpose
The purpose of this lab will be to experimentally determine some of the operating characteristics
of a transistor.
Procedure
➀ Connect the circuit shown in Figure 10.1a using the 2N3904 Transistor you’ve been supplied.
Resistor R1 = 1000 Ω and resistor R2 = 100 Ω. Use Figure 10.1b as a reference along with Figure
10.1a as you record your data. Note the leads on the transistor as marked next to the socket in the
drawing.
b
Transistor as seen from
above
c
e
2N3904
A
Socket
R2
R1
C
B
c
R1
b
c
e
b
D
2N3904 C
A
B
R2
e
Figure 10.1b
Figure 10.1a
➁ Adjust the potentiometer carefully until the reading between points A and B is approximately
0.002 volt (2.0 mv). Now read the voltage between points C and D. Record these readings in
your data table. Note that VAB divided by R1 gives the current flowing to the base of the transistor, while VCD divided by R2 gives the current flowing in the collector part of the circuit.
➂ Adjust the potentiometer to give VAB the following readings, each time reading and recording the
corresponding VCD: 0.006, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050, 0.055,
0.060, 0.080, 0.100, 0.150, 0.200, 0.250 volts. Also set VAB to 0.000 volts.
27
D
Basic Electricity
012-04367E
Analysis
➀ For each of your sets of readings, calculate:
IB = VAB / R1 and IC = VCD / R2
Record all of your current readings in mA.
➁ Plot a graph of IC (vertical axis) vs IB. If you find an area or areas where you need more
points to fill out any curves or sudden changes, simply return to step 2 and make the appropriate measurements.
➂ What is the general shape of the graph? Is there a straight-line region? Does it go through
the origin? Why or why not? Relate the behavior of the transistor at the beginning of the
graph to the behavior of the diode in Experiment 9.
➃ What does the leveling off of the graph indicate? Electronics people refer to the transistor as
being “saturated”. How would you describe saturation based on your experiment?
➄ Find the slope of the straight-line region of the graph. This ratio - I C / I B is referred to as
the current amplification of the transistor. It describes how many times greater changes in
the collector current are than the changes in the base current. Report the current amplification of your transistor.
Discussion
Discuss the graph and the calculations you did in the Analysis section.
Sample Data Table
Transistor Type ____________
R1, Ω
VAB, volts
IB, mA
R2, Ω
VCD, volts
IC, mA
Table 10.1
Extensions
➀ What effect would changing the resistance in the collector circuit (R2) make? Try changing
the value to 330 Ω or 560 Ω. Does the graph have the same shape? Is the current amplification the same as before? How does the amplification depend on R2?
➁ Obtain a different transistor and repeat the measurements you made in steps 2 & 3. If it is a
PNP transistor, you will need to reverse the wires coming from the D-cells as the emitter
needs to be positive, not negative, and the collector will be negative.
28
012-04367E
Basic Electricity
Appendix: Tips and Troubleshooting
Correct Circuit, Doesn’t Work
The labs asking for relative brightness ask students to
judge relative brightness only, not an absolute brightness.
This part of the experiment would be aided by having the
room mostly darkened. Additional bulbs can be purchased from PASCO, at Radio Shack, an electronics
store, at auto supplies stores, or possibly a local discount
store.
• Check to see if the circuit is indeed connected correctly and completely.
• Check to see if the battery is giving full voltage.
• Check to see if each wire is making contact with the
spring. If magnet wire is used, the enamel coating
on the outside will prevent electrical connection and
needs to be removed. In some cases, students may
try to make a complete circuit through the insulation.
Batteries
The Circuits Experiment Board is designed to use one or
two D-cells. The voltage delivered by a D-cell is 1.5
volts ±. In practice, alkaline cells give the longest life,
but the less expensive zinc-carbon cells will give adequate results. A single set of batteries was used successfully by ten different classes to complete labs 1,3,4,5, 6
and 7 before being replaced.
Surprising Results
In some cases, there will be no difference in the measurements from one point in the circuit to another. This
doesn’t mean the measurement is trivial or unimportant,
rather it is what we hope the student will learn from his/
her lab work. Not all measurements have to be different.
Resistors
The resistors supplied are listed under Materials on page
1 of this manual. The values have been chosen for clear
results and for helping to extend the life of the D-cells. If
resistors are lost or broken, replacements can be purchased from PASCO, or at any electronics store, including Radio Shack. Other values can be substituted, but for
Experiments 3 through 7, the values should be between
100 Ω and 1500 Ω for best results.
Making a “switch”
➤NOTE: Using the 330 Ω, 560 Ω and 1000 Ω
resistors gives approximate ratios of 1:2:3 for
working towards semi-quantitative understanding
of d.c. circuits.
➤
➤
In the several labs, students are asked to use a “vacant”
spring connection such as one of the three around the
transistor socket as shown on the right as a “switch.” By
connecting one lead from the battery there and then
taking a third wire to the circuit, you can effectively
switch the power “on” and “off” by simply connecting or
not connecting the third wire. This duplicates the action
in a real switch.
The diagram below shows the resistor color code. For
example, a resistor having the colors Orange-OrangeBrown-Silver has the value 330 Ω ± 10%.
Can be
removed
“Switch”
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Gray
White
Figure 2
Lights and Relative Brightness
The lights for this experiment board, #14 bulbs, are
designed for 2.5 volts and 0.3 amperes. A single D-cell
will not light a bulb to maximum brightness, but two cells
in series will give a very bright light.
0
1
2
3
4
5
6
7
8
9
2nd Digit
1st Digit
No. of Zeros
Tolerance
Figure 3
29
Fourth Band
None ±20%
Silver ±10%
Gold ±5%
Red
±2%
Basic Electricity
012-04367E
Wires
Pulling the wire away from the stripper (Figure 3c) causes
the cut end of the insulation to slip off of the wire, leaving
3/8" of exposed wire.
The Circuits Experiment Board can be used with a large
variety of wire types and sizes. We recommend 20 or 22
gauge solid wire with colorful insulation. This will help
students to follow their work more easily and minimize
difficulties in making the transition from paper circuit to
actual circuit on the Circuits Experiment Board.
Pull wire
➤
Stripping Your Own Wire
The wire included with the Basic Electricity Lab is 22
gauge insulated, solid wire in 5" and 10" lengths. The
lengths are stripped at each end.
Figure 3c
If you do not have access to a wire stripper, the wire may
also be stripped by carefully using a knife. Place the wire
on a solid surface. Set the knife blade on the insulation
about 3/8" from the end. With the blade at an angle so it
cannot cut downward into the wire, use the knife to shave
off the insulation.
If you choose to strip your own additional wires, a
commercially available wire stripper can be used to
remove the insulation from each end. The jaws of the
wire stripper are placed on the wire 3/8" from the end.
By squeezing the handles together, the jaws will close on
the wire and cut only as deep as the insulation.
3/8"
➤
➤
➤
Figure 4
After one part of the insulation is removed, turn the wire
and continue shaving off the rest of the insulation.
Squeeze
handles
➤
➤
Figure 3a
Figure 3b
30
012-04367E
Basic Electricity
Replacement Parts List
Item
PASCO Part #
P.C.B. ASSY, BASIC ELECT
004-04340
MANUAL EM-8622
012-04367
RES, 10 OHM, 1W, 5%
111-100
RES, 100 OHM, 1/2W, 5%
112-101
RES, 1K, 1/2W, 5%
112-102
RES, 100K, 1/2W, 5%
112-104
RES, 220K, 1/2W, 5%
112-224
RES, 330 OHM, 1/2W, 5%
112-331
RES, 560 OHM, 1/2W, 5%
112-561
CAP, ELECT-100mF, 16V AXIAL
222-039
CAP, ELECT 330MF, 16V AXIAL
222-040
DIODE-1N4007, 1000PIV, 1A
410-002
TRANSISTOR-2N3904 NPN
420-002
➤NOTE: Replacement parts can be purchased
from PASCO or at most electronic stores including
Radio Shack.
31
Basic Electricity
012-04367E
Notes
32
012-04367E
Basic Electricity
Teacher's Guide
Exp 1 - Circuits Experiment Board
➀
With this method, the lights will each be approximately
the same brightness as in part 1.
Serial:
➁ Reversing things at either end had no effect.
➃➄ There are two different ways of putting two
lamps into the circuit: parallel and serial.
Parallel:
Using this circuit, the lights will be dimmer than in part 1.
Exp 2 - Lights in Circuits
➃➄
➤NOTE: It is best to do these experiments with both
batteries, rather than just one. Connect them in series, as
shown in figure 2.1a. This will make the lights brighter
and easier to see when some of the dimmer circuits are
built.
Again, the circuit may be series or parallel.
Series
Procedure
Parallel
These circuits have the same characteristics as the ones in part
2-3
➀
➅ There are two ways of doing this as well.
➁➂
Parallel-in-Series
a
b
Series
c
There are two ways of making the circuit so that both
lights are on with the same intensity.
Series-in-Parallel
a
b
c
(The parallel portion of the first circuit will be very dim.)
What happens if you unscrew one of the bulbs depends on
which bulb you unscrew. In the first circuit, unscrewing (a) will
turn everything off. Unscrewing (b) or (c) will make (a) dimmer
and leave the other one unaffected. In the second circuit,
unscrewing (c) will make (a) and (b) brighter; while unscrewing
(a) or (b) will make (c) brighter and turn the other one off.
➆-➉ Putting the batteries in series (2.1a) will make things
the brightest, because then the voltage to the lights is the
highest. Batteries in parallel (2.1b) will have the same effect
as one battery. Batteries opposed (2.1c) will have no effect
at all unless one of the batteries is nearly dead.
11 The potentiometer, when used this way, adjusts the brightness of the lamp. (For best results, use the batteries in series
for this part of the lab.)
The lights will be dimmer than in part 1. The electric current
must go through one bulb to reach the other, so disconnecting a
bulb will cause both to go out. (This is how those maddening
“if-one-goes-out-they-all-die-so-Merry-Christmas” lights are
wired.)
Parallel
The lights will show the same intensity as in part 1. The electric
current is going through both bulbs at the same time, so
disconnecting one does not affect the other. (This is how the
Christmas lights you wish you had bought are wired.)
33
Basic Electricity
012-04367E
Exp 3- Ohm's Law
Procedure
0.16
➁-➅)Warn the students to be particularly careful when
0.14
setting up the multimeter to measure current. Attaching an ammeter the wrong way can damage the meter.
Current
0.12
Data Processing
Resistance
100
560
330
1000
10
Current
0.02
0.00
0.00
0.00
0.14
Voltage
1.579
1.582
1.582
1.583
1.549
J
V/R % difference
0.02 -1.87%
0.00 -2.73%
0.00 -3.32%
0.00 -9.17%
0.15 -13.31%
0.1
0.08
0.06
0.04
0.02
J
J
0
0
200
J
400
600
Resistance
J
800
1000
Discussion
➂) The greatest source of error is caused by the meter it-
➀ Current is inversely proportional to R
self. Because the ammeter has some internal resistance, the measured current is less than the current
when the meter is not there.
➁ Yes. A curve fit of the graph above gives Current =
1.36 x Resistance-0.98, which is quite close to the theoretical equation.
Exp 4- Resistances in Circuits
Procedure
➀-➃
#1
#2
#3
Colors
brown-black-brown-gold
brown-black-brown-gold
brown-black-brown-gold
coded
100
100
100
measured
98.9
99.6
99.7
➄ Series
R12 =
R23 =
R123 =
➅ Parallel
R12 =
R23 =
R123 =
R13 =
% error
tolerance
-1.10%
±0.05%
-0.40%
±0.05%
-0.30%
±0.05%
⑧ Series
198.3Ω
199.1Ω
298Ω
RAB =
428Ω
RBC =
891Ω
RABC =
989Ω
Parallel
76.1Ω
RAB =
RBC =
207Ω
RABC =
67.0Ω
RAC =
84.1Ω
Combination
RA =
98.9Ω
207Ω
RBC =
306Ω
RABC =
49.7Ω
49.9Ω
33.3Ω
49.8Ω
➆ Combination
R1 =
98.9Ω
R23 =
49.9Ω
R123 =
148.7Ω
34
012-04367E
Basic Electricity
Colors
A brown-black-brown-gold
B orange-orange-brown-gold
C green-blue-brown-gold
coded
100
330
560
measured
98.9
330
561
% error
-1.10%
0.00%
0.18%
tolerance
±0.05%
±0.05%
±0.05%
➁-➃
In series, the resistances are added.
R = R1 + R2 + R3 + ...In parallel, the reciprocals of the
resistances are added. 1/R = 1/R1 + 1/R2 + 1/R3 +...
This is evidenced in all the data sets above.
Discussion
➀ The actual value matches the coded value much more
closely than required by the tolerances.
Exp 5- Voltages in Circuits
Parallel
measurement
Procedure
Equal Resistors:
Series
1
2
3
12
23
123
Parallel
measurement
1
2
3
123
Combination
measurement
1
23
123
Resistance
100
100
100
200
200
300
A
B
C
ABC
Voltage
0.523
0.528
0.527
1.051
1.055
1.578
A
B
C
AB
BC
ABC
Voltage
1.574
1.574
1.574
1.574
Resistance
A
BC
ABC
100.00
207.64
307.64
Voltage
0.509
1.07
1.579
Discussion
Resistance
33.33
33.33
33.33
33.33
Resistance
100
50
150
Voltage
1.6
1.565
1.565
1.565
1.565
Resistance
100
330
560
430
890
990
J
J
1.4
1.2
1
Voltage
J
0.8
J
0.6
J
1.049
0.529
1.578
0.4
0.2
J
0
Different Resistors:
Series
measurement
67.49
67.49
67.49
67.49
Combination
measurement
Voltage
measurement
Resistance
0
Voltage
200
400
600
Resistance
800
1000
In any series circuit, the voltage is distributed according
to the size of the resistors. (Notice that the graph above,
of the data from the second series circuit, shows this
direct relationship.)
In any parallel circuit, the voltage is the same across all
elements.
In the combination circuit, the voltage acts as if the
parallel resistors were actually one resistor, which is then
in series with the first. The rules are the same.
0.157
0.526
0.897
0.685
1.423
1.581
35
Basic Electricity
012-04367E
Exp 6- Currents in Circuits
➤NOTE:
R1 =
R2 =
R3 =
The resistors used were:
Discussion
100Ω
330Ω
560Ω
In any resistance circuit—series, parallel, or both—the
voltage, current, and resistance are related by Ohm’s
Law:
V = IR
These are the same resistors as were used in the
previous lab, and some of the data here originates in
lab 5.
This pattern, and conclusion, should be apparent in
student data.
➤NOTE: The product of the resistances and
currents obtained experimentally will generally be
lower than the measured voltage. This is due to the
non-zero resistance of the ammeter. When the
meter is in the circuit, its own resistance lessens the
current through that circuit. With most meters, this
error should be less than 5% or so.
Procedure
Series:
The current was the same—1.5 mA—no matter where it
was measured in the circuit.
Parallel:
Measurement Resistance
1
100
2
330
3
560
123
67.5
Current
0.0156
0.0047
0.0028
0.0229
Voltage
1.574
1.574
1.574
1.574
Exp 7- Kirchoff's Rules
Procedure
Second circuit:
First circuit:
+ 2
+
1
+
2
1
+
5
b1
3
1
2
3
4
5
T
R (Ω)
100
560
330
100
330
216
+
b2
3
+
+
+
+ 4
5
+
4
V (V)
0.40
1.17
1.05
0.52
0.65
1.57
1
2
3
4
5
b1
b2
I (mA)
3.9
2.0
3.1
5.1
1.9
7.1
36
R (Ω)
100
560
330
330
100
V (V)
0.27
1.50
0.19
1.07
0.32
1.573
1.588
I (mA)
2.6
2.6
0.5
3.2
3.2
2.6
3.2
012-04367E
Basic Electricity
Analysis
Second circuit:
First circuit:
➀ node (2,3,4):
➀ node (1,3):
-0.1 mA
0.1 mA
node (b1,3,5):
0.1 mA
node (1,2,5):
0.0 mA
➁ loop (b1,1,2,3)
0.001 V
node (3,4,5):
-0.1 mA
loop (b2,5,3,4)
0.001 V
node (2,4):
0.0 mA
loop (b1,1,2,4,b2,5) 0.002 V
➁ loop (1,5,3):
0.001 V
loop (1,2,4,3):
0.001 V
loop (5,2,4):
0.000 V
loop (batt,1,2):
0.001 V
loop (batt,3,4):
0.000 V
loop (batt,1,5,4):
0.001 V
loop (batt,3,5,2):
0.000 V
Discussion
Within the experimental uncertainty of the measuring
device used (a DMM) Kirchoff’s Rules are verified. The
net current flowing into or out of any junction is approximately zero, and the sum of the voltages around any loop
is approximately zero.
Exp 8- Capacitors in Circuits
➆ -11
Procedure
➃ The rate at which the capacitor loses its charge de-
140
pends on the impedance of the meter used to measure
the voltage, as well as on the size of the capacitor. For
this reason, most analog meters are not sufficient for
this lab.
120
1
100,000 Ohm
Z
220,000 Ohm
Time (s)
100
➄
Z
80
60
1
1
40
Voltage
Charging
Z
Z
20
Z
1
1
0
0
Voltage
Time
50
100
150
200 250 300
Capacitance (µF)
350
400
➤NOTES:
➀➁ Charging: t = - R C ln(1-V/Vo)
Discharging: t = - R C ln(V/Vo)
In either case, the time is linearly dependent on
both resistance and capacitance.
➂ Parallel: Cp = C1 + C2
Series: 1/Cs = 1/C1 + 1/C2
Discharging
Time
37
450
Basic Electricity
012-04367E
Exp 9- Diodes
Analysis
The diode acts as a one-way valve for electricity. Current
can flow in one direction, but not in the other.
0.007
Extensions
0.006
0.005
4007
J
J
LED
J
O
➀ A zener diode would be similar to the 4007, except
that there would be a breakdown point on the reverse
biasing, beyond which the current would flow. This
makes them useful for power regulation.
Current
J
O
0.004
J
0.003
0.002
0.001
0
J
O
J
O
J
O
-3
J
O
-2
J
O
-1
J
O
O
O
J
O
J
J
O
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
J
JJJO
0
Diode Voltage
➁) The LED opens up at a higher voltage than the 4007
O
O
(and it lights up).
O
O
O
O
O
O
O
OO
O OO
1
2
3
Exp 10- Transistors
Analysis
➁
Discussion
➀ This graph shows the results of applying different values for R2. The amplification remains the same in
each linear region, but the size of that linear region
changes.
2N3904 Transistor
100 Ohm load
16
12
X
X XX
XX X
XX
XX
XX XX XX X
X
X
2N3904 Transistor
various loads
X
10
50
X
X
8
X
Ñ
10 Ohm load
Ç
47 Ohm load
Ö
100 Ohm load
Ñ
Ñ
X
6
X
X
X
X
0
0.05
0.1
Base Current (mA)
0.15
0.2
➂ The linear region does not include the origin, due to
the non-zero voltage that the junctions within the transistor require to turn on. (Similar to the effect in lab 9)
➃ Beyond the “saturation point”, the transistor is acting
like a short circuit. It offers no resistance to the current; so beyond that point, there is no amplification.
The current is limited only by the battery and resistor.
➄ The current amplification of the transistor tested was
249. This value will vary from transistor to transistor;
it’s usually between 150 and 250 for the 2N3904 transistors supplied with the lab.
á
Ñ
Ñ
Ñ
X
2
0
Ñ
40
X
4
Collector Current (mA)
Collector Current (mA)
14
Ñ
560 Ohm load
Ñ
Ñ
Ñ
Ñ
Ñ
Ñ
Ñ
ÑÑ
Ñ
30
Ñ
Ñ
Ñ
Ñ
Ç
Ç
Ç
Ç
Ñ
Ç
Ç
Ç
Ç
Ñ
Ç
Ñ
20
Ñ
Ç
Ç
Ç
Ç
ÇÑ
10
0
ÇÑ
Ç
Ñ
ÖÖ ÖÖ ÖÖ Ö
Ç
ÖÖ ÖÖ ÖÖ
ÇÑ Ö Ö Ö Ö
ÑÖ
ÇÑÖ
Ö
ÇÖ
Ñ
ÇÖ
Ñ
Ö
Ç
Ñ
ÇÖ
Ñ
Ö
ÑÇ
á á á
Ö á áá á á á á á á á
Çáá
ÖáÑ
Çá
Ñá
Ö
Ç
Ö
Ñ
0
0.05
0.1
Ö
Ö
Ö
á
á
Ö
Ö
á
á
0.15
0.2
0.25
Base Current (mA)
á
0.3
Ö
á
0.35
0.4
➁ The gain and/or saturation characteristics of the transistor will vary, although the basic shape of the graph
will remain the same.
38
012-04367E
Basic Electricity
Technical Support
Feed-Back
Contacting Technical Support
If you have any comments about this product or this
manual please let us know. If you have any suggestions
on alternate experiments or find a problem in the manual
please tell us. PASCO appreciates any customer feedback. Your input helps us evaluate and improve our
product.
Before you call the PASCO Technical Support staff it
would be helpful to prepare the following information:
• If your problem is computer/software related, note:
Title and Revision Date of software.
Type of Computer (Make, Model, Speed).
To Reach PASCO
Type of external Cables/Peripherals.
• If your problem is with the PASCO apparatus, note:
For Technical Support call us at 1-800-772-8700 (tollfree within the U.S.) or (916) 786-3800.
Title and Model number (usually listed on the label).
email: techsupp@PASCO.com
Approximate age of apparatus.
Tech support fax: (916) 786-3292
A detailed description of the problem/sequence of
events. (In case you can't call PASCO right away, you
won't lose valuable data.)
Web: http://www.pasco.com
If possible, have the apparatus within reach when calling. This makes descriptions of individual parts much
easier.
• If your problem relates to the instruction manual, note:
Part number and Revision (listed by month and year on
the front cover).
Have the manual at hand to discuss your questions.
39
012-04221C
11/94
$1.00
Instruction Sheet
for the PASCO
Model ES-9053A
-6
.22 X 10 F
8
.50 X 10 Ω
EXT
INPUT
8
1.0 X 10 Ω
8
2.0 X 10 Ω
RESISTOR -CAPACITOR NETWORK
IN
OPEN
Two resistors and three capacitors are wired into a
switching network, which allows selecting three resistance values (50 ΜΩ, 100 MΩ, and 200 MΩ) in series
with two selectable capacitance values (0.47 µF and .94
µF). A third capacitor (0.22 µF) can be selected in series
or parallel with the other two capacitances.
The switches and external connections allow the following combinations:
• Six combinations of resistors and capacitors in series.
• Two combinations of capacitors in series.
• Two combinations of capacitors in parallel.
Three slide switches determine the component selection
and circuit configuration (charging, discharging, or open circuit). The positions of these slide switches on the front panel
diagram indicate the exact component values being used.
IN
-6
.22 X 10 F
8
.50 X 10 Ω
8
1.0 X 10 Ω
EXT
INPUT
OPEN
OUT
COMPONENTS: ±5%
MAX. 50 VOLTS
-6
.47 X 10 F
(A)
-6
.94 X 10 F
The PASCO Model ES-9053A Resistor-Capacitor Network is designed for the study of RC time constants and
for investigating capacitors connected in series and parallel. The RC time constants range from 25 to 200 seconds,
so charging and decay curves can easily be investigated
using an electrometer, such as the PASCO Model
ES-9054B Student Electrometer, and a stopwatch.
GND
8
2.0 X 10 Ω
Introduction
COMPONENTS: ±5%
MAX. 50 VOLTS
-6
.47 X 10 F
GND
-6
.94 X 10 F
OUT
ES-9053A
RESISTOR - CAPACITOR
NETWORK
GND
GND
8
1.0 x 10 ohms
(B)
-6
.47 x 10 farads
Figure 1: Switch Positions & Equivalent Circuit
Figure 1 (A) shows the slide switches in arbitrary positions, while Figure 1 (B) reflects the corresponding
equivalent circuit diagram.
The three position slide switch on the left (S3) has a
very useful OPEN position. It is often convenient to
stop the charging or discharging process when making
a measurement, and the OPEN position permits the
circuit to be disconnected.
© 1990 PASCO scientific
R-C Network
012-04221C
Five binding posts allow a power supply, such as the
PASCO Model ES-9049A Power Supply, and/or the electrometer to be connected at every possible component
connection in the circuit.
Plot time versus capacitor voltage for several values of
R and C. What is the shape of the curve?
Let us define T as the time required for the capacitor
to charge from 10% to 90% of its final value. What is
the relation between R,C, and T? (Hint: Convert R to
ohms, C to farads, and T to seconds.)
➤IMPORTANT: Never place more than 50 Volts
DC across any component in the R-C network.
When using the ES-9040A Power Supply, use the
30 VDC range only.
➁ Repeat the same experiment as in (1), but measure the
voltage across R as a function of time. (This time
opening the switch stops the current flow, hence
steady-state readings cannot be made.)
The experiment using the R-C network will give only
suggested schematics, such as in Figure 1 (B)—and not
specific switch settings.
According to Ohm’s law, potential is proportional to
resistance multiplied by current. Hence, the potential
across the resistor is proportional to the charging current. What relation is there between the charging current and the charge on the capacitor? (Hint: Part (1)
gives the relation between charge and time, whereas
part (2) gives the relation between time and charging
current.)
Experiment:
Capacitors - Charging and Discharging
It takes a definite amount of time to charge or discharge a
capacitor through a resistance. In this experiment we discover the relationships between capacitance, resistance,
and the time required to charge the capacitor.
B. Discharging Capacitors:
➀ Set up the circuit in Figure 3. Charge the capacitor to
an initial potential of 30 VDC. At time t = 0, close the
switch and use the electrometer to measure the voltage
across the capacitor. (Use the switch for steady state
readings as in part A (1).
Equipment Needed:
RC Network, DC Power Supply, and Electrometer.
The experimental circuits can be easily duplicated by
tracing through the schematic on the front of the network
and setting the switches accordingly. The battery in the
experimental schematics is replaced with the DC Power
Supply. Use the electrometer to measure voltages. DO
NOT GROUND THE ELECTROMETER. (We want
relative voltages.)
R
Procedure:
A. Charging Capacitors:
C
➀ Set up the circuit in Figure 2. At time t = 0, the switch
is closed and capacitor voltage is recorded at regular
time intervals. (A simple way to collect data is to open
the switch at regular intervals and record the steady
state reading. Why is this possible?)
Figure 3
Repeat the experiment with several other values of R and
C. Plot time versus capacitor voltage. Does the time constant (T) remain the same for discharging capacitors as it
does for charging capacitors?
➁ Using the same circuit as in B (1), charge the capacitor
to 30 VDC, and close the switch and measure the voltage across the resistor. Determine the relation between discharging current and capacitor potential.
R
C
Figure 2
2
012-04221C
R-C Network
Specifications
Equipment Return
Resistance:
Three selectable series values:
50 MΩ, 100 MΩ, and 200 MΩ;
±5% Tolerance
Capacitance:
Two selectable series values :
0.47 µF and .94 µF;
One series/parallel value:
0.22 µF;
±5% Tolerance
Should this product have to be returned to PASCO scientific, for whatever reason, notify PASCO scientific by
letter or phone BEFORE returning the product. Upon
notification, the return authorization and shipping instructions will be promptly issued.
Connections:
➤NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT
AN AUTHORIZATION.
Five external connections via banana
jacks / binding posts allow electrical
connections to each circuit node.
When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing. To be certain
the unit will not be damaged in shipment, observe the following rules:
Component Selection: Via three slide switches
Repairs
➀ The carton must be strong enough for the item
shipped.
Because of the extreme simplicity of the ES-9053A R-C
Network and the fact that each component can be tested
from the front panel, this section will only give a list of
replaceable parts. Although PASCO scientific will repair
the ES-9053A it is highly suggested that repairs be made
in the field. Any person with a basic understanding of
electronics is capable of making the necessary repairs.
➁ Make certain there is at least two inches of packing
material between any point on the apparatus and the
inside walls of the carton.
➂ Make certain that the packing material can not shift in
the box, or become compressed, thus letting the instrument come in contact with the edge of the box.
Replacement Parts
PART REF.
DESCRIPTION/RATING
C1
C2, C3
R1, R2
S1, S2, S3
Capacitor, Mylar, .22 mF, 100 V, ±5%
Capacitor, Mylar, .47 mF, 100 V, ±5%
Resistor, 100 MΩ, 3/4 W, ±2%
Switch, Slide, 2 Pole, 4 Position
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workmanship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return shipment will not be covered by the warranty.) Shipping
costs for returning the equipment, after repair, will be
paid by PASCO scientific.
C1
R1
S3
Limited Warranty
R2
S1
S2
C2
C3
PCB Parts Layout
➤NOTE: Complete operational instructions of
other PASCO Electrostatic Accessories and directions for demonstrations possible with the complete
PASCO Electrostatic System are available in the
ES-9051 Accessory and Demonstrations Manual.
For a listing of available Electrostatic equipment
please refer to your current PASCO catalog.
3
R-C Network
012-04221C
IN
EXT
INPUT
EXT
OPEN
S3
C1
.22 µF
± 5%
100 V
R1
100 MΩ
GND
S1
R2
100 MΩ
200M 100M
50M
.22 µF
OUT
.94µF .47 µF
GND
C2
.47 µF, ± 5%
100 V
GND
ES-9053A
SCHEMATIC
4
S2
C3
.47 µF, ± 5%
100 V
GND
Instruction Manual
and Experiment Guide
for the PASCO scientific
Model SF-8616 and 8617
012-03800A
11/89
COILS SET
Copyright © November 1989
$15.00
012-03800A
How to Use This Manual
The best way to learn to use the PASCO Basic Coils Set or
the PASCO Complete Coils Set (referred to collectively as
PASCO Coils Set) is to spend some time experimenting with
it. We’ve organized this manual to get you started as
quickly as possible. We strongly recommend that you read
the Introduction and Experiments sections first. These are
followed by 4 experiments for your students to get started
on. The experiments are ready to send to the copy room.
The Appendix contains technical data on the construction
and operation of the coils.
Introduction
between the magnet and coil is needed. The effect of
moving slow versus moving fast can be demonstrated.
The PASCO scientific SF-8616 Basic Coils Set and SF-8617
Complete Coils Set provide necessary parts to experimentally investigate relationships involved with electromagnetism and electromagnetic induction. Coupled with a galvanometer, an accurate A.C. voltmeter, an A.C. ammeter, an
oscilloscope and an A.C. power supply, little else is needed
to carry out studies in this important area.
Finally, changing the number of coils of wire and repeating
the process will complete an initial investigation. These
investigations are generally semi-quantitative, focusing on
relative sizes and directions. Another way to change the
magnetic field is to provide an alternating magnetic field
through the use of a second coil and an alternating current.
See Figure 3.
Additional equipment which is recommended includes small
but strong magnets such as the ones found in the PASCO
SE-8604 Bar Magnet Set, low constant springs, ring stands,
a magnetic compass and iron filings.
One can study basic electromagnetism. The direction of the
windings is shown on the top of each coil, allowing the
relationship between current direction and the direction of
the resulting magnetic field to be studied. See Figure 1.
IN
OUT
Figure 3
•
The Coils Set provides multiple coils and cores to experiment with this principle. These investigations lead to the
basic relationships involved in transformers, and lead to
more advanced studies of self- and mutual-induction.
d.c. power
compass
amperes
With the addition of
two magnets and small
springs, a classic
interaction of induced
current and electromagnetic effects, plus
simple harmonic
motion, can be studied.
See Figure 4.
Figure 1
Using a coil from either
kit, it is easy to demonstrate that a moving coil
of wire near a magnet, or
a moving magnet near a
coil of wire will induce a
voltage, and therefore a
current. Simply move a
magnet into the coil as
shown in Figure 2, and a
galvanometer will show a
current flow.
Galvanometer
Figure 4
Suggested Experimental Approach
Figure 2
Demonstrate the basic principle of using the core and two
coils to make a transformer. Show coils, core(s), supplies,
loads, meters, etc. Have students develop areas of investigation and then proceed to carry them out. "Research teams"
could investigate different factors and then combine their
results for a comprehensive look at transformers.
Moving the magnet back out will yield a current in the
opposite direction. Reversing the magnet will reverse the
relative currents, also. Leaving the magnet at rest inside the
coil will produce no current. Thus, a change in relationship
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012-03800A
Equipment Supplied
Your SF-8616 Basic Coils Set comes with the items shown in Figure 5a:
a. (1) SF-8609 200-turn Coil
b. (2) SF-8610 400-turn Coils
c. (1) SF-8611 800-turn Coil
d. (1) SF-8614 U-shaped Core
e. (1) Manual
Your SF-8617 Complete Coils Set comes with all of the items in the SF-8616 Basic Coils Set along with the following
additional items, as shown in Figure 5b:
f. (1) SF-8612 1600-turn Coil
g. (1) SF-8613 3200-turn Coil
h. (2) SF-8615 E-shaped Core
a
PASCO
Manual
d
b
b
e
c
Figure 5a
Figure 5b
f
g
h
2
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012-03800A
Experiments
Nature of Magnetic Field from an Electromagnet
The coils from your PASCO Coils Set can be used in
conjunction with a d.c. power supply or a battery to produce
constant magnetic fields. Three possible experiments are
shown below.
•
Figure 8b
d.c. power
ALTERNATIVE: Small magnetic compasses can be used to
probe around the coil to show its magnetic field.
compass
amperes
Figure 9 shows a current carrying coil with a magnetic field
inside. The cross-piece from the U-shaped Core is shown
inserted in the coil, although the same experiment can be
performed without the core. The strength of the electromagnet thus produced could be tested in a number of ways,
including the use of the PASCO SF-8606 Digital Gauss/
Tesla Meter. Note that the dramatic increase in magnetic
field strength with the addition of a core can be clearly
demonstrated.
Figure 6
In Figure 6, a d.c. power supply is connected to the coil. A
nearby magnetic compass is used to show the presence of a
magnetic field and its direction. By noting the direction of
the windings on the coil (See Figure 7), students can develop
the rule for current direction and the resulting magnetic field
direction. This experimental setup can be quantified, leading
to a determination of how much current, through how many
turns, is needed to produce a magnetic field equal to the
earth’s field. Specifics of the experimental design are left to
the teacher and student.
1600
d.c. power
Figure 7
amperes
Figure 9
Solenoid
In Figure 8a and 8b, a coil is shown with its magnetic axis
parallel to the table. A piece of cardboard is mounted so that
it can be inserted into the center of the coil and extend
beyond it on all sides. Iron filings are then sprinkled on the
cardboard around the end of the current carrying coil. The
magnetic field pattern can be quickly demonstrated.
If the cross piece from the U-shaped Core is inserted into a
coil, but not centered, it will be pulled into the coil when the
alternating current is turned on. This demonstrates the basic
action of a solenoid. In experiments with the 400-turn coil, a
voltage of 8-10 volts A.C. was successful in demonstrating
this principle. See Figure 10.
ac power
Iron Core
Figure 8a
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Figure 10
3
012-03800A
Electromagnetic Induction
showed a drop-off to an output voltage of less than 20%
from the input voltage when the two 400-turn coils were
used in this manner.
Use a small, relatively strong bar magnet to demonstrate
electromagnetic induction. It is only necessary to move the
magnet up and down in the center of the coil. If the coil is
attached to a galvanometer, the relative size of the induced
current and the direction can be noted. See Figure 11.
ac volts
ac power
Galvanometer
Figure 11
Figure 14
To improve the mutual induction, an iron core can be
introduced. See Figure 15. Using the cross piece from the
U-shaped core, the induced voltage increased to almost 50%
of the primary voltage under the same conditions as above.
A second way of showing the effect is to connect the coil to
an oscilloscope. See Figure 12
Iron Core
Figure 15
Figure 12
Primary
Secondary
Numerous modifications of the cores which are provided can
be investigated. In each case, the ratio of secondary voltage
to primary voltage is noted. The variables in this situation
thus become: Primary Number of Turns, Secondary Number
of Turns, Existence of a Core, Shape of the Core, Primary
Voltage, Primary Current, Secondary Voltage and Secondary
Current. Students can be led on directed studies, or given
the materials to develop their own experiments. Some
possibilities are shown in Figure 16 below.
NOTE: A galvanometer shows the current
produced, which should be proportional to the size
of the induced voltage. Due to mechanical damping, galvanometers do not rise to the maximum
value, but give useful semi-quantitative measurements of the maximum currents. An oscilloscope
shows the size of the induced voltage directly, and
gives a more instantaneous value.
The set-up below gives a method of “automatically” showing the induced voltage. A light spring which gives a nice
simple harmonic motion with the attached magnet is needed.
Note that the method of attaching the magnet is via a
machine nut which is hooked to the spring and held by the
magnetic field of the magnet. See Figure 13.
ac amperes
ac power
Without Cross Bar
ac amperes
Figure 13
ac power
With Cross Bar
TRANSFORMERS
Leading directly to the study of transformers, the setup in
Figure 14 allows students to see how induction can proceed
by passing magnetic field between the two coils. Using air
as the medium between the two coils, PASCO’s experiments
Figure 16
Primary
4
Secondary 1
Secondary 2
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012-03800A
Experiment 1: Transformer Basics I
Introduction
When an alternating current passes through a coil of wire, it produces an alternating magnetic
field. This is precisely the condition needed for the electromagnetic induction to take place in a
second coil of wire. In this lab you will investigate several of the factors influencing the operation
of a transformer.
Equipment Needed - Supplied
1.
2.
3.
The four coils from the PASCO SF-8616 Basic Coils Set
The U-shaped Core from the PASCO SF-8616 Basic Coils Set
Optional: the additional coils from the PASCO SF-8617 Complete Coils Set
Equipment Needed - Not Supplied
1.
2.
3.
Low voltage ac power supply 0-6 VAC, 0-1 amp such as PASCO Model SF-9582
AC voltmeter 0-6 VAC
Banana connecting leads for electrical connections
Procedure
1.
Set up the coils and core as shown in Figure
1. In the diagram, the coil to the left will be
referred to as the primary coil, and the one
to the right will be the secondary coil. Note
that we are putting in an alternating current
to the primary at one voltage level, and
reading the output at the secondary.
ac volts
ac power
Primary
Secondary
Figure 1
2.
With the 400-turn coil as the primary and the 400-turn coil as the secondary, adjust the input
voltage to 6 volts a.c. Measure the output voltage and record your results in Table 1.1.
3.
Repeat step 2 after inserting the straight cross piece from the top of the U-shaped core.
Record your results. (See Figure 2.)
Iron Core
Primary
Secondary
Primary
Secondary
Primary
Secondary
Figure 2
4.
Repeat step 2 after placing the coils on the sides of the open U-shaped core. Record your
results.
5.
Finally, repeat step 2 after placing the cross piece over the U-shaped core. Record your
results.
6.
Using the core configuration which gives the best output voltage compared to input voltage,
try all combinations of primary and secondary coils. Use a constant input voltage of 6.0 volts
a.c. Record your data in Table 1.2.
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012-03800A
Analysis
1.
Which core configuration gives the maximum transfer of electromagnetic effect to the
secondary coil? Develop a theory to explain the differences between configurations.
2.
From your data in table 1.2, for a primary having a constant number of turns, graph the
resulting output voltage versus the number of turns in the secondary. What type of mathematical relationship exists between numbers of turns of wire and the resulting output voltage?
Is the data ideal? Why or why not?
3.
Consider further improvements to your transformer. What additional changes might you
make to increase the transfer from one coil to the other?
Data and Calculations
Table 1.1
Number of Turns
Primary Coil
Secondary Coil
Input V
Output V
Core
Table 1.2
Core Configuration: ______________________________
Number of Turns
Primary Coil
Secondary Coil
Input V
6
Output V
Core
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012-03800A
Experiment 2: Transformer Basics II
Introduction
In this lab you will investigate several of the factors influencing the operation of a transformer. In
Experiment 1, the output factor was voltage as measured when there was nothing connected to the
secondary (infinite resistance). In this lab, you will investigate input and output currents, in
addition to voltages, with normal sized resistances in the secondary circuit.
Equipment Needed - Supplied
1.
2.
3.
The four coils from the PASCO SF-8616 Basic Coils Set
The U-shaped Core from the PASCO SF-8616 Basic Coils Set
Optional: the additional coils from the PASCO SF-8617 Complete Coils Set
Equipment Needed - Not Supplied
1.
2.
3.
4.
Low voltage ac power supply 0-6 VAC, 0-1 amp such as PASCO Model SF-9582
One or two AC ammeters 0-2 A
Three resistors: 10Ω, 2 Watt; 100Ω, 2 Watt; 1000Ω, 2 Watt
Banana connecting leads for electrical connections
Procedure
1.
Set up the coils, core and 1000-Ω load
resistor as shown in Figure 1. In the
diagram, the coil to the left will be referred
to as the primary coil, and the one to the
right will be the secondary coil. Note that
we provide an alternating current at the
primary at one voltage level, and read the
output at the secondary at possibly a
different value.
ac
amperes
ac
amperes
ac power
R
Primary
Secondary
Figure 1
2. With the 400-turn coil as the primary and the 400-turn coil
as the secondary, adjust the input voltage to 6.0 volts a.c.
With a load resistance of 1000 Ω connected to the
secondary, measure the input current, the output voltage
and the output current. Record your results in Table 2.1.
3.
Repeat step 2 after connecting in a 100 Ω load resistance.
4.
Repeat step 2 after connecting in a 10 Ω load resistance.
5.
Finally, repeat steps 2-4 after changing the secondary coil.
Continue changing the coils until you have tested all
combinations of input and output coils.
6.
Replace the secondary coil with a relatively large diameter
wire (18-20 gauge) wound around the core 5-6 times. See
Figure 2. Again set the input voltage to the primary at 6.0
vac. Connect the ammeter to this new secondary, measuring the current when the resistance is only that of the
ammeter. With the ammeter disconnected, measure the
output voltage.
7.
If you have the SF-8617 Complete Coils Set, arrange the
primary and secondary coils as shown in Figure 3. Run
the same set of experiments you did in steps 2-4, collecting the same items of data.
Figure 2
Secondary
Primary
Figure 3
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012-03800A
Note: Other configurations can be investigated once you have the E-shaped core. At
your instructor’s direction, investigate other methods of arranging the primary and
secondary coils.
8.
If there are more than one PASCO Coils Sets in the laboratory, set up a series of transformers
such as the one diagrammed below in Figure 4. Measure input and output voltages, input and
output currents at various places in the chain. Keep careful track of your measurements and
draft your observations based on these measurements.
Input
Output
Primary
Secondary
Primary
Secondary
Figure 4
Analysis
1.
Calculate the quantities asked for in Table 2.2. Note the suggestion at the bottom of the page.
If you were able to carry out the modification in step 7, a separate data table should be
constructed.
2.
What relationship exists between the output current and the input current for different coils
given a constant load resistance? How does varying the load resistance change the output
current/input current relationship for a given combination of coils? Is the effect the same for
all combinations? Elaborate and make an educated hypothesis on why your experiment
behaved the way it did.
3.
The ideal voltage gain is equal to the number of turns in the secondary divided by the number
of turns in the primary. How did the actual voltage gain (Vout / Vin) compare to the ideal?
4.
Ideally, transformers convert alternating current from one voltage to another with very little
power loss (almost 100% efficient). Looking at your power gain (Pout / Pin), how did your
transformers do compared to ideal transformers?
5.
What combination of voltage and current is gained by having few coils of wire in the secondary? (step 6)
6.
Analyze the behavior of the coils in the E-shaped core, and compare this to the U-shaped
core. Is there a distinct advantage of one over the other? Why? Can an advantage gained be
further enhanced by other changes? What might they be? (step 7)
7.
If you began and ended with the same number of turns in your coils (step 8), how did the
input and output voltages compare? How did the input and output power for the total combination compare? Were principles you experimented with previously in evidence during this
part of the lab?
8
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012-03800A
Data and Calculations
Table 2.1
Number of Turns
Trial #
Primary
Secondary
Load R
Input V
Input I
Output V
Table 2.2
Trial #
Input P
Output P
Voltage Gain
Power Gain
NOTE: It is recommended that the data collected above in Table 2.1 be gathered into a
spread sheet program. Calculations of the input and output power, the voltage gain and
power gain for Table 2.2 can quickly and easily be made using the spread sheet. Additionally, the data can be rearranged quickly to make it easy to analyze.
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9
Output I
012-03800A
Notes:
10
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012-03800A
Experiment 3: Springing into Electromagnetic Induction
Introduction
In this lab an interesting arrangement will allow you to investigate some of the subtelties of
electromagnetic induction. The results will be qualitative, contrary to many of the labs you have
done recently!
Equipment Needed - Supplied
1.
The PASCO Model SF-8616 Basic Coils Set
Equipment Needed - Not Supplied
1.
2.
3.
4.
5.
Two small, relatively strong magnets
Two springs with low force constants
Several machine nuts
Two ring stands
Banana connecting leads for electrical connections
Procedure
1.
Set up the two 400-turn coils, the magnets, springs and ring stands as shown in Figure 1. See
Figure 2 to see how the springs “attach” to the magnets.
Spring
Nut
Magnet
Figure 1
Figure 2
2.
Move the magnet in one coil upward and then release it so that it sets up simple harmonic
motion. Note the reaction of the second magnet. Can you arrive at an explanation as to why
this is happening?
3.
PREDICTION 1: What will happen if you reverse the leads in one of the two coils and repeat
step 2? Try it to see if your prediction is accurate.
4.
PREDICTION 2: What will happen if you were to use additional masses on one magnet,
thereby increasing its period of SHM? Try this by adding several machine nuts onto the
bottom of the magnet. Adjust the height of the ring stand as needed.
5.
PREDICTION 3: What will happen if you were to use a
different spring on one magnet?
Try it.
6.
PREDICTION 4: What will happen if you use a different
number of coils on one side? Try it.
7.
PREDICTION 5: What will happen if you insert another
coil into the circuit, as shown in Figure 3? Try it. Does it
make a difference if different coils are used? Try it.
8.
PREDICTION 6: What will happen if you put a core into
the third coil that you used in step 6? Why? Try it.
Figure 3
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012-03800A
Analysis
1.
Why did the magnets behave as they did? How does your observation relate to electromagnetic induction?
2.
What was the effect of changing the polarity of the leads connecting the two coils? Why?
3.
Why did the behavior change as a result of changing the mass of the magnet and/or the spring
which was used?
4.
Try to develop an explanation to cover the observations you made in steps 6-8. You may
wish to begin considering energy!
12
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012-03800A
Experiment 4: Intermediate Transformers
Introduction
In this lab you will continue investigating transformers. You will investigate additional core
configurations and work into d.c. power supplies, one of the key applications of transformer
technology.
Equipment Needed - Supplied
1.
The PASCO SF-8617 Complete Coils Set
Equipment Needed - Not Supplied
1.
2.
3.
4.
5.
6.
7.
8.
Low voltage ac power supply 0-6 VAC, 0-1 amp such as PASCO Model SF-9582
AC voltmeter 0-6 VAC
AC ammeter 0-2 A
Oscilloscope
Two diodes 1 amp, 50 PIV (min) rectifiers such as 2N4007
Resistor 1000Ω, 2 Watt
Capacitor 470µF
Banana connecting leads for electrical connections
Procedure A
1.
Set up the coils and core as shown in Figure 1. In the diagram, the
coil to the left will be referred to as the primary coil, and the center
one will be the secondary coil.
2.
With the 200-turn coil as the primary and the 800-turn coil as the
secondary, adjust the input voltage to 6.0 volts a.c. With a resistance
of 1000 Ω connected to the secondary, measure the input current, the
output voltage and the output current. Record your results in Table
4.1.
3.
Now replace the 800-turn coil with the two 400-turn coils, stacked on
the same arm of the E-shaped core. With the two coils connected as
shown in Figure 2, with a load resistance of 1000 ohms, measure the
input and output currents and voltages. Record your results in Table
4.1.
4.
Reverse the leads to one of the coils and re-measure the currents and
voltages. Record your results. How did the results compare with step
3? What did you change and why did you get the results you did?
5.
Now move the two 400-turn coils to the third arm of the core. How
do the values for current and voltage compare to those seen in the
previous position of the coils? How would these values compare with
a single 800-turn coil? Set up the single 800-turn coil and test your
hypothesis.
6.
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Primary
Measure the individual voltages and currents of the 400-turn coils of
the secondary when they are connected to the 1000-Ω resistance in
the configuration which gave you the biggest output voltage and
current. How do the two values compare with one another? Do they
add or subtract to any specific values? Do the values you obtain in
the experiment support your understanding of basic series circuits?
Change the leads on one coil and re-measure the individual voltages
and the total voltage. Why do you get your end result?
13
Secondary
Figure 1
Primary
Secondary
Figure 2
012-03800A
Procedure B
7.
Set up the 200-turn coil as primary, and the 800-turn coil as the secondary. Put a diode into
the circuit as shown in Figure 4, and leave the 1000-Ω resistor in as a load.
8.
In this step, set the triggering of your
oscilloscope to “LINE”. This stabilizes the
sweep so that it is sychronized with the a.c.
line voltage. Now connect the ground lead
(often a clip lead) from your oscilloscope to
point A in Figure 3, and the probe to point
B. Note the waveform. With the probe at
point C, again note the waveform and also
any differences between that and the one
found at point A. How would you describe
this difference?
9.
Diode
C
B
Load
Resistor
A
Primary
Figure 3
The waveform seen across the load resistance (A to C) is called a half-wave rectified signal.
Half of the full sine wave passes through the diode, with the other half being blocked. This
produces a directional current (d.c.) but one that is constantly changing in magnitude. To be
useful, the voltage level must be made constant. The addition of an electronic “damper”
should accomplish this.
10. Add the 470 µF capacitor as shown in
Figure 4. What is the new waveform across
the load resistor? Is it still varying as much
as it did previously? What is the d.c. level
of the resulting voltage?
Diode
•
C
B
Load
Resistor
Capacitor
11. Now change the 1000-Ω resistor to a 10-Ω
resistor in the same circuit. How does this
affect the waveform? How does it affect
the d.c. voltage?
•
Primary
A
Figure 4
Procedure C
12. Now connect the two 400-turn coils so that
they have maximum voltage and current
output. With the 1000-Ω resistor as a load,
connect the leads of the oscilloscope
between points A and B as shown in Figure
5. What is the shape of the wave form?
What is the waveform between points A
and C? How does the size of the waveform
between A and B compare to that between
A and C?
C
Load
Resistor
B
A
Primary
Secondary
13. In this step, set the triggering of your
Figure 5
oscilloscope again to “LINE”. Connect the
ground lead (often a clip lead) from your oscilloscope to point B in Figure 5. With the probe
at point A, note the waveform. With the probe at point C, again note the waveform and also
any differences between that and the one found at point A. How would you describe this
difference?
14. Now we will make the difference in waveforms useful to us. Connect two diodes into your
apparatus as shown in Figure 6. How does the waveform across the load resistance look?
How does it differ from the waveforms you have seen in previous steps? Is this still alternating current, or is it directional (direct) current?
14
scientific
012-03800A
15. The end result in step 14 is the production of a full-wave rectified signal, one
which is directional in nature, although
it varyies in amplitude over time. We
will now add in a 470-µF capacitor as
shown in Figure 7.
Diode
C
•
Load
Resistor
B
•
A
Diode
16. What is the new waveform across the
load resistor? Do you have d.c., yet?
What is the d.c. voltage you’ve produced?
Primary
Figure 6
Diode
17. Now replace the 1000-Ω load resistance
with a 10-Ω resistor. What is the effect
on the d.c. voltage compared to the
1000-Ω resistance? What is the effect
on the waveform?
C
•
Load
Resistor
B
Capacitor
•
A
Diode
Primary
Figure 7
Analysis
1.
Answer the questions which have been posed along the way during the procedure.
2.
Why do you get such different results if you place the secondary coil(s) on the second or third
leg of the E-shaped core? Think about the magnetic circulation that must take place within
the core.
3.
Compare the results of lowering the load resistance on a half-wave rectified circuit with
lowering the load resistance on a full-wave rectified circuit. If you were to try to stabilize the
output of a power supply, which would be better, a half-wave or full-wave rectified signal?
4.
This experiment has introduced the concept of transformers and power supplies. Further
reading and experimentation can easily begin from here and lead to profitable new understanding.
Data and Calculations
Table 4.1
Number of Turns
Primary
scientific
Secondary
Input V
Input I
15
Load R
Output V
Output I
012-03800A
Appendix
Technical Data
PASCO
Part No.
SF-8609
SF-8610
SF-8611
SF-8612
SF-8613
Number of
Turns in
Coil
Wire
dia. mm
200
400
800
1600
3200
0.9
0.65
0.45
0.33
0.22
Maximum
Current
rms Amperes
DC
Resistance
ohms
0.6
2.2
7.7
35.4
151
2A
1A
0.5 A
0.25 A
0.125 A
16
AC
Impedance
ohms
50 Hz
60Hz
0.64
2.4
8.7
39
164
0.65
2.5
9.1
40.5
170
Selfinductance
mH
0.67
3.2
13.5
52
207
scientific
012-04695D
Thermal Radiation System
Technical Support
Feed-Back
Contacting Technical Support
If you have any comments about this product or this
manual please let us know. If you have any suggestions on alternate experiments or find a problem in the
manual please tell us. PASCO appreciates any customer feed-back. Your input helps us evaluate and
improve our product.
Before you call the PASCO Technical Support staff it
would be helpful to prepare the following information:
To Reach PASCO
For Technical Support call us at 1-800-772-8700 (tollfree within the U.S.) or (916) 786-3800.
• If your problem is computer/software related, note:
Title and Revision Date of software.
Type of Computer (Make, Model, Speed).
Type of external Cables/Peripherals.
• If your problem is with the PASCO apparatus, note:
Title and Model number (usually listed on the label).
Approximate age of apparatus.
A detailed description of the problem/sequence of
events. (In case you can't call PASCO right away,
you won't lose valuable data.)
If possible, have the apparatus within reach when
calling. This makes descriptions of individual parts
much easier.
• If your problem relates to the instruction manual,
note:
Part number and Revision (listed by month and year
on the front cover).
Have the manual at hand to discuss your questions.
012-04399C
3/95
$1.00
Instruction Sheet
for the PASCO
Model SF-8619
MAGNETIC DIP NEEDLE
➃ While in the horizontal position, rotate the entire appa-
Introduction
This compass needle is used to measure the dip angle of
the Earth's magnetic field. However, it may also be used
in its horizontal position as a conventional compass.
ratus to align the compass needle with the axis of banana plug pivot.
➄ Without changing the orientation of the base, rotate
the dip needle at its banana plug connection until the
plastic scale is in the vertical plane.
Setup Procedure
➀ Assemble the two parts of the dip needle by inserting
the banana plug connector into the hole in the black
rod on the stand, as shown in equipment setup diagram.
Theory
The dip needle is a magnetized steel needle which rotates
around its center of mass. When no other magnetic fields
are present, the dip needle will align itself along the direction of the Earth’s magnetic field. The dip angle, or inclination, is the angle between the horizontal plane and the
total Earth magnetic field. By convention, the dip angle
is positive when pointing downwards.
The dip needle apparatus measures the angle, θ between
the vertical plane and the total Earth magnetic field. In
order to obtain the dip angle, subtract θ from 90˚.
The United States Geological Survey maintains a public
domain program for IBM compatible computers which
models geomagnetic parameters including dip angle. The
user inputs their latitude, longitude and elevation and the
program calculates the dip angle. Copies of the program
are free of charge and are available over the Internet via
the following methods:
Equipment Setup
➁ Put the dip needle in a location which is far away from
any ferromagnetic materials and other magnetic fields.
If you place the dip needle on a table, be sure there are
no ferromagnetic supports under the table top.
➂ Rotate the dip needle at its banana plug connection
ftp host:
ftp.ngdc.noaa.gov
gopher host: gopher.ngdc.noaa.gov
login anonymous
no login necessary
www host: http://www.ngdc.noaa.gov no login necessary
The appropriate file is pcgeomag.zip which contains the
source code, executable and documentation files along
with the current magnetic field model.
until the plastic scale is in the horizontal plane.
© 1990 PASCO scientific
This instruction sheet written/edited by: Ann Hanks
better
10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA
Phone (916) 786-3800 • FAX (916) 786-8905 • email: techsupp@PASCO.com
ways to
teach physics
Magnetic Dip Needle
012-04399C
North
Geographic
Pole
θ
South
Magnetic
Pole
Ι
S
N
North
Magnetic
Pole
θ = Angle read from Dip Needle
I = Dip Angle = 90° - θ
South
Geographic
Pole
Dip Angle for Northern California
Copyright Notice
Limited Warranty
The PASCO scientific Model SF-8619 Magnetic Dip
Needle manual is copyrighted and all rights reserved.
However, permission is granted to non-profit educational
institutions for reproduction of any part of this manual
providing the reproductions are used only for their laboratories and are not sold for profit. Reproduction under any
other circumstances, without the written consent of
PASCO scientific, is prohibited.
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the product
which is deemed to be defective in material or workmanship. This warranty does not cover damage to the product
caused by abuse or improper use. Determination of
whether a product failure is the result of a manufacturing
defect or improper use by the customer shall be made
solely by PASCO scientific. Responsibility for the return
of equipment for warranty repair belongs to the customer.
Equipment must be properly packed to prevent damage
and shipped postage or freight prepaid. (Damage caused
by improper packing of the equipment for return shipment will not be covered by the warranty.) Shipping
costs for returning the equipment, after repair, will be
paid by PASCO scientific.
2
012-04393B
11/95
$1.00
Instruction Sheet
for the PASCO
Model ES-9042A
FARADAY ICE PAIL
Introduction
The Ice Pail designed by Faraday is an excellent product
for sampling a charge distribution. It operates on the principle that a charge placed inside a conducting surface will
induce an equal charge on the outside of that surface. For
example, if a charged ball were hung inside a coffee can,
the charge on the outside of the can would equal the
charge of the ball. The charge can be measured with an
electrometer such as the PASCO Model ES-9054B Student Electrometer.
Complete instructions for the operation of PASCO Electrostatic equipment can be found in the ES-9051 Accessory and Demonstration Manual (included with the Demonstration System) and the ES-9055 Laboratory Manual
(included with the Electrostatic Laboratory System)
+
+
The PASCO Model
ES-9042A Faraday Ice Pail
is a wire mesh cylinder measuring 10 cm in diameter by
15 cm deep with a wire
mesh bottom. It is mounted
on three insulating rods
along the outer edge of a
wire mesh shield.
The wire mesh shield not
only ensures complete visibility of the experiment but
also helps eliminate the
problem of stray charges and AC fields.
To prevent stray charges from producing erroneous results it is extremely important that the person performing
the experiment be continually grounded while performing
the experiment. The Ice-Pail needs to be temporarily
grounded prior to starting the experiment.
A charged object such as the PASCO Model ES-9057A
Charge Producers and Proof Plane is placed in the
grounded ice pail (without touching it), and the electrometer indicates the potential between the ice pail and
ground. The greater the charge the greater the potential.
Thus we can easily measure relative charges by varying
the charges in the ice pail and observing the potential indicated by the electrometer.
Charge Producer
Red Clip
Electrometer
+
+
+
+
+
+
+
+
+
Black Clip
+
+
Faraday Ice Pail
+ + ++
- +
+
- ++
+
+ ++
- - - - - -
+
-
+
+
+
+
+
+
Figure 1
Demonstration: Faraday Ice Pail and Charge
Production
Since the Faraday Ice Pail is used so frequently in electrostatic demonstrations, one should examine the relationship between the charge induced on the ice pail by an inserted object and the actual charge on that object. Using
the ice pail, one can then investigate the nature of charging an
object by contact as opposed to charging by induction.
Equipment needed: Faraday Ice Pail, charge producing objects (such as ES-9057A Charge Producers), electrometer
Setup
➀ Connect the electrometer input lead (red alligator clip)
to the ice pail to create a system for measuring
charge. The electrometer ground lead (black alligator
clip) attaches to the shield. (Setup is shown in Figure
1.) Adjust the sensitivity of the electrometer so that
most readings appear in the upper 2/3 of the scale.
© 1993 PASCO scientific
Faraday Ice Pail
012-04393B
➁ Ground the ice pail (i.e., connect the inner pail to the
➤ NOTE:
shield) by touching the inner pail and the outer shield
at the same time with the finger of one hand. (See Figure 2) While conducting the experiment it may be
convenient to continually rest one hand on the upper
edge of the shield. This also grounds the experimenter,
providing the electrometer is connected to both
ground and shield and it allows the ice pail to be easily
grounded whenever necessary.
Closed
➀ The charged object must be inserted at least into the
lower half of the ice pail. Try inserting it, for example,
approximately one centimeter below the top of the pail
and attempt to explain your results.
➁ There may be a small charge retained on the exposed
plastic between the aluminum disk and the aluminum
rod on the charge producers. This residual charge does
not transfer readily when the disk is touched to the
pail. Therefore, (before starting the experiment)
breathe on the exposed plastic of the charge producer
so that the moisture in your breath will tend to remove
any residual charge.
Open
Procedure B
➀ Starting with initially uncharged charge producers,
rub the blue and white materials together. Using the
Faraday Ice Pail, measure the magnitude and polarity
of their charges. By using the results from Procedure
A it is not necessary to touch the charge producer to
the pail. What relationship exists between these
charges produced by contact?
Figure 2
➁ Ground the charge producers and rub them together
➤ NOTE: When removing your finger from the
inner pail after grounding it, make certain that you
are still touching the outer shield. DO NOT remove
your hand from the shield before releasing the inner
pail, as this sequence will not effectively ground the
inner pail.
inside the ice pail. What is the reading on the electrometer. Remove one charge producer and note the
electrometer reading. Replace this charge producer but
remove the other and note the electrometer reading.
➂ Ground the charge producers again. Rub the white
material against the aluminum proof plane. Measure
the magnitude and polarity of the charges. Now rub
the blue material against the aluminum surface and
record your measurements.
➂ Make sure the electrometer reads “zero”, indicating
that there is no charge on the ice pail.
Procedure A
➃ Construct a list of materials such that if a material
➀ Rub two charge producers together to create a charge
lower on the list is rubbed against a material higher on
the list, the charge on the higher listed material is always positive. Such a list is called an electrostatic series.
on them.
➁ Insert one of the wands into the ice pail but do not let
it touch the pail. Note the electrometer reading.
To Reach PASCO
➂ Remove the object from the pail and again note the
For Technical Support call us at 1-800-772-8700 (tollfree within the U.S.) or (916) 786-3800.
electrometer reading.
➃ Insert the wand again, allow it to touch the ice pail and
email: techsupp@PASCO.com
then remove it. Note the electrometer reading.
Tech support fax: (916) 786-3292
➄ Momentarily ground the ice pail and then touch the
object to the pail again. Note the electrometer reading.
Does any charge remain on the object?
What is the conclusion about the induced charge on the ice
pail, as compared to the charge on the charge producer?
2
®
012-05258B
10/94
$1.00
Instruction Sheet
for the PASCO
Model ES-9057A
Charge Producers and Proof Planes
Introduction
The ES-9057A Charge Producers and Proof Planes are
electrostatic components for use with additional equipment from the PASCO Electrostatics System ES-9062A.
The two charge producers are used to generate equal positive and negative charges by contact. The two proof
planes can be used to measure charge density on a
charged object.
The Charge Producers
• If a zero charge is desirable, discharge the charge
producers by touching the conductive disk and
handle to ground. To be sure the disk and handle is
fully discharged, gently breathe on the non conductive neck. The moisture from your breath will help
remove any stray charge.
• Avoid touching the neck during normal use. The oils
from your hands will provide a path for charges to
leak off. Occasionally clean the disk surfaces and the
neck with alcohol.
• When you first use the charge producers, or just after
cleaning, they may not produce charges readily. Rub
the white surface vigorously on the conductive proof
plane disk.
White
surface
Conductive disk
(black)
Blue
surface
Non conductive
neck (white)
The charge producers consist of two wands, one with blue
and one with white material attached to a conductive disk.
Briskly rub the blue and white surfaces of the two charge
producers together. The disk with the white surface will
acquire a positive charge; the disk with the blue surface
will acquire a negative charge. Rub the white surface of
the one charge producer against one of the proof planes.
The white disk will acquire a negative charge, while the
other disk will acquire a positive charge.
➤ NOTE: The Charge Producers are designed to
be used with an electrometer (ES-9054B). They do
not produce sufficient charge for use with a standard electroscope.
The Proof Planes
The proof planes (set of two wands) are conductive disks
attached to insulated handles. They are used to sample the
charge density on charged conductive surfaces.
Conductive disk
(black)
➤ NOTE: Any build-up on the non-conductive neck
can affect results. Clean with alcohol before using.
Non conductive
neck (white)
better
10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA
Phone (916) 786-3800 • FAX (916) 786-8905 • TWX 910-383-2040
ways to
teach physics
012-05258B
Surface of the proof plane disk
IS NOT tangent to the surface
of the conductor.
➤ NOTE: You can then use an electrometer and
a Faraday ice pail (ES-9042A) to measure the
charge density on the proof plane, as shown in
the following illustration.
+
Insert charged proof
plane into Faraday
ice pail
Surface of the proof plane disk
IS tangent to the surface
of the conductor.
+
+
+
NO!
+
+
Ground lead
Signal lead
+
+
+
+
+
+
Electrometer
+
+
YES!
+
+
+
+
+
+
+
charged
conductive
sphere
Other
The conductive disk material is carbon filled black
polycarbonate (about 103 Ω). The non-conductive neck
is white polycarbonate (about 1014 Ω).
Faraday ice pail and shield
Limited Warranty
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of
one year from the date of shipment to the customer.
PASCO will repair or replace, at its option, any part of
the product which is deemed to be defective in material or workmanship. This warranty does not cover
damage to the product caused by abuse or improper
use. Determination of whether a product failure is the
result of a manufacturing defect or improper use by the
customer shall be made solely by PASCO scientific.
Responsibility for the return of equipment for warranty
repair belongs to the customer. Equipment must be
properly packed to prevent damage and shipped
postage or freight prepaid. (Damage caused by improper packing of the equipment for return shipment
will not be covered by the warranty.) Shipping costs
for returning the equipment, after repair, will be paid
by PASCO scientific.
By touching the proof plane to a surface, it will
acquire the same charge distribution as the surface. By
measuring the charge on the proof plane, the charge
density on the surface can be determined. The greater
the charge on the proof plane, the greater the charge
density on the surface where the proof plane made
contact.
When the proof plane is touched to a conductor, the
proof plane becomes part of the conductive surface. If
the effect on the shape of the surface is significant, the
sampling of the charge density will not be accurate.
Therefore, always touch the proof plane to the conductor in such a way as to minimize the distortion of the
conductive surface. The following illustration shows
the recommended method for using the proof plane to
sample the charge on a conductive sphere.
➤ NOTE: To accurately sample charge density,
the conductor should be considerably larger than
the disk of the proof plane and have a relatively
large radius of curvature at the point from which
the sample is taken. However, the proof planes
can be used to test for charge polarity on conductors of any shape.
2
012-04929A
5/92
Instruction Sheet
for the PASCO
Model TD-8550A
THERMOELECTRIC CONVERTER
Introduction
The PASCO scientific Thermoelectric Converter
consists of a thermoelectric heat pump sandwiched
between two aluminum metal legs. Electric current
from the thermoelectric heat pump can drive a small
motor that has a fan attached to its shaft. The Converter can demonstrate the Seebeck effect (discovered
in 1821). In this effect, a temperature difference
across the thermoelectric heat pump gives rise to a
current that drives the small motor (∆T → E). For
example, when one leg is in hot water and the other is
in cold water, the small motor turns the fan. The
Converter can also demonstrate the Peltier effect
(discovered in 1834). When a current is passed
through the thermoelectric heat pump, a temperature
difference results (E → ∆T). One of the legs becomes
warm while the other leg becomes cooler. Finally, the
Converter acts as a “thermal capacitor”. After a
current is passed through the Converter to create the
temperature difference (E → ∆T), flip the switch (∆T
→ E), and the temperature difference causes a current
that drives the small motor.
A) ∆ T ➡ E
scientific
TD-8550A
B) E ➡ ∆ T Thermoelectric
Converter
+ 5V 3A –
2min
MAX
A) ∆ T ➡ E
∆T → E) in order to demonstrate the Seebeck effect
(temperature difference causes electric current).
Connect a source of electric current to the red and
black banana jacks and put the switch in the “down”
position (toward
E → ∆T) to demonstrate the Peltier effect (current
through the thermoelectric heat pump causes a temperature difference).
➧ NOTE: The recommended voltage and current
is 5 Volts and 3 Amps (DC). Do not exceed 8
Volts. Do not run the 5 Volt, 3 Amp current
through the device for more than 2 minutes.
Equipment Needed:
• Cups for hot and cold water
• DC Power supply capable of 5 Volts and 3 Amps
• Patch cords
Recommended Equipment:
• TD-8556 Steam Generator
scientific
TD-8550A
B) E ➡ ∆ T Thermoelectric
Converter
+ 5V 3A –
2min
MAX
A) Place one leg in icewater, one in hot
water. Fan rotates due to ∆ T.
With both legs in same temp water,
fan won't rotate.
B) Connect 5 V, 3 A DC
supply to terminals.
One leg warms,
one cools.
A) Place one leg in icewater, one in hot
water. Fan rotates due to ∆ T.
With both legs in same temp water,
fan won't rotate.
B) Connect 5 V, 3 A DC
supply to terminals.
One leg warms,
one cools.
DO NOT EXCEED 2 MIN OR 8 V!
DO NOT EXCEED 2 MIN OR 8 V!
Figure 1 Switch Position
Figure 1 shows the top portion of the Thermoelectric
Converter. Put the switch in the “up” position (toward
• SF-9584 AC/DC Low Voltage Power Supply or
SF-9582 12 Volt AC/DC Power Supply
• SE-9750 and SE-9751 Banana Plug Patch Cords
Optional Equipment:
• Digital thermometer (such as PASCO Model SB9631 or Model SE-9086)
Theory
A transformation whose only final result is to transform into work heat extracted from a source which is
at the same temperature throughout is impossible.
Lord Kelvin
012-04929A
This was Kelvin’s statement of the Second Law of
Thermodynamics. The second law has been stated in
many, seemingly unrelated ways; but in the end, all
have been shown to be different ways of expressing
the same basic principle. In its most general form, the
Second Law tells us that no physical process will
occur if it decreases the disorder—or entropy—of the
universe. Conservation of energy, as expressed in the
First Law of Thermodynamics, holds for every physical process. But many processes which would conserve energy do not occur. The Second Law describes
this phenomenon.
PASCO
A) ∆T–E scientific
B) E–∆T
+
TD-8550A
Thermoelectric
Converter
–
FAN ROTATES
PASCO
A) ∆T–E scientific
TD-8550A
Thermoelectric
B) E–∆T Converter
+
–
OPERATION
FAN DOES
NOT ROTATE
H2O
(COLD)
Seebeck Effect:
The PASCO Model TD-8550A Thermoelectric Converter is designed to demonstrate this relationship
between the First and Second Laws of Thermodynamics. The procedure used directly illustrates Kelvin’s
statement of the Second Law. The Converter is used
as illustrated in Figure 2. Put the switch in the “up”
position. One leg of the unit is placed in a cup of cold
water and one in a cup of hot water. (Boiling water and
ice water give good results.) Some of the thermal
energy from the hot water is converted into work by
the Converter, and the fan turns. Then the hot and
cold water are mixed together in a larger container.
Both legs of the unit are placed into the container.
Now the fan does not turn.
H2O
(HOT)
SEEBECK EFFECT
(∆T ➞ E)
H2O
H2O
(HOT & COLD MIXED)
Figure 2
Th = Tc
➀ The change in entropy of the hot water, ∆Sh = Qh/
Th, is negative, because of the heat transfer from
the water into the Converter.
The total internal energy of the water is not changed
by mixing the hot and cold together, so there must still
be sufficient energy in the water to turn the fan. But
this would violate the Second Law of Thermodynamics, as stated by Kelvin.
➁ The change in entropy of the cold water,
∆Sc = Qc/Tc, is positive, because of the heat transfer from the Converter into the water.
➂ According to the second law, the total change in
entropy, ∆ST = ∆Sc + ∆Sh, must be positive. There-
➦ NOTE: As a further demonstration, place
fore, the process will only take place if Qc/Tc > Qh/
Th.
one leg in the mixed water (or in ice water) and
one in a container of dry ice to demonstrate that
there is energy available in the mixed water (and
even in ice water).
➃ In order for the fan to be turned, some of the heat
transferred from the hot water must be converted
into work and will therefore not be available to be
transferred back into the cold water. Therefore,
whenever the fan turns, Qh > Qc.
This violation of the Second Law can also be explained in terms of entropy, using the expression ∆S =
Q/T, where ∆S is the change in entropy, Q is the heat
transferred, and T is the temperature at which the heat
is transferred. Considering only the heat transfer
taking place in the cups of water, the following holds:
➄ The equations in steps 3 and 4 can only both be true
if Th > Tc. Once the water is mixed, however, Th =
Tc. Therefore, if the fan were to turn, it would violate the Second Law of Thermodynamics.
2
scientific
012-04929A
Peltier Effect:
During the Peltier effect, a current through the thermoelectric heat pump of the Converter causes a temperature difference. Connect a DC power supply capable of
5 Volts and 3 Amps to the red and black terminals on
the Converter. Put the switch on the Converter to the
E → ∆T (down) position . (For this demonstration,
you do not need to immerse the legs of the Converter
in water.) Turn on the power supply. In a few moments you should be able to feel the temperature
difference of both aluminum legs of the Converter.
PASCO
A) ∆T–E scientific
B) E–∆T
+
TD-8550A
ic
Thermoelectr
Converter
–
FAN ROTATES
➧ NOTE:
DO NOT LEAVE THE POWER
SUPPLY ON FOR MORE THAN TWO MINUTES. DO NOT EXCEED 8 VOLTS.
As an optional exercise, begin with the Converter at
room temperature. Measure the temperature of both
legs. Then, while the current is applied to the Converter, use a digital thermometer to monitor the increase
in temperature of the “hot” leg and the decrease in
temperature of the “cold” leg.
SWITCH IS IN
"DOWN" POSITION
"THERMAL CAPACITOR"
(MODIFIED SEEBECK EFFECT)
Description of Seebeck effect
The Thermoelectric Converter uses a series of thermoelectric cells to convert thermal energy into electrical
energy that will drive the fan. Each cell is a semiconductor device. A simplified diagram of one cell is
shown below.
PASCO
A) ∆T–E scientific
B) E–∆T
+
TD-8550A
ic
Thermoelectr
Converter
–
HOT
H
O
T
TO
POWER SUPPLY
(5 VDC, 3 A)
2 min, 8 VDC MAXIMUM
Thermoelectric
Cell
C
O
L
D
FAN
MOTOR
COLD
PELTIER EFFECT
(E ➞ ∆T)
Thermoelectric Converter Cell (Seebeck effect)
Thermal Capacitor:
During the Seebeck effect, the heat entering the cell
raises the energy level of some of the electrons in the
cell. At the higher energy level, the electrons are no
longer bound in the crystal structure of the semiconductor and are free to move. When they do so, they
leave a vacant place, or hole, in the crystal. Lower
energy electrons, though they can’t move freely within
the material, can jump from hole to hole. In this way,
the holes can also migrate through the semiconductor
material.
After demonstrating the Peltier effect, disconnect the
power supply from the Converter. Put the switch to the
∆T → E (up) position. The temperature difference
caused when the current was applied to the thermoelectric heat pump will now cause the Converter to generate
a current to drive the motor.
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scientific
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The electrons migrate, as shown, through the N-type
semiconductor material and the holes migrate through
the P-type material. (N and P type materials are merely
silicon that is “doped” with special impurities that
enhance electron and hole migration.) The electrons
flow through the external circuit and drive the fan
motor. At the other end of the circuit they reenter the
cell and encounter the holes of the P-type semiconductor. This occurs near the cold end of the cell. The
electrons can therefore drop back into holes, giving up
any excess energy they still retain as heat.
couples, connected in series electrically and in parallel
thermally, are integrated into the thermoelectric heat
pump. The heat pump is packaged between metallized
ceramic plates.
Specifications:
When using the Thermoelectric Converter as a Peltier
device, the power required to produce a given temperature difference depends on the temperature of the hot
side. The hot side must never exceed 135 degrees C,
the melting point of the solder which bonds the Bismuth
Telluride ingots to the plates. Starting at 25 degrees C,
the hot leg temperature increases much more than the
cold leg temperature decreases (about 40 degrees versus
about 8 degrees in 2 minutes). This is because the
power dissipated by the hot side is the sum of the
supplied power and the heat transferred from the cold
side. (If the hot side is held to 25 degrees C, enough
power can be applied to create a maximum temperature
difference of about 67 degrees C.)
As long as the temperature differential is maintained
between the two sides of the cell, the electrons and
holes continue to migrate, and the fan continues to turn.
However, if there is no temperature differential, the
electrons can not recombine with the holes because
there is no place to give up their excess energy. In this
way, the thermoelectric cell is constrained by the
Second Law of Thermodynamics.
Description of Peltier effect
The resistance of the small motor is about 1 ohm.
During the Peltier effect, the electric potential difference causes electrons and holes to migrate from one end
of the N and P type semiconductor material to the other.
The movement of the electrons in the N type semiconductor results in a transfer of internal energy from that
end of the semiconductor, and it cools. The same result
occurs for the P type semiconductor during hole
migration. The heat transfer from the “cold” leg to the
“hot” leg is proportional to the carrier current passing
through the circuit and the number of thermoelectric
cells (couples) making up the thermoelectric pump.
Compatible PASCO Equipment
PASCO offers a complete line of laboratory and
demonstration equipment for thermodynamics. Experiment quantitatively with the mechanical and electrical
equivalents of heat, thermal conductivity, heat capacity,
phase changes in water, and black body radiation.
Check our catalog for these and other products that can
bring PASCO quality into your classroom and laboratory.
Limited Warranty
C
O
O
L
I
N
G
(P-type)
W
A
R
M
I
N
G
PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of
one year from the date of shipment to the customer.
PASCO will repair or replace, at its option, any part of
the product which is deemed to be defective in material
or workmanship. This warranty does not cover damage
to the product caused by abuse or improper use. Determination of whether a product failure is the result of a
manufacturing defect or improper use by the customer
shall be made solely by PASCO scientific. Responsibility for the return of equipment for warranty repair
belongs to the customer. Equipment must be properly
packed to prevent damage and shipped postage or
freight prepaid. (Damage caused by improper packing
of the equipment for return shipment will not be
covered by the warranty.) Shipping costs for returning
the equipment, after repair, will be paid by PASCO
scientific.
DC
SUPPLY
(N-type)
Thermoelectric Converter Cell (Peltier effect)
Construction of the Thermoelectric Heat Pump:
The PASCO Thermoelectric Converter has 71 thermoelectric cooling “couples”. These are made from two
elements of semiconductor, primarily Bismuth Telluride (a quarternary alloy of bismuth, tellurium, selenium
and antimony) heavily doped to create either an excess
(N-type) or deficiency (P-type) of electrons. The
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scientific