User Guide

Digital Light Meter

Model LT300

Fc

Light Meter

LT 300

RANGE

REL

MAX

MIN

HOLD

RESET

Backlight

Lux

PEAK

Fc

CE

Warranty

EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects in parts and workmanship for one year from date of shipment (a six month limited warranty applies to sensors and cables). If it should become necessary to return the instrument for service during or beyond the warranty period, contact the Customer Service Department at

(781) 890-7440 ext. 210 for authorization or visit our website www.extech.com for contact information. A Return Authorization (RA) number must be issued before any product is returned to Extech. The sender is responsible for shipping charges, freight, insurance and proper packaging to prevent damage in transit. This warranty does not apply to defects resulting from action of the user such as misuse, improper wiring, operation outside of specification, improper maintenance or repair, or unauthorized modification. Extech specifically disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be liable for any direct, indirect, incidental or consequential damages.

Extech's total liability is limited to repair or replacement of the product. The warranty set forth above is inclusive and no other warranty, whether written or oral, is expressed or implied.

Introduction

Congratulations on your purchase of the Extech LT300 Digital Light Meter. The LT300 measures light level (illuminance) to 200,000 Lux (20,000 Fc). The LT300 offers a backlit display, MAX/MIN, Data Hold, Relative, Peak, and Reset features. This instrument is shipped fully tested and calibrated and, with proper use, will provide years of reliable service.

Meter Description

1

2

3

Fc

15

Light Meter

LT 300

10. Fc foot candle button

16

4

5

6

7

RANGE

MAX

MIN

REL

HOLD

11

12

13

14

RESET

Backlight

PEAK

CE

8

Lux

Fc

15. Photo sensor dome

1

9 10

Notes: Protective sensor cap not shown. Battery compartment, Tilt Stand, and Tripod Mount are located on the rear of the instrument. The protective rubber jacket must be removed from meter to access battery compartment.

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LT300 V1.0 5/06

Operation

Light sensor

1. The light sensor is permanently attached to the meter by the coiled cable.

2. Remove the protective cap by unsnapping it to expose the white domed light sensor. When the sensor’s protective cap is removed, the white domed light sensor lens will begin to capture light. Replace the cap when the meter is not in use.

Turn Power ON or OFF

Press the button to turn power on or off. If the display does not switch on, check that the 9V battery is installed and is fresh.

Selecting Lux or Foot candle units of measure

Press the LUX button to select lux units or the Fc button to select foot candle units.

Measurement Procedure

1. Remove the protective cap from the sensor so that the white domed light sensor is exposed to the light. For overhead lighting, the sensor can be placed on a desk or table top. A tripod mount and a tilt stand are located on the rear of the meter for convenience.

2. The display will indicate the light level in Fc or Lux.

3. Press the RANGE button to select the range that provides the maximum resolution. If the ‘OL’ appears the light measurement is out of range. Select another range using the

RANGE button.

4. Press the backlight button to illuminate the LCD display if needed.

MAX/MIN

The Max/Min function allows for recording and display of the maximum and minimum light levels over time. display and hold only the highest reading. The display will update only when a higher reading is measured. and hold only the lowest reading. The display will update only when a lower reading is measured now display the current reading, but will continue to record the highest and lowest values.

5. To exit the MAX MIN mode, press and hold the MAX/MIN button until the MAX and

MIN icons completely disappear.

Data Hold

Press the HOLD button to freeze the displayed reading. The ” MANU HOLD” hold icon will appear on the display. Press the HOLD button again to return to normal operation. When the Data Hold function is enabled the analog bar graph will continue to display level changes.

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LT300 V1.0 5/06

Peak Hold

The Peak Hold feature allows the meter to captures light pulses that rise or fall down to

10µs.

1. Press and hold the PEAK button until CAL appears in the display.

2. Momentarily press the PEAK button. The ‘P

MAX

’ icon will appear on the LCD. The meter will then measure and display any light pulses. The display will hold the results until a higher pulse appears. the

MIN”

values.

4. To exit the Peak Hold mode, press and hold the PEAK button until the ‘P

MAX

’ or ‘P

MIN

’ icon disappears.

Relative mode

Measurements can be displayed as a difference between the measured light level and a stored reference value. To store a reading as a reference, press the REL button when the desired reference measurement is on the LCD (the REL icon will switch on). All subsequent displayed readings will be “relative” to the stored reference value. For example, if the reference value is 100 and the actual light level is 125, the meter will display 25. To view the reference value, press the REL button again so that the REL icon begins to flash. The displayed value will be the reference value. To exit the Relative mode, press and hold the REL button until the REL icon disappears.

RESET

Press the RESET button to clear the memory and exit from REL, HOLD, PEAK and

MAX/MIN. The RESET will also reset the auto power off timer.

Backlight

Press the “ “ button to turn the backlight on. Press again to turn it off.

Maintenance

Cleaning and storage

1. The white plastic sensor dome should be cleaned with a damp cloth when necessary.

Use only a mild soap if needed. Do not use solvents, abrasives, or harsh detergents to clean the dome.

2. Store the meter in an area with moderate temperature and humidity (refer to the operating and storage range in the ‘Specifications’ section).

Battery Replacement

When the battery power begins to fail the low battery symbol “ ”will appear on the LCD.

Replace the 9V battery by first removing protective jacket that encases the meter. Remove the rear (center) battery compartment screw to access the battery compartment. Ensure that the compartment cover is securely fastened and that the protective jacket is properly installed before using the meter.

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LT300 V1.0 5/06

Specifications

Ranges and Resolution

Lux

40.00, 400.0, 4000, 40.00k, 200.0kLux

Foot candle (Fc)

40.00, 400.0, 4000, 20.00kFc

Accuracy

± (5% Rdg + 0.5% Full Scale)

± (5% Rdg + 0.5% Full Scale)

General Specifications

Display

Over range indication

Multi-function 3-3/4 (3999) digit LCD with Bargraph indicator

LCD displays ‘OL’

Spectral response

Spectral accuracy

CIE photopic (CIE human eye response curve)

CIE V

function (f

1

ï 6%)

Measurement Repeatability ±2%

Temperature coefficient ±0.1% per o

C

Sampling rate 13.3 times per second (bargraph); 1.3 times per second (digital display)

Photo detector

Peak Hold

Operating conditions

Storage conditions

Silicon photo-diode with spectral response filter

Capture light peaks to 10µS

Temperature: 32 to 104 o

F (0 to 40 o

C); Humidity: < 80% RH

Temperature: 14 to 140 o

F (-10 to 50 o

C); Humidity: < 80% RH

Dimensions

Weight

Low battery indication

Power supply

6.5 x 3.0 x 1.7" (165 x 76 x 43mm)

Approx. 14.2 oz. (403g) with battery installed

“ ” appears on the LCD

9V battery

Calibration and Repair Services

Extech offers repair and calibration services for the products we sell. Extech also provides NIST certification for most products. Call the Customer Service Department for information on calibration services available for this product. Extech recommends that annual calibrations be performed to verify meter performance and accuracy.

Support line (781) 890-7440

Technical support: Extension 200; E-mail: [email protected]

Repair & Returns: Extension 210; E-mail: [email protected]

Product specifications subject to change without notice

For the latest version of this User’s Guide, Software updates, and other up-to-the-minute product information, visit our website: www.extech.com

Extech Instruments Corporation, 285 Bear Hill Rd., Waltham, MA 02451

Copyright © 2006 Extech Instruments Corporation.

All rights reserved including the right of reproduction in whole or in part in any form.

LT300 V1.0 5/06

5

Appendix

Typical Light Levels

Lux Foot

Candles

Factories

Store

Indoors

Corridor/Stairs

Lux Foot

Candles

Home

Passages 150-200 15-20 Recreational

Activities

200-300 20-30 Drawing

Table

Visual 300-500 30-50 Makeup

750-1,500 75-150 Typesetting: Inspection Work 500-1,500 50-150 Reading,

1,500-3,000 150-300 Electronic 1,000-2,000 100-200 Sewing

Restaurant

75-100 7-10

Office

Indoor Emergency Stairs

Conference,

Reception Room

150-300 15-30 Entrance,

Wash Room

Room,

Dining Table

Hospital

30-75 3-7 Emergency Stairs

75-100 7-10 Stairs

Room,

Warehouse

200-750 20-75 Medical

Room

Window,

Packing Table

1,500-3,000 150-300 Storefront, Show Window

Spectral Sensitivity

5,000-10,000 500-1000 Eye Inspection s p o n e

R e s e t i v

R e l a

0.4

0.2

0

1

0.8

0.6

400 450 500 550 600 650 700

Wavelength (nm)

- - - - - Light Meter Response

_____

CIE Response

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LT300 V1.0 5/06