RF switch

United States Patent [191
[11]
[45]
Nakagawa et al.
[541
RF SWITCH
Yoshiaki Nakanishi, Kyoto, both of
358/188, 186, 189; 455/217, 300, 301, 317;
333/103; 455/78, 83
References Cited
U.S. PATENT DOCUMENTS
4,276,562 6/1981 Stewart et a1.
4,312,016 1/1982 Glaab et a1.
358/181
358/188
4,349,750 9/1982
4,361,854 11/1982
4,424,591
1/1984
358/181
358/188
333/103
4,535,360
8/1985 Briley et al. ..
4,542,300
9/1985
ABSTRACT
contained. To the board, two input ends connected
respectively to an F-connector and an RCA plug and
one output end connected to an antenna terminal of a
TV receiver by an F-plug are connected. On the board,
high-pass ?lters connected in a cascade fashion are
formed, of which input is connected to one input end
connected to the F-connector. The ?lter in each stage is
earthed at the output side thereof through correspond
ing switching transistors. When a power switch of a
main unit of a picture processing apparatus is turned on,
a superposed signal of a DC signal and an RF signal is
given to the remaining input end from the main unit
Thompson .......................... .. 358/86
Geuns ..... ..
Wolfe ......................... ..
Boardman .............. ..
[57]
An RF switch comprises a housing in which a board is
[73] Assignee: Nintendo Co., Ltd., Kyoto, Japan
[21] Appl. No.: 761,744
Aug. 1, 1985
[22] Filed:
[5 11 Int. Cl.4 ........................................... .. H04N 5/268
[52] US. Cl. .................................................. ,. 356/181
[58] Field of Search ................. .. 358/83, 86, 181, 187,
6/1975
May 17, 1988
Primary Examiner—Tommy P. Chin
Japan
3,889,050
4,745,478
Attorney, Agent, or Firm—Larry A. Jackson
[75] Inventors: Katsuya Nakagawa, Kusatsu;
[56]
Patent Number:
Date of Patent:
358/86
Nagatorni .......................... .. 333/103
FOREIGN PATENT DOCUMENTS
1199807
9/1965
0109078
0028775
8/1980 Japan ................................. .. 358/181
2/1984 Japan ................................. .. 358/181
Fed. Rep. of Germany .... .. 358/181
through the RCA plug and a coaxial cable. In the RF
switch, the DC signal is taken out from the superposed
signal, thereby respective switching transistors are
turned on. Accordingly, a TV signal from a TV antenna
is ?own into the earth, while the RF signal from the
main unit it given to the output end through a diode
biased in a forward direction by the DC signal. When
the power switch of the main unit is in “off”, the high
pass ?lters will not be inactivated and the TV signal
from the TV antenna is thus given to the output end.
14 Claims, 2 Drawing Sheets
CONNECTOR
ROM CARTRIDGE
US. Patent
May 17,1988
FIG]
32
3O
Sheet 1 of2
4,745,478
1
4,745,478
RF SWITCH
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an RF switch. More
speci?cally, the present invention relates to an RF
2
and the DC control signal are applied to the RF switch
from the main unit. The circuit means for inactivating
the ?lter means is actuated by the DC control signal,
and thus the TV signal at the ?rst input end is not trans
mitted to the output and the TV signal from the main
unit (i.e., second TV signal) is applied to the output end
by the transmitting circuit means and thence to the
antenna terminal of the TV receiver. At this time, since
switch for switching over an antenna input of a TV
the ?lter means has been inactivated, spurious radiation
receiver when the TV receiver receiving a TV signal
from an antenna is used as a monitor for a picture pro 0 caused by the RF signal from the main unit of the pic
cessing system, for example, such as a personal com
ture processing apparatus is effectively prevented from
puter, a video game system or the like.
leaking back to the ?rst input end.
2. Description of the Prior Art
According to the present invention, since the source
A video game system and a personal computer, for
of TV signal can be automatically changed by simply
example, such as “ATARI 2600” (Trademark) and
turning on the power switch of the main unit of the
“COLECO VISION” (Trademark) which utilize a
apparatus supplying the second TV signal, such as a
domestic TV receiver as a monitor are well known. In
personal computer or video game apparatus, a manual
such video game and computer systems and the like, the
switching operation is no longer required each time the
TV signal input from a TV antenna or a VTR must be
apparatus is to be used.
switched over to an RF signal (a TV signal) for the
In the preferred embodiment, the RF switch is
game or computer system. The switchover is necessary
formed on a board contained in a housing. The housing
to avoid interference between the TV signals from the
in turn is formed with two different, optional cable
antenna and for the monitor as well as from spurious
guide portions for guiding the connecting cable from
radiation of the monitor’s RF signal.
Accordingly, in the past, one of the two TV signals
has been selectively connected to the TV receiver, in
general, by a mechanical switch, for example, a slide
switch. Typically, the slide switch is connected to hang
loosely in the vicinity of an antenna terminal of the TV
receiver. When using, for example, the game system,
the main unit the second TV signal apparatus in the
most convenient direction. One of the cable guide por
tions routes the cable from the housing in a ?rst direc
tion and the other guide portion routes the cable in a
second and different direction, so that the most suitable
cable direction can be selected according to the ar
ranged positions of the main unit supplying the second
the slide switch must be switched over by reaching,
sometimes only by feel, around to the back side of the
TV receiver to manually operate the switch. This oper
ation is not only troublesome but also dangerous be
TV signal, the TV antenna and the TV receiver or
monitor.
A principal object of the present invention is, there
BRIEF DESCRIPTION OF THE DRAWINGS
These objects and other objects, features, aspects and
cause of the high voltage equipment on the back side of 35 advantages of the present invention will become more
apparent from the following detailed description of the
the TV receiver.
embodiment when taken in connection with the accom
SUMMARY OF THE INVENTION
panying drawings.
fore, to provide an RF switch which is capable of 40
switching over an antenna input automatically to a TV
receiver from another video source, such as a picture
processing system, when the TV receiver is used as a
monitor.
FIG. 1 is a schematic perspective view showing a
video game system incorporating the RF switch of the
present invention.
FIG. 2 is a circuit diagram showing the embodiment
Another object of the present invention is to provide 45 of FIG. 1.
an RF swtich that facilitates a change in circuit connec
tions between RF circuit cables.
The present invention is, in brief, an RF switch com
prising ?rst and second inputs and an output. A ?rst
input end is connected for receiving a ?rst TV signal. A
?lter means is connected between the ?rst input end and
FIG. 3 is a graph showing an attenuation versus fre
provided for inactivating said ?lter means in response to
the DC control signal when applied to the second input
end, and for transmitting said second TV signal to said
quency characteristic for explaining an aspect of the
operation of the embodiment of FIG. 2.
FIG. 4 is a circuit diagram showing a modi?ed por
tion of another embodiment.
FIG. 5 is a circuit diagram showing a modi?ed por
tion of another embodiment of FIG. 2.
FIG. 6(A) is an illustrated plan view of the structure
of the RF switch embodiment of FIG. 1; FIG. 6(B) is a
left side view; FIG. 6(C) is a right side view; and F IG.
6(D) is a front view.
FIG. 7 is an exploded perspective view showing the
output.
housing of FIGS. 6(A), (B), (C) and (D).
the output. A second input end is adapted for receiving
a second TV signal superposed on a DC control signal,
to an output of the ?lter means, and circuit means are
For example, when a power switch of a main unit of
DESCRIPTION OF THE PREFERRED
an apparatus providing a second TV signal is “oft”, the 60
EMBODIMENT
second TV signal is not present and hence is not applied
to the RF switch. Accordingly, the ?lter means is not
FIG. 1 is a schematic perspective view showing a
inactivated and in that state, the ?rst TV signal, for
video game system in which the RF switch 24 of the
example, from the TV antenna or a VTR is passed to an
present invention is incorporated. The present inven
antenna terminal of the TV receiver through the output 65 tion will be described in this video game system envi
of the RF switch.
ronment. However, it is noted that the present invention
On the other hand, when the power switch of the
may in general be utilized in systems using a domestic
main unit is turned on, the superposed second TV signal
TV receiver as a monitor for an information processing
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system or a picture processing system such as a personal
computer.
To a main unit 10 of such a game apparatus, a com
mercial power source is supplied through an AC
adapter 12. To the main unit 10, two controllers 14 are
connected by suitable connecting cables. Also, on the
main unit 10, a cartridge receiving port 16 for a pro
4
trol voltage are outputted to the coaxial cable 22, which
is connected to the RF switch 24.
In the RF switch 24, a ?rst input end 24a is connected
to an F-connector 48 which in turn is connected to the
TV antenna 32 through the feeder cable 30 (FIG. 1). A
second input end 24b receives the above-mentioned
coaxial cable 22 and an output end 240 is connected to
an F-plug 62 by a coaxial cable.
gram ROM cartridge (see FIG. 2) for the game is pro
vided. Accordingly, in the main unit 10, the TV signal
for the game is generated according to the content of
the inserted ROM cartridge. On the main unit 10, a
Between input end 240 and the output end 24c, three
stage high-pass ?lters 50a, 50b and 50c are connected in
cascade. In this embodiment, the high-pass ?lters
power switch 18 and a reset switch 20 are further pro
5011-500 are constructed as a rr-type ?lter. The output
vided. The power switch 18 is for turning on the power
sides of respective ?lters 50a. 50b and 500 are selectively
source of the main unit 10 and the reset switch 20 is for
grounded through switching transistors 52a, 52b and
resetting the content of the game.
15 52c to disable, i.e., inactivate, the ?lters. These switch
As an example of such a video game system, refer
ing transistors 52c-52c are connected to a DC voltage
ence is made to products available under the names
line 54 via suitable current-limit resistors. The DC volt
“Family-Computer” (trademark) or “Nintendo Enter
age line 54 is connected to the above mentioned second
tainment System” (trademark) manufactured by the
input end 24b via a choke circuit 56 including a choke
assignee of the present invention.
coil 56a and a by-pass capacitor 56b. The choke circuit
The main unit 10 is connected to RF switch 24
56 serves as a highfrequency blocking circuit for block
through a coaxial cable 22. The RF switch is connected
ing the TV signal present at the second input end 2412
to an antenna terminal of a conventional TV receiver 28
from ?owing back to the ?rst input end 24a and causing
through a coaxial cable 26. The RF switch 24 is further
connected to a TV antenna 32 by a feeder cable 30. The
RF switch 24 operates to switch over the TV signal
applied to receiver 28 from the TV antenna 32 and to
RF interference to be radiated therefrom.
the TV signal from the game system main unit 10 so as
to select either of them for connection to the TV re
ceiver 28.
Referring to FIG. 2, the cartridge port 16 of the main
unit 10 is provided with a connector 34. Plugged into
the connector 34 is a connector 360 of the ROM car
tridge 36. In the embodiment, the connector 36a is
formed as a male part arranged with a plurality of pins 35
Between the output end 24c and the second input end
24b, a series connection of a bias circuit 58 and a switch
ing diode 60 are connected. The bias circuit 58 includes
a parallel circuit of a resistor 58a and a capacitor 58b,
and develops a DC voltage to bias the diode 60 as well
as prevent a direct short-circuit between the input end
24b and the output end 24c. The capacitor 581) is for
passing the TV signal from the game main unit 10 at the
input end 241) to the output end 24c through the diode
60.
The output end 24c of RF switch 24 is connected to
and the connector 34 is formed as a female part to re
the F-plug 62 through a coaxial cable. The F-plug 62 is
ceive these pins. The connector 34 is connected to a
CPU 38 and a PPU 40, for example, by ?at cables or
other wiring. The CPU 38 and the PPU 40 are con
connected to an F-connector (not shown) of the an
tenna terminal of the TV receiver 28.
For the purpose of shielding respective inner conduc
nected mutually as well as to an I/O interface 42, to
which two controllers 14 are connected.
tors, outer conductors of the coaxial cable 22, the F
connector 48 and the F-plug 62 are all grounded.
The CPU 38 provides video picture data necessary to
In operation, when the RCA plug 46 is not connected
play the game to the PPU 40 based upon game program
to the main unit 10, or when it is connected but the
data from a ROM (not shown) included in the ROM
power switch 18 of the main unit 10 is off, that is, when
cartridge 36 and control signals from the controllers 14; 45 the TV receiver 28 (FIG. 1) is not used as the monitor
As the CPU 38, a microprocessor, for example, such as
for the game system, the input end 24b has no applied
an integrated circuit “Z80A” made by Zilog Inc. may
be used. The PPU 40 is for generating the TV signal of
NTSC standard, for example, based upon the picture
data from the CPU 38. As the PPU 40, for example, an
integrated circuit “2C03” made by Nintendo Co., Ltd.
may be used.
The picture signal from the PPU 40, that is, the TV
signal is applied to the coaxial cable 22 through the I/O
interface 42. To the coaxial cable 22, a DC control
voltage, for example, of about 3 volts from the AC
adapter 12 (FIG. 1) is also applied through the power
switch 18, a protective resistor 43 and a choke coil 44.
signal whatever. Accordingly, the switching transistors
52c-52b remain off and the diode 60 is also off. There
fore, the respective ?lters 50a-50c are not disabled. In
this state, the TV signal from the TV antenna 32 (FIG.
1) or a VTR (not shown) applied at the F-connector 48
to the ?rst input end 24a, is transmitted to the output
end 24c through the active three-stage ?lters 50a-50c
and thence to the TV receiver 28 (FIG. 1) therefrom
through the F-plug 62. Thus, when the ?lters 50a-50c
are not disabled, the TV signal from the ?rst input end
240 is given to the TV receiver 28 almost without atten
source (Vcc) of the main unit 10 even if the main unit 10
uation as shown by a plotted line X in FIG. 3.
When the RCA plug 46 is connected to the main unit
10 and the power switch 18 of the main unit 10 is turned
at RCA plug 46 is erroneously short-circuited by an
operator. A resistance value of the protective resistor 43
is selected relatively high such that it allows current
on, the superposed RF signal for the game, generated
by the content of the ROM cartridge 36 and PPU 40,
and the DC control signal applied through the power
The protective resistor 43 is for protecting the power
suf?cient to turn on switching transistors 52a-52c to be
switch 18, protective resistor 43 and choke coil 44 are
supplied to the RF swtich 24. The choke coil 44 pre 65 outputted to the coaxial cable 22. The superposed RF
vents the TV signal from the PPU 40 from flowing into
the power line through the AC adaptor. Thus, the su
perposed TV signal from the PPU 40 and the DC con
and DC control signals are applied to the second input
end 24b through the inner conductor of the coaxial
cable 22. The DC control signal component is coupled
5
4,745,478
6
to respective switching transistors 52a-52c through the
ever, it is preferably constructed separately from these
choke coil 56a and the DC voltag eline 54. Thus, the
units as shown in FIG. 1.
switching transistor 52a-52c are turned on and the out
put sides of the corresponding ?lters 50a-50c are
grounded. Therefore, the ?lters 50a-50c are disabled.
Accordingly, even if the TV signal is present at the ?rst
input end 240 through the F-connector 48, the TV sig
nal will be grounded through the inactivated ?lters
Now, referring to FIGS. 6 and 7, the structure of the
RF switch 24 will be described in detail. The RF switch
24 comprises a housing 64 having alower shell 64a and
an upper shell 64b mated therewith. The housing 64 is
formed in a plan rectangle and provided therein with a
board 66 having the ?lter circuit and associated compo
50a-50c, namely, through the switching transistors
nents as shown in FIG. 2 or FIG. 4 mounted thereon.
52a-52c and substantially attenuated as shown by a
The coaxial cable 22, the F-connector 48 and the F-plug
62 (FIG. 2) are connected to the board 66. The F-con
plotted line Y in FIG. 3. The TV signal at input end 24a
thus does not appear at the output end 24c.
At this same time, the TV signal present at the second
input end 24b is blocked by the choke circuit 56 so it
does not leak back to the ?rst input end 240 through the
?lters 50a—50c.
The DC control signal (DC voltage) present at the
second input end 24b is applied to the diode 60 through
the resistor 58a of the bias circuit 58, generating a for
nector 48, the coaxial cable 22 and the F-plug 62 are
connected respectively to the ?rst input end 24a, the
second input end 24b and the output end 24c as previ
ously described.
As clearly understood from FIG. 7, housing 64 is
formed with holes 68 and 70 that accommodate the
insertion of the F-connector 48 and the F-plug 62, and
a hole 72 that serves to guide coaxial cable 22 to the
ward voltage across the diode 60 of approximately 0.7 20 outside of the housing 64. Along one of the longer sides
of the housing shells 64a and 64b, channels 740 and 74b
volts. Therefore, the diode 60 is turned on. The TV
are formed. Then, in the channels 74a and 74b, a plural
signal at the second input end 24b is passed through the
ity of protrusions 76a, 76a—and 76b, 76b—are formed
diode 60 via the capacitor 58b of the bias circuit 58 to
in a staggered fashion as shown in FIG. 6(D).
the output end 24c, since the diode 60 is in a low im
In the example shown in FIG. 6(A), the coaxial cable
pendance “on” state. The TV signal (RF signal) from
22
is guided out of the housing in an orthogonal direc
the main unit 10 thereby appears at the output end 240
tion relative to the long side of the rectangular housing
and is applied to the antenna terminal (not shown) of the
64. But, depending upon the arrangement of the main
TV receiver 28 through the F-plug 62 as in the previous
case.
Thus, by turning on or off the power switch 18 of the
main unit 10, the RF switch changes the TV signal
available at the output end 24c. Accordingly, when the
unit 10 and the TV receiver 28, there may be a case in
30 which this con?guration of the coaxial cable 22 is im
practical. Accordingly, in the embodiment, the coaxial
cable 22 is adapted to be guided out of the housing 64
parallel to the long side thereof by utilizing the channels
TV game apparatus is not being used, a TV broadcast
74a and 74b as shown by the doube dotted line in FIG.
may be received by the TV receiver 28. To play the TV
6(A). Coaxial cable 22 is held in the channel 74 by the
game, the power switch 18 of the main unit 10 is turned
protrusions 76a and 76b formed in the respective chan
on to automatically disable the TV broadcast signal and
nels.
to cause only the TV game signal from the main unit 10
Although the present invention has been described
to be applied to the TV receiver 28.
and illustrated in detail, it is clearly understood that the
FIG. 4 is a circuit diagram showing a modi?ed form
same is by way of illustration and example only and is
of certain portions of the main unit 10 of the FIG. 2
not to be taken by way of limitation, the spirit and scope
embodiment. In the FIG. 4 embodiment, the I/O inter
of the present invention being limited only by the terms
face 42 includes an RF modulation circuit 42a to which
of the appended claims.
an output of the power switch 18 is applied through a
What is claimed is:
slide switch 19 and through a conductive printed circuit 45
1. An RF switch adapted to selectively connect one
pattern 36a formed in U-shape letter at an edge of the
of two video source signals to a television monitor,
plug-in board of the ROM cartridge 36. The slide
comprising:
switch 19 is for turning off the power source to the RF
a ?rst input for receiving a ?rst television signal;
modulation circuit 420 while the power switch 18 re
a second input for receiving a second television signal
mains in its ON state. The power switch 18 and the slide 50
from an auxiliary source in which the auxiliary
switch 19 are connected to each other through the
source is adapted to produce a DC control signal
conductive pattern 36b only when the connector 36a of
superimposed on the second television signal;
the ROM cartridge 36 is plugged into the connector 34
an output adapted to be connected to said television
of the main unit 10. The DC voltage Vcc thus cannot be
monitor;
applied to the RF modulation circuit 420 even if both 55
a plurality of inductive-capacitive ?lters connected in
the power switch 18 and the slide switch 19 are ON
cascade between said ?rst input and said output,
when ROM cartridge 36 is detached. An RF signal
each said inductive-capacitive ?lter having an asso
passing from the second input end 24b to an output end
ciated transistor switch including a control input
240 is cut off automatically, and the TV signal from the
and connected to provide an impedance path
?rst input end 24a is applied to the output end 24c.
switchable to a low impedance state so as to
FIG. 5 is a circuit diagram showing a modi?ed exam
ground each said ?lter in response to a control
ple of the embodiment of FIG. 2 especially the RF
voltage applied to said control input;
switch. In the embodiment shown, ?lters 50a, 50b and
an RF choke connecting said control input of said
50c are constructed as a T-type ?lter. Other aspects are
associated transistor switch of each said inductive
identical with FIG. 2 so the duplicate description will 65
capacitive ?lters to said second input for causing
be omitted here.
said associated transistor switch to switch to said
The RF switch 24 described above may be incorpo
low impedance state in response to said DC control
rated into the main unit 10 or the TV receiver 28. How
signal superimposed on said second television sig
7
4,745,478
8
nal so as to inactivate said inductive-capacitive
6. A video game system in accordance with claim 2,
?lters and thereby isolate said ?rst television signal
from said output; and
a voltage controlled signal transmitting circuit con
nected between said second input and said output,
wherein said main unit includes a power switch and a
said transmitting circuit comprising a diode con
nected in series with a parallel resistive-capacitive
network, said diode having a high impedance re
verse bias state in the absence of said DC control
signal at said second input so as to isolate said out
put from said second input, and said diode being
responsive to a bias voltage developed across said
resistive-capacitive network in response to said DC
control signal to assume a low impedance forward
biased condition that transmits the second televi
sion signal through said resistive-capacitive net
work and through said diode to said output for
application to the television monitor.
2. A video game system comprising:
means for supplying a ?rst TV signal;
20
a main unit for generating a second TV signal for
displaying a video game, said main unit including
means for generating a DC control signal that is
superimposed on said second TV signal;
an RF switch having a ?rst input end for receiving
said ?rst TV signal and a second input end for 25
receiving said second TV signal and said superim
posed DC signal, and an output end adapted to be
connected to a television monitor;
a plurality of inductive-capacitive ?lters connected in
cascade fashion to form a signal path between said
?rst input end to said output end of said RF switch;
voltage controlled switching means for inactivating
said ?lters having a ?rst and at least a second volt
age controlled semiconductor switching element
for selectively inactivating said ?lters to block said
?rst TV signal from said output end in response to
said DC control signal superimposed on said sec
ond TV signal, said ?rst semiconductor switching
element being connected between one of said in
ductive-capacitive ?lters and ground, and said sec
superposing means for superposing said DC signal on
said second TV signal for video game when said power
switch is turned on.
7. A video game system in accordance with claimm 6,
wherin said superposing means includes a high fre
quency blocking means for preventing said second TV
signal for video game to ?ow into a commercial power
source from said main unit through said power switch.
8. A video game system in accordance with claim 7,
wherein said high frequency blocking means includes a
choke coil.
9. An RF switch comprising:
a ?rst input end for receiving a ?rst TV signal;
an output end;
a plurality of inductive-capacitive ?lters connected in
a cascade fashion to form a ?ltered signal path
between said ?rst input end and said output end;
voltage controlled switching means for controlling
said ?lter means and including a ?rst semiconduc
tor switching element connected between one of
said inductive-capacitive ?lters and ground and at
least a second semiconductor switching element
connected between another of said inductive
capacitive ?lters and ground;
a second input end for receiving a second TV signal
and a DC control signal superimposed on said sec
ond TV signal;
said ?rst and second semiconductor switching ele
ments being turned on in response to said DC con
trol signal to cause said ?ltered signal path of said
inductive-capacitive ?lters to be connected to
ground thereby inactivating said inductive-capaci
tive ?lters to block said ?rst TV signal; and
voltage controlled transmitting means for transmit
ting said second TV signal to said output end in
response to said second TV signal and said DC
control signal being applied to said second input
end.
10. An RF switch in accordance with claim 9,
wherein said transmitting means includes a diode con~
ond semiconductor switching element being con
nected
between said second input end and said output
nected between another of said inductive-capaci
end.
tive filters and ground, said ?rst and second semi
11. An RF switch in accordance with claim 10,
conductor switching elements being turned on and
wherein said transmitting means includes a capacitor
45
off in response to said DC control signal superim
connected between said second input end and said di
posed on said second TV signal such that when on
said ?rst and second semiconductor switching ele
ode, and a resistor connected in parallel with said ca
pacitor for preventing a direct short-circuit between
ments inactivate said inductive-capacitive ?lters by
said second input end and said output end and for pro
connecting said signal path to ground; and
viding a bias in a forward direction to said diode.
voltage controlled transmitting means for transmit 50
12. An RF switch in accordance with claim 9, which
ting said second TV signal to said output end of
said RF switch in response to said DC control
signal superimposed on said second TV signal.
3. A video game system in accordance with claim 2,
wherein said transmitting means includes a diode con
nected between said second input end and said output
end.
further comprises means for blocking the transmission
of said second TV signal from said second input end to
said ?rst input end.
13. An RF switch in accordance with claim 12,
wherein said blocking means includes a choke coil con
nected to said second input end at one end thereof and
a by-pass capacitor connected between another end of
4. A video game system in accordance with claim 3,
said choke coil and a ground.
wherein said transmitting means includes a capacitor
14. An RF switch in accordance with claim 9, which
connected between said second input end and said di
further comprises a housing, and a circuit board con
ode, and a resistor connected in parallel with said ca
tained within said housing, ?rst and second input ends
pacitor for preventing a direct short-circuit between
and said output end being connected to said circuit
said second input end and said output end and for pro
board, a connecting cable joined to said second input
viding a bias in a forward direction to said diode.
end, and said housing comprising ?rst and second cable
5. A video game system in accordance with claim 2, 65 guide portions for selectively guiding said connecting
which further comprises means for blocking the trans
cable from said second input end in either of two differ
mission of said second TV signal for video game to said
ent optional directions relative to said housing.
?rst input end from said second input end.
III
1'!
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