Systems for supplying unmodulated baseband signals to television receivers

DETAILED DESCRIPTION OF THE INVENTION INCLUDING THE PREFERRED EMBODIMENT Referring to the drawing, a conventional television receiver, only a part of which is shown, includes a video detector 10 and a buffer amplifier 11.
Video detector 10 includes a detector diode 12 connected in circuit with the secondary 13 of a transformer 14, the final tuned video IF transformer, before video detection, of the television receiver.
The output terminal 17 of detector 10 is connected to the input terminal 18 of buffer 11.
Bias for diode 12 is provided via a voltage divider consisting of resistor R1 and R3 connected between a terminal 19 at a positive D.
C.
potential, B, and ground.
Buffer 11 is in the form of a transistor 20 whose collector is connected via a resistor R4 to terminal 19.
A resistor R5 is connected between the emitter of transistor 20 and ground.
As is well known, in normal operation detector 10 detects the video components of the I.
F.
signal.
The audio and video components are separated by buffer 11, the audio signal being derived at the collector of transistor 20 and the video signal being derived at the emitter of transistor 20.
The audio signal (intercarrier sound signal) is supplied to conventional audio I.
F.
and detector circuitry 21, while the video signal is aupplied to conventional video circuitry.
As shown, the audio output of network 21 is applied across a volume control potentiometer 22, the slider of which may be connected to an audio amplifier which, in turn, is connected to a loudspeaker.
Further description of the part of the television receiver shown and its mode of operation is not believed necessary because the part of the receiver shown and its mode of operation are well known to those skilled in the art.
Terminals 23 and 24 to which unmodulated video and audio signals respectively, e.
g.
, from a TV game, can be supplied are provided.
Terminal 23 is connected via a capacitor C1 and transmission gates TG1 and TG2 to input terminal 18.
Resistors R6 and R7 are connected as shown in the FIGURE