REMOTE－CONTROLLED_SWITCHER

Published:2009/7/11 3:27:00 Author:May | From:SeekIC

The interface end of Fig. 96-2(a)'s circuit deliver 10 V down the cable, pulses the supply voltage to transmit channel-change commands, and buffers the received video signal.The multiplexer circuit in Fig. 96-2(a) receives power and control signals over the coaxial cable, while driving the cable with the currently selected video signal.The interface circuit (Fig. 96-2(b)) delivers 10 V to the cable and pulses the supply voltage to select one of 8 channels. When the send button is depressed, a digital burst of 1.2 V amplitude (negative) is superimposed on the 12-V line (as a voltage drop). This does not affect the video signal. The multiplexer circuit (Fig. 96-2(c)) consists of a multiplexer and an amplifier. The multiplexer is a Maxim MAX455. The digital code on the supply line is picked off by A1, IC3A, and interfaced to counter IC2, which drives the multiplexer to select the desired video channel.



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