555 point-frequency TV terminal circuit

Published:2011/6/14 20:28:00 Author:TaoXi | Keyword: 555, point-frequency, TV, terminal circuit | From:SeekIC

As the figure 14-17 shows, this circuit is composed of the input circuit, the line frequency synchronization generator, the sample-and-hold circuit, the voltage control delay generator and the RF modulator. The input circuit is composed of the input attenuator RP1 and the emitter follower VT1. The astable multivibrator is composed of the IC2 (555) and RP2, C4.etc, by adjusting RP2, you can make the IC2 to output the pulse waveform which is synchronous as the line scanning frequency 15625Hz, and this pulse is output by pin-3 to add to the trigger port pin-2 of IC1 as the sampling pulse, at last it adds to the e pole of the RF modulator VT2. The sampling and voltage control delay pulse generator is composed of the IC2 (555) and R5, R6, C2.etc.



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