Cable television adds receiving channel circuit

Two functional components are used in the circuit: one is an integrated electronic tuner with AV output (commonly known as a tuner), which can ultimately convert the received
CATV full-channel television signal into a video (Vttko) signal and audio (Audio) ) signal} Another component is the modulator (modulator
), which can modulate the audio and video signals to a certain channel of the TV, and the TV can watch supplementary channel programs. For TVs with audio and video input ports
, you can directly connect to the audio and video output terminals of the tuner without using a modulator.
    The circuit is shown in Figure 1-41, and S is used for band selection. RP was left behind in channel selection. The 7812 three-terminal voltage regulator generates +12V voltage, which is supplied to the tuner
and transmitter respectively.