MULTISYSTEM TELEVISION PICTURE RECEIVER

摘要

PURPOSE:To simplify the circuit constitution and then realize the multisystem switching without any adjustment and free from the mutual interference, by omitting the special switching power source to carry out the switching of the voice intermediate frequency amplification/detection part. CONSTITUTION:The common terminal of the 1st and 2nd solid state resonators 50 and 51 having different resonance frequencies is connected to one detection end q of voice intermediate frequency amplifier/detector circuit 20 which is formed into an IC. And the terminals of one side of resonators 50 and 51 each are connected to the other detection end r each along with the other terminals earthed respectively. At the same time, the cathodes of diodes 52 and 53 are connected to one end of resistances 54 and 55 each, and the other end of resistances 54 and 55 each is connected to fixed terminals C'' and D'' of switch S2 each with the mobile terminal of switch S2 earthed respectively. Then diodes 52 and 53 are controlled by switch S2, and then the outputs having the frequencies corresponding to resonators 50 and 51 connected between detection ends q and r are extracted steadily through emitter- follower transistor Q.