该电路简单实用,适用于各种不设无信号自动延时关机功能的遥控彩电。电路原理: 当电视接收到正常的电视信号时,引同步脉冲进入锁相环音频译码器LM567的第③脚,与译码器的中心振荡频率进行比较。如果译码器振荡频率与行同步脉冲频率稳定一致,则第⑦、⑧脚之间的模拟开关导通,⑧脚为低电平,RP2上无电流流过; The circuit is simple and practical, applicable to all kinds of remote control color TV without automatic signal delay delay function. Circuit principle: When the television receives the normal television signal, lead the synchronous pulse into phase locked loop audio decoder LM567 pin 3, compared with the decoder’s central oscillation frequency. If the decoder oscillation frequency and line synchronization pulse frequency is consistent, the ⑦, ⑧ pin analog switch is turned on, ⑧ pin is low, RP2 no current flow through;