本报警电路是在95年第4期《停电报警电路的改进》基础上加一延时电路(见下图方框图),就构成了停电、来电报警器。该报警器能在一定时间内停止报警,不需要人工关断,做到了完全自动化。其电路工作原理(见下图):停电报警部分原文已讲述,这里只对来电报警部分做简要说明。去掉原限流电阻R0,将滤波电容C1换为470μ/10V,当来电时通过R1、C3充电,T3截止,T4饱和导通,V_A约为0.3V,D4 The alarm circuit is in the 95th of 4 “power outage alarm circuit improvement” based on the addition of a delay circuit (see the block diagram below), it constitutes a power outage, caller alarm. The alarm can stop alarm within a certain period of time, without manual shut down, so completely automated. The circuit works (see below): blackout alarm part of the original description, here only a brief description of the incoming alarm part. Remove the original current limiting resistor R0, the filter capacitor C1 for 470μ / 10V, when the call through R1, C3 charge, T3 off, T4 saturated turn-on, V_A is about 0.3V, D4