简易电话定时锁洪利使用电话定时锁可提高电话利用率，避免用电话长时间闲聊。此电话锁利用电话线馈电，无需外加电源。工作原理定时锁的结构与电路如图所示。定时锁电路与电话机串联后再接到外线ＡＢ上。电路中ＢＧ，，ＢＧ。组成受ＩＣ控制的电子开关电路。当挂机时，电... Easy phone timer lock Hong Lee use of the phone lock can improve the phone utilization, to avoid long phone chat. This phone lock uses the telephone line feed, no external power supply. Working principle The timing lock structure and circuit as shown. Time lock circuit and telephone connected to the outside AB in series. Circuit BG ,, BG. IC control by the composition of electronic switching circuit. When on-hook, electricity ...