电话机加装挂机提醒电路邢观锋电话机使用完后若手机未挂好，不但外面的电话打不进来，而且如果本身是主叫方，邮电局还将继续计时收费。本文介绍一种简单的电话挂机提醒电路，它可装入普通电话机内，在电话挂机时会发出提醒音告诉用户话机已挂好。工作原理挂机提醒电路原... Phone installed hook reminder circuit Xing Guofeng phone after use if the phone is not hung, not only outside the phone can not get in, and if itself is the calling party, the post office will continue to charge the timing. This article describes a simple telephone hook-up reminder circuit, which can be loaded into the ordinary telephone, when the phone hangs will be issued a reminder to tell the user that the phone has hung up. Work on-hook reminder circuit original ...