Subscriber stations with additional devices - have voltage monitoring circuit which disconnects devices when battery voltage drops below specified limit

摘要

The stations are supplied through subscriber lines, and the additional devices are e.g. number stores. They are a part of a telephone system. When the subscriber line is not switched through, the additional devices are supplied by an additional voltage source. A voltage monitoring circuit (UW) becomes operative when the receiver is lifted, and when the additional voltage source (B) voltage drops below a specified limit, it disconnects the additional devices (RAM).