PHOTO-COUPLER INTERFACE BETWEEN A TELEPHONE LINE AND ALARM CIRCUIT

摘要

PURPOSE: A photo coupler interface between an alarm circuit and a telephone line is provided to be minimized and light-weighted by adjusting the electric potential difference amplification degree of transistor and resistance. CONSTITUTION: The first photo coupler(160) receives a signal of the telephone line. The second photo coupler(170) transfers the signal of alerter to the telephone line. When the signal of the telephone line is delivered to the alerter, the electric potential difference according to the signal transformation of the telephone line uses a resistance(180) and a transistor(190) of the telephone circuit and is delivered to the first photo coupler. The delivered signal is provided to the VCC voltage and generates the electric potential difference in the second photo coupler. The electric potential difference is received to a condenser(120).