Monitoring simultaneous arrival of DC or AC pulse trains - using energy of one signal sequence to actuate switching element only if other signal appears at least approximately at same time

摘要

A monitoring circuit has two inputs (IN1, IN2) for either two a.c. signals, or two pulsed d.c. signals. One signal (IN1) is received by a diode (D2) and capacitor (C3) such that the voltage applied as a control input to a gating stage (5) increases in amplitude as the pulses are received. When a set input level is exceeded the element responds to gate the other signal (IN2) through to the output. The circuit is based on an amplifier stage. USE/ADVANTAGE - Fail-safe monitoring for railway signalling.