Logic and circuit with two inputs, on the intrinsic safety.

摘要

The oscillator (4) gives an output signal of the first input voltage (E1) exceeds a first threshold. A clipped amplifier (20) gives an output signal exceeding a certain value of the second input voltage (E2) exceeds a second threshold. The oscillator has a single transistor (12) whose emitter and collector are connected to two primary coils (28, 30) of a transformer (21) whose secondary (22) makes a timed circuit with a few terminal capacitor (26). The amplifier has a single transistor (32) connected through a filter to the second input and connected at the emitter and collector to transformer primary (42) whose secondary makes a resonant circuit with a low capacitor (46) which provides an ac output to a conventional low impedance gain amplifier with rectification. USE/ADVANTAGE - Railways. Low sensitivity to common mode ac input signals, allows floating mode,no need for screened enclosure.