Bridge circuit for interrogation of the status of a switch

摘要

A microcontroller is connected to an amplifier (24) and an amplifier (30) operating inversely. The amplifiers have inputs (32,34) which receive respective different reference voltages. The outputs of the amplifiers are connected to respective terminals (54,56) for the switch (58). Each amplifier is provided with an opto-coupler (48,52) with a photodiode (42,44) and a phototransistor (46,50). The respective photodiode is connected to the output of the associated amplifier, and the phototransistor to the input of the associated amplifier.