Fail-safe photoamplifier circuit with a safety light curtain system

摘要

A modulated photoamplifier precludes false output signals and oscillations in the event of component failure. The photoamplifier converts modulated electromagnetic energy into voltage pulses. A phototransistor receives the modulated electromagnetic energy and generates corresponding current pulses. A differential amplifier with negative feedback receives the current pulses and produces the corresponding amplified voltage pulses. A capacitor within the feedback network produces optimum gain at the frequency of the modulated electromagnetic energy. A failure of any component within the photoamplifier removes its ability to generate voltage pulses. Therefore, the photoamplifier precludes false output signals and fails to a safe condition in response to the component failure.