Opto-electronic switch for vehicle ignition - has gallium arsenide LED illuminating phototransistor with saturation limiting Schottky diode across base-collector path

摘要

The opto electric switch consists of a GaAs LED illuminating a phototransistor switch via a shutter. A Schottky diode (SD) is connected across the phototransistor's base/collector junction to prevent it from oversaturating due to receiving too much radiation. The diode is poled so that it carries current from the base to the collector. The switch is for use in eg a vehicle's electronic ignition circuit, responding quickly even in the presence of over-intense radiation.