This circuit triggers a relay when a light beam that hits the phototransistor is cut off. The circuit is from Electronics Now and the supply voltage depends on the relay voltage.
This circuit was found in a Radio Electronics Constructor, English magazine from April 1976; The...
This circuit was found in General Electric documentation from 1966. The circuit is suitable for any...
This 48 V circuit with a capacity of up to 105 V was found in a 2005 Linear Technology manual. The...