This very simple circuit uses a phototransistor and a very sensitive relay (reed type) being used over short distances with a lens system. The circuit is from a 1967 Japanese publication.
In the figure we have the way to compensate an operational amplifier. The circuit is valid for...
circuit is used to increase the sensivity of a relay. A 50 to 100 mA relay can be triggered with...
a This very low voltage regulator supports input voltages from 1.7 V to 5.5 V and is suitable for IoT...