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 old documentation. The components can be replaced by modern ones. The...
This transistor circuit consists of a well-known bass and treble control configuration. The...
With the circuit shown, you can have a fast response with a Darlington configuration. The circuit is...