This circuit is from old documentation, using a component that cannot be found easily today. The indicator is a galvanometer, and the input voltage is in the order of 1 V.
This circuit is from the 1977 RCA Linear Integrated Circuits Manual. The circuit has a...
This circuit was found in 1980's Radio Electronics. The circuit produces a 1500 Hz modulate 35 kHz....
The maximum power of the controlled load depends on the triac used. The circuit is from a Radio...