Found in Radio Electronics from the 90s, this siren finds many variations on this site. The transistor must be equipped with a heat radiator.
This sensitive circuit was found in the August 1971 issue of Radio Electronics magazine. The SCR...
Suggested by General Electric, this circuit with triac is able to reverse the rotation of a motor...
This circuit applies to an old dial phone by detecting light pulses in the dial. The circuit is...