This powerful sound emitter used in defense to intimidate people was found in a 90s Popular Electronics. The circuit produces a strong modulated tone of 3 kHz. The modulation is 10 Hz.
Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It...
This circuit was found in documentation from the 1980s requiring a variable power supply from 0 to...
This car alarm was found in an American '80s documentation. The circuit automatically activates...