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.
This circuit uses a common multimeter on the voltage scale. The calibration of the scale should be...
This circuit is intended to drive bistable relays and can be used as a shield for...
This circuit was found in a PE Hobbyst Handbook of 1989. It uses a black light fluorescent of the time....