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 was found in a 1980s telecommunications publication. The circuit uses a diode bridge to...
This circuit is from an English magazine from 1980, but it can be easily assembled with more...
The indicated circuit is an intermittent one in which we use two 555 integrated ones, one as a low...