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 is a classic FM amplifier IF amplification stage configuration. The circuit is from a 1980s...
This staircase generator was found in the July 1991 issue of Radio Electronics magazine. Its...
This 80's circuitry decodes stereo signals used in analog TV at the time. The circuit can be used...