This circuit was published in the July 1993 issue of Electronics Now magazine. It uses a sensor from the time and triggers a buzzer with a Sonalert-type oscillator.
Found in a 1990s Motorola documentation, this high voltage circuit uses a PUT that is not a common...
This circuit was found in a Popular Electronics from the 90s. The frequency range generated...
This circuit was found in a 1963 magazine, but can still be easily assembled with some current...