Found in a 1980s documentation, this circuit uses transistors from that time. Modern equivalents can be used. The alarm is a piezoelectric buzzer with na included oscillator.
The field effect transistors have characteristics that allow the realization of excellent...
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...
This circuit was obtained in a 80s American documentation for radio amateurs. The circuit produces a...