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.
This circuit was originally designed for medical applications and biological experiments. The...
This circuit for a frequency of 40 kHz was found in an old Electronic Design. There were no...
The simple touch of the fingers on a sensor causes this circuit to drive a motor that goes into...