This circuit uses two relays that switch when the voltage exceeds the value given by zener D2. The circuit is from a Radio Electronics magazine from April 1975.
Vishay's VCNL4200 integrated circuit consists of a fully integrated proximity detector containing...
This circuit samples the current in a load and in case of excessive value it activates a...
The frequency of this oscillator depends on the crystal used and the transistors. The circuit was...