This circuit was found in an English documentation from the 90s. It uses a PLL CMOS 4046 and is powered by a 9 V battery. The sensors are two electrodes that must be held by the person.
This very simple circuit uses a phototransistor and a very sensitive relay (reed type) being used...
We found this circuit in Radio Electronics magazine from January 1958. It uses a neon lamp as the...
The integrated circuits in this application are not very common today. One consists of an A / D...