Any high-gain Darlington transistor can be used on this touch circuit. The load can be formed by LEDs and the power supply isolated from the power grid.
This circuit was found in 1968 General Electric documentation. The circuit uses components from the era...
This circuit was obtained from an English magazine from 1979, but can be easily assembled...
We found this circuit in an American brochure from the 90s. In it we have the way to implement a 4-input...