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.
The coil of this receiver consists of 100 turns of wire 38 to 30 in a ferrite rod and the...
This filtered High Side sensor circuit was found in a 2005 Linear Technology application manual....
This frequency modulated light transmitter is from a 1990s documentation. The circuit may use...