We found this circuit in the October 1996 Electronics Now magazine. The circuit uses LDRs as sensors and drives relays. The relays must have voltages according to the power supply.
This is a basic version of the Tesla coil that does not use semiconductor devices, found in an old...
This circuit was found in a National Semiconductor manual from the 1980s. The integrated circuits used...
This circuit uses an optical coupler called Raystor created by Raytheon in the 1960s. The circuit...