This plug-in control was found in General Electric documentation from the 1970s. The SCR can be the TIC106 mounted on a heatsink. The circuit can be changed to the 220 V network.
This is yet another version of the light-controlled oscillator that can be found on this website. This...
Originally created to feed the filaments of a 12AX7 as an audio preamplifier to eliminate the...
The incidence of light in the LDR causes this circuit to start operating, emitting a sound whose...