Using a capacitor as a sensor, this circuit was found in the 1989 Radio Electronics Experimenter magazine. The circuit must be assembled in a shielded box.
This circuit uses two light-activated SCRs or LASCRs, uncommon components today. The power depends on...
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...
Other series amplifiers such as the MC3301, MC3401 and LM2900 can be used on this circuit. We...