This circuit is from a March 1978 Radio Electronics magazine article that showed how to build it. The circuit is TTL based and is powered. The components used can still be found.
This circuit uses two light-activated SCRs or LASCRs, uncommon components today. The power depends on...
This type of configuration can be seen elsewhere in this section. This is from a 1965 General...
Crystals from 100 kHz to 1 MHz can be used in this 1957 Raytheon circuit. 4 can have values...