This circuit for the power grid was found in the June 1969 Radio Electronics magazine. The SCR and diodes are rated according to the power of the controlled load.
We found this circuit in factory documentation from the 70s. The operational amplifier is from...
This circuit for powering TTL and even modern microcontrollers is from February 1987, Radio...
We found this touch switch in a Popular Electronics from the 80's. The circuit can also be...