This circuit is from a 1967 General Electric SCR manual. The capacitors are polyester and the inductor must have current according to the controlled load.
This circuit was obtained from the Radio Electronics Experimenter magazine in a special edition of 1990....
This circuit was found in a 1980s documentation. It triggers a relay when liquid from a reservoir...
We found this peak audio indicator in a 1980 publication. The M1 indicator can be 200 uA with the...