This circuit is from a Popular Electronics from the 90s. It uses an opto-coupler with SCR directly controlling a 20 mA current load.
This small blocking oscillator for approximately 1000 Hz was found in an American documentation from the...
This isolated solid state relay can function as a shield directly controlling 10 A loads. The...
This circuit was found in a 1974 publication. It converts the applied voltage into pulses of...