This circuit with SCR is from a Radio Electronics magazine from September 1965. It is a commercial control from Heathkit for controlling universal motors.
Suggested by General Electric in 1965 documentation, this circuit controls the current at a load...
Found in Popular Electronics from the 1980s, this circuit uses two operational amplifiers from...
We found this circuit in a Hands-on Electronics from 1985. The circuit is based on common...