This circuit has the function of automating some type of equipment when a powerful transmitter is activated nearby. The circuit was found in a 1967 documentation.
This circuit can also use other series operational amplifiers such as MC33172, MC33174, MC35171,...
Found in Popular Electronics from the 90s, this circuit mutes a scanner's speaker in the absence of a...
This circuit was found in General Electric documentation from 1965. The transistors are from that...