This digital circuit is from a Radio Electronics magazine from December 1991. It does not use a microcontroller, but rather discrete digital circuits of the time.
From a 90s Popular Electronics, this circuit emits pulsating signals for different types of...
Found in a Popular Electronics from the 90's, this circuit converts a 40 V symmetrical source to a 5...
This circuit generates frequencies determined by R3 and C1. We found it in the Radio Electronics magazine...