With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of the 555. The circuit was found in the November 1989 Radio Electronics magazine.
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...