This circuit is from a Mallory 1968’s documentation. The integrated circuit is of the time and the transistor admits equivalents.
Found in Radio Electronics from the 90s, this circuit has frequency and active cycle adjustment....
Found on 90's Popular Electronics, this circuit triggers when the microphone picks up a sound. The...
This CMOS logic-based circuit was found in the April 1974 issue of Radio Electronics magazine. The circuit...