This circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit is based on a 741 that activates a buzzer with oscillator. R5 adjusts the sensitivity.
Found in an old neon lamp applications manual, this circuit directly triggers an SCR. R and C...
This 20 MHz bandwidth circuit was suggested by the National Semiconductor in 1970 documentation. Modern...
This circuit cuts out ads between songs, based on the fact that the speech signal has small...