This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit uses a unusual optocoupler that can be replaced with an equivalent one.
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...