This tone recognizer circuit that relies on R5 and C1 was found in the December 1994 issue of Electronics Now. The circuit operates on voltages from 6 to 12 V typically.
This circuit is from old documentation, but can be easily assembled as components are still...
We found this circuit in the September 1994 issue of Electronics Now magazine. The circuit uses...
We have dozens of similar projects in articles and circuits on this site. This is from Radio...