This circuit was originally intended for reading movie soundtracks. The circuit is from 1967 and was found in an English publication. The sensor is semiconductor type.
This simple circuit causes an LED to flash at times whose active cycle is determined by C1 and C2....
In the figure we show the typical configuration of a shared line using a twisted pair where the...
This circuit appeared in Amateur Radio Today in an issue and was found in a 1995 issue. The...