This circuit was found in the February 1985 issue of Radio Electronics magazine. It is based on an AY-3-1350 melody generator that was common at the time. It is suitable for analog lines only.
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...