We found this circuit in the December 1998 issue of Electronics Now magazine. RF transistors such as the BF494 or BF495 can be used. The circuit works at lower frequencies.
This circuit is from a March 1978 Radio Electronics magazine article that showed how to build it....
This circuit was obtained from an article in Radio Electronics magazine in October 1966. It...
In the figure we have a bistable circuit that activates LEDs from touch rings and turns off data...