This circuit is for old telephones with analog lines. It was found in the May 1988 Radio Electronics magazine. The circuit is powered by the line signal voltaje.
A tap on sensor X1 of the circuit shown in the figure causes the flip-flop formed by the 4 NAND...
September 2016 - It can be obtained from Mouser Electronics the FAN602 integrated circuit...
This traditional 555 touch bistable configuration has already been explored in projects on this...