This circuit fires with the noise captured by the touch of a sensor. Signal shapes are given next to the diagram. The circuit is from the 80s, using components from that time.
This proximity relay circuit was found in the July 1990 Radio Electronics magazine. The supply...
This circuit is from an old operational amplifiers manual. However, the setting applies to modern...
Using an operational amplifier, the figure shows how to convert the waveform to low frequency...