Published in a PE Hobbyst Handbook of 1991, this sensor uses an integrated circuit that is unusual today. The circuit is based on a high frequency oscillator.
In the diagram from the November 1999 Electronics Now magazine we have the way to improve both the...
This simple circuit was found in a 2001 documentation. With each touch of CH1, a 4017 output...
With the use of a microphone and an amplifier stage, this circuit does not require connection to...