This is a simple circuit consisting of an MPSA13 NPN Transistor and an LM393 voltage comparator IC. A handfull of resistors, two SMD LEDs and a sensitivity adjustment potentiometer complete this module. The touch sensor its self is simply the base of the MPSA13 transistor.
This is easy to hook up, there are four 0.1″ header pins. It can be plugged into a breadboard. The outputs are as follows:
- +V (3-5VDC in)
- A0 (We think this is an analog output – the voltage of the pulse may be dependent on the input voltage) – For most applications this pin should not be used.
- D0 (We think this is a digital output – the pin will pulse high when the sensor is touched)
The potentiometer adjusts the sensitivity of the module. It may take some experimentation to get it “dialed in” for your project.