This sensitive touch potentiometer is based on IC1 (CA3130), one operational amplifier with a high input impedance.
When the finger touches Se1 sensor, C2 (MKT type capacitor) is charged through the resistance of skin, and this will cause the linear dropdown to zero of the IC1 output voltage. When we touch Se2 sensor the opposite occurs. The output voltage of IC1 with grow in a linear way until it reacheas the value of the power supply voltage.
If you get the finger out of the touch sensor the voltage value at the IC1’s output will be maintained by the charge stored in C2. Yet, this voltage will drop with about 2%/1 hour.
This touch potentiometer circuit has different applications and can be user anywhere is needed a potentiometer wich can be controlled with variable voltage.
If you want to use normal commutators or buttons instead of the touch sensors then place a 1M resistor in serial as shown in the schematic.