Unlike the CIR4620 circuit, the circuit shown in the figure operates by capacitance. This means that approaching the X1 sensor hand causes the change in capacitance in the circuit to trigger the trip, with the production of a high logic level at its output. The circuit is formed by an oscillator that operates at a frequency of a few hundred kilohertz, built around one of the 4093 ports. The signal from this circuit is detected and applied to the CA3140 operational amplifier. The level of signal applied depends on the possible existence of an external capacitance applied via C2. This capacitance comes precisely from the approach of any object of the sensor. The adjustment of the trigger point is made in the trimpot P1. The diodes are for general use and the signal at the output can be used to trigger a power step, exactly as suggested in the previous circuit. The power supply does not have to be symmetrical, but it must have excellent filtration.
