charge pump 36 which produces a falling integrated output 50 that may be provided to an output amplifier 38 for example a schmidt trigger to provide a low state output signal 52 indicating that a person 39 s hand 22 is not close to the conductive plates 18 and 20 these stages tend to reject noise that is not in phase or 180 out of phase with signal 40 and to reject the momentary phase errors described above when a person 39 s hand 22 is brought near the conductive plate 18 the coupling between the conductive plate 18 and the second conductive plate 20 is weakened causing the coupling through capacitor 32 to provide the dominant signal causing the signal 40 and the output 44 u2032 of oscillator 30 to be in phase the relative coupling between the oscillators 24 and 30 along the first and second transmission paths can be used to adjust the distance at which the hand 22 triggers this in phase condition again signal 40 and the output oscillator 30 are compared by a phase detector 33 which will produce a generally high state signal 46 u2032 which is provided to the low pass filter 34 to produce signal 48 u2032 and then to the charge pump 36 to produce a rising integrated output 50 u2032 that may be provided to an output amplifier 38 to provide a high state output signal 52 u2032 indicating that a person 39 s hand 22 is close to the conductive plates 18 and 20 this signal 52 u2032 may be used to trigger a switch or a mechanical lock or.