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Displacement of a movable transducer element is measured by exciting a capacitive gap (preferably differential capacitive gaps) with triangular waves of voltage to obtain a square current wave output into a zero input impedance amplifier. The square wave output is amplified and synchronously detecte

Displacement of a movable transducer element is measured by exciting a capacitive gap (preferably differential capacitive gaps) with triangular waves of voltage to obtain a square current wave output into a zero input impedance amplifier. The square wave output is amplified and synchronously detected to produce a d.c. output signal proportional to displacement. The d.c. output signal is fed back to force rebalance electrodes to electrostatically rebalance the movable transducer element. The feedback signal is a measure of the force being transduced. Initial offsets in the position of the transducer element and capacitances of the capacitive gaps are compensated by signals derived from the capacitive gap excitation waveforms.

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In a method for capacitively sensing displacement in a transducer of the type having a movable member which is displaceable relative to a support structure, the steps of: electrically exciting a capacitive gap between said movable member and an electrode fixed in position relative to said support st

In a method for capacitively sensing displacement in a transducer of the type having a movable member which is displaceable relative to a support structure, the steps of: electrically exciting a capacitive gap between said movable member and an electrode fixed in position relative to said support structure with a time varying voltage; sensing from said excited capacitive gap a time varying output signal having an amplitude variable in accordance with the variable spacing between said movable member and said fixed electrode; and amplifying the sensed time varying output signal in an amplifier having essentially zero input impedance to ground to derive an output current signal, whereby the amplitude of said output current signal is generally independent of stray input capacitance to ground of said amplifier. In a method for capacitively sensing displacement in a transducer of the type having a movable member which is displaceable relative to a support structure, the steps of: electrically exciting a capacitive gap between said movable member and an electrode fixed in position relative to said support structure with a time varying voltage which is cyclical having a period characterized in that in a first substantial portion of the period, the voltage changes with time at a generally constant first rate and has a first sign and during a second substantial portion of the period, the voltage changes with time at a generally constant rate generally equal to said first rate but of sign opposite to that of said first sign; sensing from said excited capacitive gap a time varying output signal having an amplitude variable in accordance with the variable spacing between said movable member and said fixed electrode.