KSV SPOT
KSV SPOT Manual
Rev. 1.0
6
4. KSV SPOT principle of measurement
The block diagram of the measuring circuit of KSV SPOT meter is shown below.
The upper electrode (vibrating plate) of the capacitor is set to vibrate with a frequency
between 100-180 Hz. The upper electrode of the capacitor is placed a couple of mm from the
test surface (solid or air/liquid interface depending on which type of measurement is
performed). As the upper electrode vibrates, the capacitance between the electrode and the
test surface changes. This change in capacitance induces an AC current to the circuit due to
the fact that there exists a potential difference between the electrode and the test surface. This
current is amplified and analyzed by together with the signal from the oscillator. Thereafter
the control electronics adjusts the DC current controlling the potential of the feedback
capacitor until the compensating voltage equals the surface potential and no currents occur.
