Monroe-electronics Electrostatic Voltmeter - Isoprobe® - model 279L Instrukcja Użytkownika Pobierz pdf (Strona 12)

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If, however there exist voltage sources in the vicinity of the sensitive electrode which are independent of the

unknown to be measured, the offsets produced will detrimentally affect the spacing independence. Such voltage

sources include contact potential differences among the internal probes parts, small specks of charged dust

particles, etc.

The null balance circuitry is provided to neutralize such offsets by applying a voltage directly to the sensitive

electrode.

C. Zero: (ZERO 2)

The instrument's zero control is a voltage source connected in the metering circuitry. It is used to overcome offsets

produced by voltage sources external to the probe.

D. Gain:

The instrument functions as a closed loop unity gain voltage follower. Its open loop gain from probe to integrator is

determined by the gain of various amplifiers. The exact gain required for optimum transient responses during a

specific measurement is determined by the probe-to-surface spacing used. In order to accommodate

measurements at various probe-to-surface separations, a front panel gain control is provided which controls the

gain of the signal amplifier.

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Monroe-electronics Electrostatic Voltmeter - Isoprobe® - model 279L Instrukcja Użytkownika Strona 12