Before the advent of digital electronic voltmeters, accurate measurement of a voltage or impedance was achieved by applying the compensation method. The unknown quantity is compared with an adjustable known one of the same kind. The known quantity is changed until the difference is zero, which is detected by a sensitive null-indicator. In equilibrium, the unknown quantity is equal to the known one. In this way, voltages, currents and impedances can be accurately measured.
Instruments for voltage and current are called compensators. They comprise an accurate voltage source (reference cell) and a resistance network with adjustable topology, providing a range of attenuation factors.
The instrument for measuring a resistance (impedance) is called a bridge. It contains one or more reference resistors (impedances) and a stepwise adjustable resistance, called a resistance decade box.
Examples of compensators, bridges, reference voltage sources, reference resistors and decade banks are all displayed in this cabinet.
More types are stored in the depository of the Historical Collection of the Ampère Foundation.
Locatie: RaM Carre3
Beheerder: P.P.L.Regtien