Wien bridge

The Wien bridge is a type of bridge circuit that was developed by Max Wien in 1891. The bridge comprises four resistors and two capacitors.

Bridge circuits were a common way of measuring component values by comparing them to known values. Often an unknown component would be put in one arm of a bridge, and then the bridge would be nulled by adjusting the other arms or changing the frequency of the voltage source. See, for example, the Wheatstone bridge.