An admittance meter having an electrical alternating signal source, a diode ring operated as a synchronous rectifier with at least four diodes connected in series and in the same direction in succession, a measuring sensor, and an evaluation unit. The diode ring is subjected to an alternating signal via first second feed points, which are each connected via two series-connected diodes. The measuring sensor is connected to the first feed point, and the evaluation unit is connected to a first or a second measurement point of the diode ring. The first and second measurement points are each connected via one diode to the first and second feed points, respectively.