Abstract: A meter circuit for measuring the effective series resistance (ESR) and Q-Factor of a capacitive device has an operational amplifier with an input to which a source of AC input voltage is applied. A feedback circuit is connected between output and input of the amplifier. A series network is connected between the feedback circuit and ground. This network has an inductor of known Q-Factor in series with a capacitive device whose Q-factor is to be determined. Voltmeters measure the applied input voltage and output voltage of the amplifier. Where the series resistances of the inductor and capacitive device at resonance frequency have a low total magnitude, the meter circuit can be modified by inserting a wideband transformer, having very low output impedance, in the feedback circuit in series with an adjustable gain operational amplifier.