Use of Signal Generator for Measurement of Inductance and Capacitance Impedance Bridges

Use of Signal Generator for Measurement of Inductance and Capacitance Impedance Bridges Points : use of signal generator for measurement of inductance and capacitance impedance bridges The concept of the wheat stone (resistive) bridge can be extended to facilitate impedance measurement. Such bridge may be used to measure the values of capacitors and inductors. There are quite a variety of bridge configurations that have been developed to accomplish this, but they are all variations on the concept of the resistive bridge. One or more of the resistors in the bridge are either supplemented or replaced by inductors and capacitors. The unknown impedance is one arm of the bridge circuit and one or more of the other arms are adjusted until the mull condition is reached. Then the value of the unknown impedance can be inferred from the values of the components in the other arms in the bridge. Of course, since this is an impedance measurement, an ac (sine wave) source is used for V_s. RL and RC Circuits In most cases, resistance measurements are no problem as long as a good quality multimeter or ohmmeter is available. Measuring inductors and capacitors, however, can be difficult. Although a specialized instrument such as an impedance bridge can be used to measure inductance and capacitance, there are ways of measuring inductors and capacitors with more common Labs equipment. Step Response A resistor — capacitor (RC) circuit and a resistor — inductor (RL) circuit are shown in the fig.

These two circuits have some very similar properties that can be used to determine the value of either the inductor or capacitor in the circuit. If the input (V_s of the circuit is abruptly stepped from 0 Volts to some positive value, the output, voltage (V_o) rises in a exponential manner, as shown in fig.