Hays Bridge

Theory

In Hay’s bridge, the capacitor is connected in series with the resistance, and the voltage drop across the capacitance and resistance are varied.

circuit
Fig. 1 Hay's Bridge

Let \( L \) be the inductance whose value is to be determined, \( R_1 \), \( R_2 \), and \( R_3 \) be the variable resistance, \( C \) be the variable capacitance.

At the balance condition,

\( (R_1 + j\omega L_1) \times (R_4 - j\omega C_4) = R_2 \times R_3 \)

For inductor with high Quality Factor,

\( L = R_2 \times R_3 \times C \)

This provides a relationship for determining the unknown inductance \( L_2 \) using the given method.