Electrical Engineering ⇒ Topic : Measurement of Frequency (Wiens Bridge)

MEASUREMENT OF FREQUENCY (WIEN'S BRIDGE)

Figure (a) shows the schematic diagram of Wien's bridge to measure the frequency. This bridge is primarily known as the frequency measurement bridge.

At balance, it can be written as:

                                                       figure (a)

         .......... (1)

Equating the real and imaginary parts of both sides of Eq. (1), it can be expressed as:

                                                            ............. (2) 

                                                         .............. (3)

                                                  .............. (4)

If R₁ = R₂ = R and C_l = C₂ = C, Eqs. (2) and (4) reduces to

                                                                          ............... (5)

                                                                        .............. (6)

It is possible to measure frequency in the range 100 Hz to 100 kHz with an accuracy of 0.1% to 0.5%.