Measurement of Capacitance by De Sauty's (Modified) Bridge

  Procedure:

  1. Set the voltage (V=3V) and Frequency (50Hz) and set the unknown capacitance value from 'Set Capacitor Value' tab by clicking on 'Set' button.

  2. Then switch on the supply to get millivoltmeter deflection.

  3. Now vary the values of R1, R2, R3, R4 and C1 from the control box below or directly put the values in the boxes of respective elements.

  4. Observe the millivoltmeter pointer to achieve "NULL".

  5. If "NULL" is achieved, switch to 'Measure Capacitor Value' tab and click on 'Simulate'. Observe calculated values of unknown capacitance (C2) and unknown internal resistance (r2) of the capacitor. Also observe the Dissipation factor of the unknown capacitor, which is defined as `w * C * r`. where, `w=2 * π * f`.

    6. N.B.:-
    Range of C1=100`pF` to 11.111`uF` (in steps of 100 `pF`).
    Range of R1, R2, R3 and R4= `1  Ω` to `11111110  Ω`  (in steps of 1 `Ω`)

Tutorials Point

`Ω`

Voltage:

Frequency:

V

Hz

`F`

`Ω`

`Ω`

`F`

`mV`

5`Ω`

  • Set the actual values of C2: (r2 value is fixed at 5 Ω)
      Enter the C2 value and click on the set button.
       C2 (in uF): 
    0.001 uF    0.1 F

    C2=

    `uF`

  • The current voltmeter reading is:   mv. Now simulate to get:
         Capacitor value (in uF):
    Resistance value (in Ω):
    Dissipation Factor:
CONTROLS
   R1 : 1 Ohm     11.11111 MΩ
   R4 : 1 Ohm     11.11111 MΩ
   R3 : 1 Ohm     11.11111 MΩ
   R2 : 1 Ohm     11.11111 MΩ
   C1 : 0.0001 nF     100F