ac dc bridges

The AC and DC bridge both are used for measuring the unknown parameter of the circuit. The AC bridge measures the unknown impedance of the circuit. The DC bridge measures the unknown resistance of the circuit.

1. PRESENTED BY
CHIKKU JOSE
Department of Electronics Engineering
[email protected]

13. ACbridge
DCbridge

23. Wheatstone bridge

32. Self-Inductance
Maxwell’s Bridge
◦Maxwell inductance bridge
◦Maxwell inductance capacitance
bridge
Hay’s Bridge
Andersonbridge
Owen’s Bridge
Capacitance
De SaultyBridge
Schering’sbridge
MutualInductance
Carey foster;
Heydweiller bridge
Frequency
Wien’sBridge

33. Four arm bridge –AC bridge
Inductance and capacitance can be measured
Galvanometer is replaced by Vibration Galvanometer

34. Maxwell inductancebridge
Used to measureinductance
◦By comparison either with a standard variable selfinductance.
Maxwell inductance capacitancebridge
Used to measureinductance
◦By comparison either with a standard variablecapacitance.

35. Advantages
1)The balance equation is independent of frequency.
2)The two balance equations are independent ; if we choose R4 and
C4 as variable elements.
3)The bridge yields simple expression for unknown L1 and R1 in
terms of known elements.
4)It is useful for measurement of wide range of inductance at power
and audio frequencies.

36. Disadvantages
Variable standard capacitor will be expensive
It cannot be used for measurement of high Q values, it is limited to
measure low Q value (1<Q<10)