Download lecture 7 - FTP Gunadarma

PERTEMAUAN 10 – 11
AC Bridges dan APLIKASINYA
Maxwell Bridge
•
•
The Maxwell bridge measures an
unknown inductance in terms of a
known capacitance.
The maxwell bridge is limited to
the measurement of medium-Q
coils (1<Q<10).
Rx 
R2 R3
R1
Lx  R2 R3 C1
Hay Bridge
•
•
•
•
The Hay circuit is more convenient
for measuring high-Q coils
Hay bridge for inductance
measurements ---------------------
Impedance triangles illustrate
inductive and capacitive phase
angles --------------------------------
for Q>10 :
L x  R2 R3 C
Schering Bridge
•
•
The Schering bridge, one of the
most important bridges, is used
extensively for the measurement
of capacitors.
Schering bridge for measurement
of capacitance --------------------
R x  R2
C1
C3
C x  C3
•
R1
R2
Dissipation factor :
D  R1C1
Unbalance Conditions
•
Bridge balancing problem :
– (a) unbalanced condition
– (b) bridge balance is restored by
adding a resistor to arm 1
(maxwell configuration)
– (c) Alternative method of restoring
bridge balance, by adding a
capacitor to arm 3
Wien Bridge
•
Applications :
– Frequency measureent
– Notch filter
– Frequency-determining element
•
Frequency measurement with the
Wien bridge -----------------------
f 
1
2RC
Wagner Ground Connection
• The wagner ground connection
eliminates the effect of stray
capacitances across the
detector
Universal Impedance Bridge
• Universal impedance bridge
• Bridge configurations of
the universal impedance
bridge