jembatan wheatstone

1. Bridge Circuits
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2. Bridge Circuits
g
Wheatstone Bridge: The primary application of this
g p y pp
bridge in signal conditioning is to convert variations of
resistance into variation of voltage
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3. Wheatstone Bridge
g
VO will equal zero. In this situation, the bridge is said to be
BALANCED. Any change in any resistive element will result in an
UNBALANCED condition, hence VO will be non-zero.
,
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4. Wheatstone Bridge
g
If we replace R3 with an active strain gauge, RG, which
will vary b ∆R when pressure i applied (th arrow
ill by h is li d (the
through the resistor shows that it has a variable value),
then
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5. Example 1:
p
The resistors in a bridge are given by
R1=R2=R3=120Ω and R4=121Ω. If the
supply is 10V Find the voltage offset?
10V.
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6. AC Bridges
g
AC bridges are used mainly to detect changes
in inductance and/or capacitance
At balance condition
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7. Example 2:
p
An ac bridge is in balance with the
following constants: arm AB, R = 200 Ω
in series with L = 15 9 mH ; arm BC R =
15.9 BC,
300 Ω in series with C = 0.265 µF; arm
CD,unknown;
CD unknown; arm DA = 450 Ω The
DA, Ω.
oscillator frequency is 1 kHz. Find the
constants of arm CDCD.
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8. Comparison Bridge: Capacitance
p g p
Measure an unknown capacitance by comparing it with a
p y p g
Known capacitance.
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9. Comparison Bridge: Inductance
p g
Measure an unknown inductance by comparing it with a
y p g
Known inductance.
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10. Maxwell Bridge
g
Measure an unknown inductance in terms of a
known capacitance
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