Transcript Wheatstone Bridge A Brief Description

Wheatstone Bridge
An Overview
Orange Team
Introduction to Engineering Design
Introduction
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History
How does it work?
How is it used?
Impact of the circuit
Summary
: http://www.opamp-electronics.com/tutorials/bridge_circuits_1_08_10.htm
History
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The Wheatstone Bridge was invented in 1833
by Samuel Hunter Christie
Later named after Sir Charles Wheatstone for
his many applications of the circuit through the
1840s
The most common procedure for the bridge
remains the testing of unknown electrical
resistance
How Does it Work?
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Uses ratio of 3 known resistors
Measures fourth unknown resistance
Balanced voltage between point 1 and
battery’s negative, and between point 2 and
battery’s negative allows the measurement
: http://www.opampelectronics.com/tutorials/bridge_circuits_1_08_10.htm
How Does it Work? (cont.)
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By changing resistors to adjusting variable
resistors to balance the device, the
mathematical ratio is used to calculate the
fourth (unknown) resistance
: http://www.opampelectronics.com/tutorials/bridge_circuits_1_08_10.htm
How is it used?
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Main focus of the Wheatstone Bridge =
applications using electricity
The circuit monitors sensor devices like strain
gauges – it reads the level of the strain in the
system
The galvanometer measures whether the
gauges are balanced or not
Electrical power distributors use the
Wheatstone Bridge to locate breaks in the
power lines
Impact of the Wheatstone Bridge
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The Wheatstone Bridge is a very simple
design, although there are more complex
versions of achieving the same outcome
Can be adjusted easily
Fairly inexpensive to produce
Also indirectly measures any variable that
would change the resistance of a material
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Ex: temperature, force, pressure
Summary
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Created in 1833, popularized in 1840s
Wheatstone bridges are one of the best methods of measuring
resistance due to the basic mathematical ratio involved.
Accurate standards with sensitive enough voltmeter,
measurements of resistance within .05% can be reached.
Many calibration laboratories still use this method today.
The Wheatstone Bridge are replaceable; however, for its
simplicity and versatility the circuit is an indispensible piece of
technology
Works Cited
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Johnson, R.. "MEMS enables electrically trimmable passive resistor. " Electronic
Engineering Times 9 Mar. 2009: ABI/INFORM Trade & Industry, ProQuest. Web. 20
Sep. 2010.
Kuphaldt, Tony. "Bridge Circuits." OpAmp Electronics. Web. 19 Sept. 2010.
<www.opamp-electronics.com/tutorials/bridge_circuits_1_08_10.htm >.
"The Wheatstone Bridge: Using Bridge Circuits to Provide Signal
Conditioning."Suite101.com. Web. 20 Sept. 2010. <http://www.suite101.com/>.
"The Wheatstone Bridge. Web. 20 Sept. 2010. <http://www.play-hookey.com/>