Wheatstone Bridge An Overview

1
Wheatstone BridgeAn Overview

• Orange Team
• Introduction to Engineering Design

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Introduction

• History
• How does it work?
• How is it used?
• Impact of the circuit
• Summary

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e_circuits_1_08_10.htm
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History

• 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

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How Does it Work?

• Uses ratio of 3 known resistors
• Measures fourth unknown resistance
• Balanced voltage between point 1 and batterys
  negative, and between point 2 and batterys
  negative allows the measurement

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How Does it Work? (cont.)

• By changing resistors to adjusting variable
  resistors to balance the device, the mathematical
  ratio is used to calculate the fourth (unknown)
  resistance

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e_circuits_1_08_10.htm
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How is it used?

• 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

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Impact of the Wheatstone Bridge

• 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
• Ex temperature, force, pressure

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Summary

• 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

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Works Cited

• 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.
  ltwww.opamp-electronics.com/tutorials/bridge_circui
  ts_1_08_10.htm gt.
• "The Wheatstone Bridge Using Bridge Circuits to
  Provide Signal Conditioning."Suite101.com. Web.
  20 Sept. 2010. lthttp//www.suite101.com/gt.
• "The Wheatstone Bridge. Web. 20 Sept. 2010.
  lthttp//www.play-hookey.com/gt