Wheatstone Bridge 2

A Wheatstone bridge is a combination of four resistors connected in a ring. This results in four junctions, which I will call 1, 2, 3 and 4. Power is applied across junctions 1 an 3. Voltage is measured across junctions 2 and 4. If all resistors are equal the voltage will be zero. if one resistor has a slightly different resistance, then a voltage will be produced across junctions 2 and 4. This voltage will always be a fixed ratio to the applied voltage. A special circuit is used to measure this ratio. This makes the circuit independent of the applied voltage.

Typically one resistor is replaced by a strain gauge. The ratio is then a measure of the amount of strain applied.

Hope this helps.

see:
It's primary utility is to measure a change in resistance, instead of the absolute resistance of the strain gage. This allows one to minimize the dynamic range of the measurement, thereby increasing resolution/sensitivity

TTFN (ta ta for now)
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Thanks a lot very helpful, any chance anyone knows any books or websites I could use to read about the applications of the Wheatstone bridge in the robotic or mechanical sector. I am finding it hard to find any information on this specifically thanks.

I'd look around the Micro-Measurements web site.