problem with ADC1230REF AND THREE WIRE LOAD CELLS

Bilal Ahmad

hi,

i my doing work on digital weight machine.in this i m facing problem in connecting four load cells to 20 bit adc (ADC1230REF

).......
i m not getting any idea of load cell.
bec its resistance does not varies as i inserted force on it..
kindly help me out ....

i have attached the images of load cell(3 wires red,black,white) and 20 bit ADC board.

kindly tell me how to use 3 wire load cell ............... in order to make weight machine .....
do i need to make any type of bridge...??????

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3 Wire Load Cell-26082009-001-.jpg.jpg
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3 Wire Load Cell-26082009-002-.jpg.jpg
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3 Wire Load Cell-26082009-003-.jpg.jpg
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over 16 years ago

0 Rick Downs - WEBENCH Design Center over 16 years ago

TI__Expert 5515 points

Do you have any specifications on the load cell you're using? Do you know where (electrically) on the sensor the wires are attached? Chances are this is actually a three-wire strain gauge, which could be used to make up one or two legs of a bridge. See http://www.vishay.com/docs/11092/tt612.pdf.

0 Bilal Ahmad over 16 years ago in reply to Rick Downs - WEBENCH Design Center

Prodigy 80 points

i hav attached the file of load cell

kindly consider it.....

small load cell for body scale.pdf

0 Rick Downs - WEBENCH Design Center over 16 years ago in reply to Bilal Ahmad

TI__Expert 5515 points

Unfortunately, there's no schematic representation, and I couldn't find one in a web search. What we do know is that it is a 1000ohm cell, so if you use an ohmmeter across the wires, what resistances do you measure? I suspect that one combination will give you 1000ohms, and other combinations will give you around 500 ohms each. Something like this:

This would be a half-bridge, so you'd need two other resistors to make it a full bridge.

Hope that helps.

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problem with ADC1230REF AND THREE WIRE LOAD CELLS