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Wheatstone bridge/multiSIM help

Arouse1973

Adam
Dec 18, 2013
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Your DMM will not show the correct reading with external power connected to it. Resistance measurements should be done without power connected.

I can't see anything wrong with your circuit as far as your results go. You have a gain of about 146 so this would give you the results you have. You need to change your gain if you want a higher output for a given input. It's not clear to me as you say 0-5 Volts output for 1mV input. You can only get this if you change your gain of the amp.

Adam
 

Chris13

Sep 16, 2014
26
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Sep 16, 2014
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26
Hi,

Thanks Adam - such an obvious mistake when it is pointed out!

I have my gain resistor setup now so that at 20mV from my bridge I get 5V output.

I notice when my bridge output is 0mV (or as close as possible, 4.749μV) my output is 903mV. Can anyone suggest how I get this to zero?

Thanks,
 

Arouse1973

Adam
Dec 18, 2013
5,178
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Hi Chris
Also just noticed you are using a single supply, just check your not violating the input common mode range for the device and that the outputs can drive to 0V which I doubt. You would be better off using a split +/- 5V supply if you can.
Adam
 

Arouse1973

Adam
Dec 18, 2013
5,178
Joined
Dec 18, 2013
Messages
5,178
Hi,

Thanks Adam - such an obvious mistake when it is pointed out!

I have my gain resistor setup now so that at 20mV from my bridge I get 5V output.

I notice when my bridge output is 0mV (or as close as possible, 4.749μV) my output is 903mV. Can anyone suggest how I get this to zero?

Thanks,

Split supply as mentioned above.
Adam
 

Chris13

Sep 16, 2014
26
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Sep 16, 2014
Messages
26
I intend to make the amp battery powered - would this be possible?
 

Arouse1973

Adam
Dec 18, 2013
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Yes, two batteries would be required in series and connect the common point of the circuit to the centre where the two batteries meet. The other connections go to the power supply pins of the INAMP.
Adam
 
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