Straingauge and INA125

Hi Group Im trying to hoook 2 straingauges up to INA125 Instrument Amps. Got the parts ordered, but Im having difficulties with the schematics.

I will need both Positive and negative strain from my 120 ohm straingauges. The straingauges will vary from 119.8 Ohm to 120.2 ohm so I need a Whetstonebridge. With the right gain from the INA125 this will give me a voltage( that my Arduino can read the easy part) from 0V to 5 V.

But how do I hook this up? Nomatter how look at it I will need a negative power supply also for the INA125. Am I missing something?

If anyone has a schematics it will be highly appreciated. Im Mechanical, not Electrical.


Have you looked at the examples in the datasheet for the INA125?

There are several resources out there if you search,

same problem with me,

try this one with single supply op amp. the virtual ground become 2,5v, below 2,5 become negative and upper tha 2,5v become positive

These days negative supplies are seldom used, you just set up a mid-rail virtual ground for the analog reference, usually there's a spare opamp in the package you can use to do this (you buffer a resistive divider with an opamp to provide a stiff virtual ground).

If you're working with high-grade audio you might want dual rails, but for mixed analog/digital its rare.