I'm working on a project where I should send an overload signal if the strain is bigger than 40 ppm.

So far I found this answer:

Strategy to balance a Wheatstone bridge for strain measurement

The wheatstone bridge consists 2x 120 ohm, GF 2 strain gauge and two 120 ohm 0.1% resistor.

Using the answer above I'd make it so that at 40 ppm the in-amp's output would drive a JFET.

I think that a ina-128 would be a good choice, but the power source is x piece 1,5 V battery so I'd need 4.

Is it a good choice, can you recommend a better for this application?


1 Answer 1


Shopping questions area off-topic, but in general terms I would definitely go for one of the newer type of "zero drift" instrumentation amplifier that has a maximum supply voltage of ~5V or less.

Go to either a manufacturer (TI, AD, etc.) or to a distributor such as Digikey and do a parametric search, then compare datasheets.

A quick search yields, for example, the AD8237 which sports a 115uA current drain at 1.8 to 5.5V and 75uV maximum Vos.

  • \$\begingroup\$ Okay, so single supply solutions exist (I'm new to this), "zero drift" means those with 5 ppm gain drift? Nevermind I found titles with zero drift. \$\endgroup\$
    – Hegedus.Cs
    Jul 19, 2018 at 23:16
  • \$\begingroup\$ 'Zero drift' means they have an internal topology that uses switching techniques to reduce Vos and TCVos. \$\endgroup\$ Jul 19, 2018 at 23:19
  • \$\begingroup\$ Just t make it clear, I just connect the two points of the wheatstone bridge to in+ and in-, Vout is output, I connect everything else as shown at Figure 72. Using Voltage Divider to Set Reference Voltage Vs- is the negative, Vs+ is the positive end of the battery? \$\endgroup\$
    – Hegedus.Cs
    Jul 19, 2018 at 23:35
  • \$\begingroup\$ Other than that where or how can I ask questions like this? Before you mentioned I didn't even know about zero drift solutions, I only knew the offset voltage, that it'd batteries and that what is it used for. I found ina-128 at TI just I wasn't sure I know all important properties of an in-amp for this application. \$\endgroup\$
    – Hegedus.Cs
    Jul 19, 2018 at 23:39
  • \$\begingroup\$ I don't know what circuit you have in mind. Better to provide the whole schematic, preferably in another question. If it's just a comparator with no hysteresis you don't even need an in-amp, a zero-drift RRIO op-amp will do. 0.1% resistors are 100ppm so you will need to trim the circuit. \$\endgroup\$ Jul 19, 2018 at 23:39

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.