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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?

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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.

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  • \$\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

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