# Is it posisble to get microstrains from the HX711 module?

Hi!

I was wondering if it is possible to get micro-strains from my HX711 module when I compress my load cell.

I am trying to get deformation length of my load cell when it is compressed.

When you multiplay micro-strins with the length of your strain gauge you get deformation length.

Has anyone done this before?

Dunno , but if you know the characteristic of the strain gauge , then with some maths you can calculate the output voltage from the bridge for a given deflection - but it would need calibrating because if the 711 amplifier tolerance ( measure input and output voltage?)

You could calibrate by bending beam a known amount by using a known deflection - measure using a dial gauge . The Hx711 examples effectively work out weight , by setting a known weight > giving a deflection> creating a voltage > calibrated as “weight”

paco09:
I am trying to get deformation length of my load cell when it is compressed.

What load cell, and why do you want to know its "deformation length"?

hammy:
Dunno , but if you know the characteristic of the strain gauge , then with some maths you can calculate the output voltage from the bridge for a given deflection - but it would need calibrating because if the 711 amplifier tolerance ( measure input and output voltage?)

You could calibrate by bending beam a known amount by using a known deflection - measure using a dial gauge . The Hx711 examples effectively work out weight , by setting a known weight > giving a deflection> creating a voltage > calibrated as “weight”

Thanks Hammy, I was thinking the same, about doing some maths. I was just expecting an easier solution hahaha like a library or something like that. Anyway... let's do it.

Thank you!

DaveEvans:
What load cell, and why do you want to know its "deformation length"?

Because I am designing a device that goes underground to measure mechanical properties of soils.

Just by now I am using a load cell, but I'll be using a cantilever with strain gauges to measure external forces.

That's the idea...

If you know the strain gauge factor, the gauge location(s) and arrangement within the load cell, (and perhaps Poisson's Ratio of the load cell material may be needed), then you can calculate the strain at the gauge location from the gauge output voltage.

That's a strain gauge's raison d'etre.

However, whether that strain can be used to calculate the overall deformation of the load cell by simply multiplying the strain by the cell length depends on whether the strain is uniform throughout the load cell. That's unlikely unless it's simply a straight axially-loaded bar with uniform section throughout its length.

Your project sounds interesting. What mechanical properties of soils are you attempting to measure, and how do you intend to do that with an underground gauged cantilever?