Setup a 3 wire strain gauge

Other Hardware General Electronics
1

All,

I am trying to set up a single 50kg 3 wire strain gauge (from
Amazon) to a HX711 (also from Amazon). I'd like to only use one of these gauges as I do not require the extra output. I have tried to build the other side of the bridge using 2 1K ohm resistors. You can see my attempt from either the attached Fritzing diagram or schemata. I have also attached a picture of how I have physically wired everything.

Currently I am not getting any reading from this setup and I am trying to understand what is either incomplete or wrong. Any help would be appreciated.

I am very new to all of this.

Thanks in advance.

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loadSchematic.PNG
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2

Measure the voltage on E+ , using E- as ground reference.
It should be ~4.3volt.

Measure the voltage on A+
It should be ~2.15volt (half of E+).
If not, the load cell is connected wrong.
(try swapping red and white)

Measure the voltage between the two 1k resistors (A-).
It should also be ~2.15volt.

Measure the voltage between A+ and A-
It should be less than ~20mV.
If not, then the two 1k resistors are not matched close enough.

I assume you have used a calibration sketch.
Leo..

3

You may need 0.5% or even 0.1% low tempco resistors for the reference arm of the bridge, standard 5 or 10% carbon composition resistors are not going to give useful results as the values will be too different and will
drift all over the shop. 1% metal film or metal oxide might be good enough, especially if in thermal contact
with each other (cancelling drift with temperature). A small value trimmer in one arm can allow
for mismatched resistance, so long as its a small faction of the total resistance.

You can use an unloaded second 3-wire strain guage as the reference arm too, if that's simpler.