I have an hx711 ADC module with 4 50kg load sensors wired in a wheatstone bridge (for a maximum load of 200kg).

When I apply load to the sensors, the resulting values for increasing weights appear to be non-linear, which is the opposite of what I would expect.

I've tried connecting the module to both a Raspberry Pi and a Wemos d1 mini (esp8266) and get the same results each time. I've also tried rewiring the bridge in different configurations, but only one gives any results.

The results I see are as follows:

0kg: 498,000

1kg: 500,000

10kg: 505,000

25kg: 530,000

100kg: 550,000

As you can see the 'correction factor' to grams is approximately:

result / 500 / weight in kg

Is this likely to be a fault with the ADC module, an issue with wiring, or something else I'm doing wrong?

The ADC module spec: https://cdn.sparkfun.com/datasheets/Sensors/ForceFlex/hx711_english.pdf

The load sensor spec: https://ae01.alicdn.com/kf/HTB1ZDtuKXXXXXX9XVXXq6xXFXXXI/201492522/HTB1ZDtuKXXXXXX9XVXXq6xXFXXXI.jpg

Wiring schematic (sorry for poor quality - not used the tool before!). The load cells are connected:

1: red -> E-, Black -> 2, White -> 3 2: red -> A-, Black -> 1, White -> 4 3: red -> A+, Black -> 4, White -> 1 4: red -> E+, Black -> 3, White -> 2


simulate this circuit – Schematic created using CircuitLab

The voltage in (VCC) is nominally 5V - measured at 5V on RPi, and 4.8V on Arduino. The Excitation voltage is always 4.17V, regardless of VCC. I don't have accurate enough multimeter to read A+/-.

  • \$\begingroup\$ do you have any data on the load cell? \$\endgroup\$
    – danmcb
    Dec 30, 2018 at 14:50
  • 1
    \$\begingroup\$ How are the FOUR sensors wired? And powered? And how does the ADC get a reference voltage? \$\endgroup\$ Dec 30, 2018 at 14:52
  • \$\begingroup\$ You need to post your schematic. \$\endgroup\$
    – JRE
    Dec 30, 2018 at 20:50
  • \$\begingroup\$ Have updated Q with load cell data, wiring and some extra info. Thanks! \$\endgroup\$
    – match
    Dec 31, 2018 at 12:46

1 Answer 1


Having revisited this problem, I now have a solution, which is embarrassingly not an electronic one!

I wasn't mounting the load cells correctly.I had naively positioned them between 2 boards - however this meant that the central part wasn't able to flex properly against the outer ring.

Mounting the cell using the outer ring of metal only, and leaving the centre free-floating and the output became linear and scales consistently as expected.


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