Load cell 50kg (3 wire), HX711

Hi,

I bought HX711 and some load cells. They are 50kg and have 3 wires. This load cell

I downloaded library from HERE.
Built circuit as HERE.

I haven´t found many circuits with 3 wire load cells.

I don´t know, if I have any problem with soldered wires or connections. The values are jumping up and down...
-Arduino clone CH340

Thanks for any help
Best regards

Lukas

You are better off using two loadcells. connect them to make a full bridge and get rid og the voltage divider.

A bridge with one load cell and two resistors will only work if the resistors are exactly the same.
You might have to select them with a DMM.
Indeed better to use two (or four) load cells if you can pull that off mechanically.
Mind the polarity. With added weight, one side of the bridge has to increase and the other has to decrease voltage.
Leo…

Could you direct me by some schema or link..

Thanks :slight_smile:

There is a "hookup guide" on that page.
Leo..

I have found load cell wiring for 4 wire only.
No luck :confused:

A 4-wire load cell is just two 3-wire load cells in one.

Measure the resistance between the wires of your 3-wire load cell.
Find the two wires with the highest resistance.
Those are the two wires for the excitation voltage (+E and -E).

The remaining one is the load cell "output", that goes to +A (-A for the second cell).

So...
Connect the first laod cell to +E, -E, and +A.
Connect the second cell to +E, -E, and -A.

This only works if the two load cells get opposite forces.

If the two load cells get both the same force (e.g. when both mounted on the same side of a platter),
then swap +E and -E of ONE load cell.
Leo..

Still cannot get values from the sensor when run THIS example :-(.

Wouldn't be problem with sensors or the module ?

Thanks :--)

First make sure the load cells are ok by measuring the voltage between A+ and A- with a DMM.

It should be close to zero millivolt without force.
Leo..

Image of schema

Yes the voltage is close to 0.

0.2mV