Load cell balance with 12v motor and wheatstone bridge

I want to couple 2 load cells about 8m apart.I want to set up one load cell to which I can apply, and vary, a load. I want to set up a 12v/10a motor and mechanical linkage to apply or reduce the load (run in forward and reverse) on the second load cell to achieve balance using the wheatstone bridge principle.
I have 4 50kg load cells, load cell amp, load combinator, Redboard, relays etc. The arduino requirement has lost me. Can anyone help with a simplistic solution?
Bruce Atkinson

Hi Bruce!

I’m not entirely clear on what you are trying to accomplish, could you please draw up a simple sketch to help me get my head around it?

Hello Stephen

Thanks for contacting me.

I have wired up the load cells, amplifier, combinator redboard. The two ‘spare’ load cells have screw loading arrangements as ‘trimmers’. I am unable to decifer what to do with my computer and redboard. Is there a relatively simple way I can get an output (

resistive?)to drive the motor. I have set up the system with ‘pots’ and it works ok, but my load sensing does not have sufficient movement , so I need to use load cells. I have not connected my computer to the redboard. I saw a suggestion I could wreck the board with the wrong o.s. ( I have windows 10).

Any advice on what to do or where to go is much appreciated.

Wiring schematic attached.

Cheers Bruce

Hi Bruce,

There is no danger of messing up your Redboard from connecting it to a computer. You will need to connect it to a computer to program it.

I recommend you check out our Arduino Workshop for Beginners, it has all the basics you need to get started using your Redboard for projects:

You can find some information on controlling a motor with Arduino(redboard) here:

Hello again Stephen
I have failed to get a sensible resolution to my problem. I have been able to install a code into the redboard, but not one that does what I need. Writing my own code is beyond me. Can you please provide me with an appropriate code for the system, ie 4 load cells wired as wheatstone bridge thru combinator then to amplifier and to redboard. I want to be able to detect a variation in one load cell due to an applied force, then apply a force to a second load cell that achieves balance electrically via the wheatstone bridge principal. I need a code for the redboard that provides me with a workable dc (5v?) output on pins to operate the mechanical loading operation to achieve the electrical balance.
Bruce Atkinson

Hi Bruce,

Unfortunately I can’t write the code for you. If you break your problem down into parts I’m happy to help with any specific questions or take a look at any code that you’ve written and give feedback!

Hello Stephen
I remain unable to advance my project. I wonder if I do not use the redboard but simply connect the four load cells to the combinator and then to the amplifier what outputs should I expect and from which terminals on the load cell amp. I have a 4.5v battery on the combinator. I am unable to establish if I have a wiring (soldering) problem without more information. I think/hope I may be able to operate a remote control relay somehow from the amp terminals
Bruce Atkinson

Hi Bruce,

I won’t be able to help you build an analog circuit to control your device with these parts. There isn’t enough information provided in the datasheets to be able to use them in this way.

As far as the code goes, you should forget about the whetstone bridge, and just have the two load cells connected to the redboard, and the motor driven by a motor controller connected to the same redboard.

here is the basic layout of some psuedo code for you:

while True:
    if loadCell_1 > loadCell_2:
        output motor counter clockwise
    else if loadCell_1 < loadCell_2:
        output motor clockwise

Hi again Stephen
My project is to have 2 load cells one of which is subject to varying loads. The second load cells is subjected to a load provided by a 12v motor and linkage that imposes a varying load equal to that on load cell 1, then stop Prof. Google is of the view that the redboard is not sensitive enough to respond to the load cells without amplification. My thought now is to use 2 load cells through separate amps and maybe separate combinators and use the redboard with a motor controller to achieve the forward/reverse function. The wheatstone bridge was to provide the balance process necessary for my project. I am afraid I would still not know which terminals to connect to on the redboard for the amp in, and motor control out, and how to program the redboard. The system works fine with pots and wheatstone bridge but I need to use load cells!


Bruce Atkinson

Hi Bruce,

The Arduino isn’t too hard to learn, and it’s all very well documented so any questions you might have you will be able to find an answer for. I’d suggest going through our workshop and trying some simple projects to get your head around it, then return to this one with a bit more Arduino knowledge!

Best of luck with your project!

@Bruce62422 I am happy to give you some basic project guidance if you wanted to reach out to me?

1 Like

I would very much like some guidance with my project. I want to use 2 load cells probably (but not necessarily) with a wheatstone bridge arrangement.

I want to have 1 load cell to which I apply a varying load.

The 2nd load cell (that would be approx.5m away) is subjected to a load applied by a 12v motor and linkage so that the load applied exactly matches the load on load cell 1.

The 12v motor must then stop, but must be able to run in either direction to achieve a load balance.

I have no trouble achieving this with potentiometers, but load cells are far better suited to my project.

I have a test rig with 4 - 40kg load cells wired to a load combinator (with 4.5 battery) and from this to a load cell amp. (2 load cells active and 2 passive, maybe for calibration).

I have connected VDD/VCC to 5v POWER and GRD /.GRD on the redboard and also a 12v power supply.

I would like to know which terminals to connect from the amp to which terminals on the redboard?

Which terminals on the redboard give me useable (5v?) output?.

Can I get forward and reverse signals from the redboard?.

Should I get measureable outputs (with an ordinary multimeter) from terminals on the load cell amp (or elsewhere?).

I would like to be able to do a basic check on my workmanship!

I would also need some guidance on programming the redboard some of the info. on the net seems wrong

The ultimate arrangement would have wireless interconnection between the load cells.


Bruce Atkinson

1 Like

@Bruce62422 shoot me a PM and ill give you my email address.