I recently purchased a 50 kg micro load cell (robotshop.com/ca/en/dfrobot- … rface.html) and want to use them together.
Currently they “work” together, BUT when I modify the setScale function (as seen in the wiki code: dfrobot.com/wiki/index.php/W … _Module_V1) the value needs to be very low in order to get correct weights. This causes the results to fluctuate, showing values ± 5g from the actual value. When I use the 1 kg load cell that came with the DFRobot HX711 I don’t have the same problems.
I am wondering if there are any additional parts that I need to purchase to make the load cell and HX711 interface work better together. A voltage amplifier perhaps?
Any help would be much appreciated!!
It normal that using a sensor will larger scale (50kg instead of 1kg) with the same interface board will give more error.
The datasheet for the RB-Phi-120 says it has a precision of 0.05% of full scale.
In your case, an error of 5g for a load cell rated at 50kg means you’re experiencing a precision of 0.01% which is five times more precision and is pretty good.
If the readings are fluctuating up and down by 5g around the correct value, then you could increase the precision by doing some digital processing of the signal read. You can try to do some over-sampling of the sensor’s value and doing an average. For example, sample the sensor 10 times and do the average of it.
Another option would be to use a load cell with a smaller scale, such as RB-Phi-119 rated at 20kg or RB-Phi-118 rated at 5kg.
Hope this helps.
Ok I get it. I guess it is too much to expect a 7 dollar load cell to be within 0.05%. I’m going to try and find a more accurate 50 kg load cell somewhere else.
Thanks for your reply!
We’re glad we can help. If you find a load cell that meets your need, can you let us know as we’d like to add it to our catalogue.
Thanks,
