Hey guys, this is my first post on here and i am fairly new to electronics and programming. I am trying to use an hx711 adc converter to measure precise weights from a 300g load cell to arduino serial. I know that this adc will work for larger load cells but I do not know if it will work well with my 300g one (not enough gain amplification? ). I have been trying get a good reading but I can't seem to even get it to change when I apply pressure. I also have an ina125p that I could not get a good reading on either(I don't know what resistance to use). The precision wold not be good but atleast it would be a start. I have been uploading libraries from github to use for the two ic's.
Any help would be appreciated.
Ps: If someone can draw me a schematic, and write the code that achieves greater than 0.01g accuracy on the load cell, I am willing to purchase the plans. (you are not limited to the ic's I chose)
Where did you get your load cell from, and have you checked it with a multimeter to find out how many ohms there are between the various wires? The E+ and E- wires (usually red/black) should have a resistance equivalent to the A+ and A- wires (usually green/white). If you understand what a wheatstone bridge looks like it will be helpful.
For the INA125P you start with a gain setting resistor of ~470ohm, check the output, then try with a ~5 ohm resistor. That should result in one reading being high and the other being low -- if it doesn't then something is amiss. Assuming there isn't any other issue, you continue searching for the proper gain by using resistances between 470 and 5 until you get a reading that is somewhere in-between. Basically you're playing a high/low game. It can be exhaustive and in my experience requires you to be accurate within just one or two ohms.
Achieving a one part in 30,000 load cell system (300g / 0.01g) is not for the faint of heart or for someone new to electronics. See, for example, this doc