2 Sets 50kg Human Scale Load Cell Weighing Sensor Resistance Strain Half-Bridge Sensor + HX711 A/D Amplifier Weight Module DIY Kit Compatible Ardu...

The 1st photo shows a board with "MH" stamped on it. The actual chips they sent do not. They are different and look like the ones shown in photo 3. The boards are physically different. There is a lead from the HX711 "rate" to GND which is supposed to set the rate at 10 SPS per the data sheet. The HM chips don't have this (maybe imbedded, not sure). Other than that, I'm not sure the all the exact differences in the board. All I know is that they don't work. I bought a single board and 4 gage package from a different seller. It had a HM printed on the board. When hooked up to an Arduino, everything works fine. The chips reads (as well as the system can anyways) Since this one worked for my project, I ordered 2 sets of 2 each from this seller (so I could have a total of 5). figured I'd save a few buck getting them 2 at a time. They do NOT work. I tried everything including writing a bit-banging sketch to verify that it just wasn't incompatible with the HX771 library I was using. They don't work. The program hangs up after the first (erroneous) reading. I've tried 3 different HX711 libraries. I tried physically cutting the "rate" lead on the board (even though this should be correct per the HX711 data sheet). Nothing. The 4 boards from this seller do not read. The one with the MH does fine. There's something wrong with these. I don't know exactly what, but there is something wrong. OK, so after pulling out my hair for more time than I wanted, I figured it out These boards are not wired properly. There is a pin for AGND on the HX711 chip that needs a ground. it's right there in the diagrams they have attached. instead, they just wired it to "-E". There's enough voltage bleed to totally screw up the circuit. This is bad design and incorrect. There is a solution... wire a jumper from -E all the way over to Ground. That got them working again. reading seem normal now. Although you shouldn't have to rewire a faulty design.

I ran mine into a nodemcu. I found one of the amplifiers was dead but it may have been my fault, I initially hooked it into the 5v feed. I found a great tutorial on youtube that showed how to setup a whetstone bridge with the hx711 and that set me on the right path. The most challenging part which I didn't initially understand was to route out a board to set the sensors into so they were suspended properly in such a way to allow a reading. Initially I just hot glued them flat to a board and that doesn't work. I used a 1" forstener to make a 1/4" deep hole in a piece of plywood and then glued them in place. In the next iteration I'll go dig for 3d printed feet since I've seen reference above to that.

Load Cell Amplifier NOT working " HX711 not found" not find in program Do Not Buy

You have to continually tare the weight and even then its not very accurate and unstable

My biggest complaint with this is that there isn't enough documentation I could find with examples for common platforms and specific wiring instructions. But once I finally found and processed what I needed to know, it seems to work pretty well with my Pi Pico board here. For anyone else struggling to get two of these wired up, wondering if there need resistors involved or if some leads should be connected to supply voltage / ground: STOP. Just stop all of that. It's much easier than that. This is what worked for me, to wire up two to one HX711: Connect the white wire of one unit to the black wire of the other - connect both to E+ input Connect the other white / black wires together and connect those to E- input Connect the red wires to A+ / A- inputs Connect HX711 "DT" and "SCK" to Pico/etc GPIO pins (does not need to be analog), connect power and ground. From micropython, install HX711 (with upip or just find and save the file to the device manually) from HX711 import hx711 driver = HX711(d_out = {the GPIO pin# you connected "DT" to}, pd_sck={the GPIO pin# you connected "SCK" to}) driver.read() -> 45321 and that's it. You'll have to calibrate it to an implementation specific minimum / maximum value within your code, how you actually mount it and what weight it holds without any load all change the specifics too much for a generalized solution Good luck! I'm not sure if it matters which one goes to which (e+ versus e-, a+ versus a-), my setup here has worked like that with the first selection, I suspect it works either way.