8pcs Load Cell 50kg Weight Sensor Half Bridge Strain Gauge Human Body Digital Scale + 2pcs HX711 Amplifier AD Module for Arduino

I made a scale using these sensors and ADC board. To my surprise it turned out to be pretty accurate. I was able to achieve 0.5 % accuracy with this setup

The product appears to be in acceptable condition, and was shipped out promptly. The sensor wires are the thinnest I have ever tried to work with, and had a foul odor. It was very difficult to strip back the insulation using a standard pair of wire strippers. I have yet to see how well they perform.

Overall, it is a good deal. Looking over the IC specs and checking the PCB layout, I found out that analog ground is left floating instead of getting connected to the system ground provided by the micro controller connections such as into an Arduino. The picture I posted shows the black cable I added fixing this mistake. Otherwise, analog ground is sitting ~ +570 mV above the system ground and this is probably due to a parasitic diode turning on in the circuit but not sure. If so, it may make it more susceptible to temperature fluctuations. Hopefully, the fix improves the performance of the load cell interface but I had not have a chance to compare it.

This is a great DIY strain gauge kit. Actually, it’s a 2 pack, with enough parts to build two scales. It’s worth noting that the strain gauges that come in this kit (8 total) are single gauge load cells, sometimes called “load sensors” and not complete 4-wire load cells. You need to set 4 of them up (with a single HX711 module) in a Wheatstone bridge configuration to actually turn them into a 4-wire load cell that can measure weight. With 8 load sensors, and two HX711 boards, you have enough parts to build two complete scales.One of the best things about this vendor’s page is that they show you the schematic of how to hook up the load sensors in the proper Wheatstone bridge configuration and connect it to the HX711. You can also find an excellent tutorial online from Sparkfun that includes Arduino sample code for this type of scale. I followed the tutorial, using an Arduino Uno, and my scale worked perfectly (after adjusting a few calibration factors, etc). I only built one scale, so I didn’t test the other half of the kit. The wires are very small, so I couldn’t easily connect Dupont wires for testing. I had to solder almost everything. I didn’t want to do it all twice just to test. The picture shows the output of my scale as I add a 10 lb dumbbell, and then another 5 lb dumbbell, and it was fairly close. Certainly close enough, given the fact that I don’t know the “true” weight of my dumbbells (they’re probably not perfectly accurate themselves).If this is your first experience with load sensors, I’ll briefly mention how to mount them properly to get good readings. The middle of the load sensor is only connected on one side to the outer ring, in a cantilever configuration, right under the spot where the wires come out. Well, that inner part of the sensor needs to be floating for the cantilever to work. So you need to mount the outer ring to your scale frame, and the inner piece should be free floating. I routed out a small cavity for this, then just superglued the sensors to the wooden board (see pictures). It’s this inner sensor piece that will make contact with the ground when you set the scale down. As you load the scale, this inner piece will bend slightly (on each of the 4 sensors), and the sensors detect this bending via very small changes in resistance. The Wheatstone bridge and HX711 amplify this small change into something that can be interpreted as a weight.For getting enough parts to build 2 scales, I’d say this is a great deal. The quality is good, and everything worked the first time. And, the schematics are right here on the product page, which is a huge bonus, plus lots of sample code can be found online. I’m giving this 5 stars. I had a lot of fun building this and playing with load sensors.

I don't think these are the highest quality but they are good enough for most purposes and pretty cheap.

They do exactly what they say they'll do. The real magic comes from the coding you do. You get the data in raw form, so you'll need to convert that data into your desired units, along with how accurate you want it to be an 'int' vs. 'float' etc. However, you will have to look up all of the conversion formulas yourself and plug it in. Fun to play around with!

One of the HX711s was fine, but the other was missing its R9 resistor. I haven't yet tried soldering on a 1.2K ohm resistor to see if that's enough to fix it, but either way, I shouldn't have had to.

Ich habe die Sensoren bestellt, um eine "Gute-Nacht" Automatik im SmartHome zu basten - die Zellen unter den Bettrahmen verstecken und am Gewicht erkennen ob die vergessene Beleuchtung etc. abgestellt werden kann.Im Paket zwei Set's, reicht also für das Doppelbett. Die HX711 kommen in einer Anti-Statik-Tüte, sind mit den Wägezellen aber sonst ungeschützt in einen Beutel gequetscht.Die sehr dünnen Anschlusskabel (0.3mm?) reichen für ein 40x40 cm Quadrat mit dann diagonal zum HX711 geführten Datenleitungen.Eine Anleitung zum Verschrauben, Verkabeln oder gar eine Code-Beispiel wird nicht mitgeliefert, nur die Produktbilder zeigen die Verkabelung von 4 Zellen untereinander und den Anschluss einer Zelle.Programmcode, Bibliotheken etc. muss man sich selbst suchen (Suchbegriff hx711).Das Bild aus dem Testaufbau mit Phyton und einem ESP32 zeigt in gelb markiert, dass die Zellen funktionieren - Kalibrierung und Umrechnung in Kilo fehlt da noch.Fazit:Belastbare und stabile Wägezellen, jedoch 0 Anleitung oder Hilfestellung.Die Anschlusskabel sollten zudem deutlich stabiler sein und die Verpackung geht geschützter.Für den Preis nur "Befriedigend" und etwas für DIY's, die wirklich alles selbst rausfinden wollen =3/5

I would strongly recommend that anyone ordering this kit have at least some knowledge of analog electronics. Yes, you heard that right, analog! It may be a digital world, and this kit does have a digital interface, but it is the analog side of this that was the biggest challenge for me when doing some prototyping.These load cells are half bridges, and as such they need some additional components if they are to be used singly. If used in groups, no additional components are needed, but some interesting wiring is required. The diagrams and description shown in the product info are helpful but not complete. For example, when wiring for a single load cell, I wired it exactly as shown - using standard carbon film resistors. This did not work. I knew my two resistors had opposite errors (one was above 1K Ohm, the other was below). This threw out the reference bridge too much and I was unable to get readings from this set up. Had I used precision resistors I suspect it would have worked fine. I was able to get a 2 cell system to work, where I was essentially using one cell as the reference resistors and the other as the load sensor.However, even with this configuration, my sketchy connections were a big issue. I was just wire wrapping the load cell wires on the pins of the header. This was not good - it resulted in too much resistance changes in the connections, and my readings would be stable for a moment but then would start drifting all over the place. I was able to test for long enough to ensure that the bridge was working and that the load cell was measuring properly, but it wasn't stable or very accurate.I would assume that had I properly soldered everything up and used high reliability connections to the header pins, I would have had nice stable readings and accurate zeroing.The vendor states "Simple and easy to use, with a lot of supporting libraries and information on the web." in the product description. It looks like they are relying on the end user doing their research to get this up and running. That said, I had no issues finding a video online that explained how to hook up the board to the Arduino and find a code library to load up. That was the easy part. As I said before the analog side of it was much more of a challenge for me.Be warned that if the load cell is not wired up properly, the readily available Arduino test code out there may appear to hang up as it will error if it can't properly tare the readings or otherwise make sense of them. At first I thought this was a power or digital issue with I2C communications but no, it was an analog issue due to the inaccuracy of the reference resistors I was using.So bottom line, care and attention is required, as is research. Once you get everything sorted out, this should work as intended. Just be prepared for some potential bumps in the prototyping process.

Die Wägzellen und HX Sensor machen insgesamt einen guten Eindruck.Bisher habe ich 1 Set zum Testen zusammengesteckt und mit Arduino getestet.Es gibt zum Glück einige Beispiele, sodass schnell getestet werden kann.

I had to download the hx711 module which set up the clock rate and data transfer. Then wrote a simple C program to interface with the my Arduino and display. I recommend having a momentary button connected to one of the inputs so you can tare. Once set up, I was able to read the raw data. You can add a line of code to convert this to units. I had to use known weights in order to get an accurate calibration. All of the load cells read relatively close together and seems meets their specifications. I plan on using these for corner loading an RC car. Since this kit only comes with 2 AD converters, I will need another 2. Overall, pretty neat load cells.