DIYmalls 8 Stück Wägezellen 50 kg Gewichtssensor Halbbrücke Dehnungsmesser Menschlicher Körper Digitalwaage + 2 Stück HX711 Verstärker AD-Modul für Arduino

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

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.

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

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.

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.

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.