In this tutorial I show you how to get a hanging weight sensor for an Arduino project out of a cheap, common luggage/fishing scale and the often used HX711 ADC module.
For a project I needed a sensor to measure a certain weight that is hanging on a string. The weight sensor should have been very small and send accurate data to a microcontroller. I could not find a load cell that was fitting my aesthetical and technical requirements. In the end I figured out that the inside of a standard luggage scale can be used in the same way as a load cell. These scales are small and cheap and are already made to measure hanging weights. With an HX711 ADC module you can transform the analog data into readable data for the Serial Port of an Arduino. I am so happy about this, that I want to share this small hack with you!
- Suitcase/Fishing Scale
- HX711 ADC Module
- Jumper Cables/ Cables
Step 1: Opening the Luggage Scale
After opening the scale you can see the metal construction, that has four cables attached: a black, red, white and green cable. The cables go to a board. We only need this metal thing, with its four cables. This is going to be our load cell.
On the last photo you can see the luggage scale cell next to a common 10kg load cell. Our cell from the luggage scale is much smaller but has the same cables.
The luggage scale I used had dual accuracy: 0 -10 kg, 5g accuracy/ 10-45 kg, 10g accuracy.
Step 2: Connecting Your Hanging Load Cell to the HX711 Module and to the Arduino.
Now we connect our load cell to the module and to the Arduino. Here you can just follow the wiring diagram of the HX711 ADC module. Check before wiring if your HX711 module uses 3.3 V or 5 V.
Step 3: Download a HX711 Library and Calibrate Your Weight Sensor
Follow now the very nice guide from Mybotic (from Step 4 on):
There is a good HX711 library provided and also the calibration is explained in a video.
Step 4: Enjoy Your Tiny Hanging Weight Sensor!
In the end you should have your own small beautiful weight sensor for projects that require a measurement from a hanging weight! I used mine to create a balancing machine.
I hope this small hack can enrich your personal projects!