# Raspberry Pi and Weight Sensors

**URL:** <https://forum.core-electronics.com.au/t/raspberry-pi-and-weight-sensors/11717>\
**Category:** Finding Parts\
**Created:** [6 October 2021 12:38 UTC](https://forum.core-electronics.com.au/t/raspberry-pi-and-weight-sensors/11717 "2021-10-06T12:38:46Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Mika180159](https://avatars.discourse-cdn.com/v4/letter/m/ed655f/32.png) [@Mika180159](https://forum.core-electronics.com.au/u/Mika180159)\
**Post date:** [6 October 2021 12:38 UTC](https://forum.core-electronics.com.au/t/raspberry-pi-and-weight-sensors/11717/1 "2021-10-06T12:38:46Z")

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Hello, I wanted to quickly check the compatibility of the following parts before I purchase them.

Goal: To use weight sensors for a scale-like function with the Raspberry pi 3b+.

Parts I want to use:

SparkFun Load Sensor Combinator  
([https://core-electronics.com.au/sparkfun-load-sensor-combinator-ver-1-1.html](https://core-electronics.com.au/sparkfun-load-sensor-combinator-ver-1-1.html))

Load Sensor - 50kg  
([Load Sensor - 50kg Australia](https://core-electronics.com.au/load-sensor-50kg.html))

Raspberry Pi 3 Model B+  
([https://core-electronics.com.au/raspberry-pi-3-model-b-plus.html](https://core-electronics.com.au/raspberry-pi-3-model-b-plus.html))

SparkFun Load Cell Amplifier - HX711  
([https://core-electronics.com.au/sparkfun-load-cell-amplifier-hx711-38610.html](https://core-electronics.com.au/sparkfun-load-cell-amplifier-hx711-38610.html))

And Maybe some Jumper cables.

If someone can let me know if these parts are compatible with one another, I would greatly appreciate it. Thank you.

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<div class="post-metadata">

**Author:** ![James46717](https://avatars.discourse-cdn.com/v4/letter/j/e5b9ba/32.png) [@James46717](https://forum.core-electronics.com.au/u/James46717)\
**Post date:** [7 October 2021 03:35 UTC](https://forum.core-electronics.com.au/t/raspberry-pi-and-weight-sensors/11717/2 "2021-10-07T03:35:34Z")

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Well.  
The HX711 should be compatible with the Pi 3B+, 2.7 to 5V range, Pi GPIO pins should work direct to HX711 Data & Clk. (Pi GPIO 3.3V logic). A google search lists Python & C++ libraries on Github for the Pi (no idea if they work though, dont have a HX711 to test).

But, The Sparkfun board has 4 wires to connect to the load cell; the load cell listed seems to have only 3 wires. The link to the specifictions does not work, both on Core Electronic & Sparkfun web site. Until I had a good understand of why there is only 3 wires and can I use them with the HX711, I would be hesitant to buy. This device has 4 wires and probably would work but is only 5kg.

> **[Load Cell - 5kg, Straight Bar (TAL220B) - SEN-14729 - SparkFun Electronics](https://www.sparkfun.com/products/14729)**
>
> This straight bar load cell (sometimes called a strain gauge) can translate up to 5kg of pressure (force) into an electrical signal.

Maybe contact Sparkfun to see if you can get the specifications.  
Regards  
Jim

EDIT: A little more googling and I think you would need 2 or 4 of the 50kg load cells or 2 resistors to connect it to the HX711. The load cell is just 2 resistors, one +ve strain one -ve strain.  
This video shows you how.

[![](https://img.youtube.com/vi/LIuf2egMioA/maxresdefault.jpg "Arduino Scale with HX711 and 50kg Bathroom Scale Load Cells | Step by Step Guide.") ](https://www.youtube.com/watch?v=LIuf2egMioA)