This load sensor, sometimes called a strain gauge, is the same one found in digital bathroom scales (you know, the ones you use in January for your New Year’s resolutions, and then forget about a month later). This sensor can measure up to about 110 pounds. Check the video below for a simple explanation on how these work and how to use them.
White and black are the outer terminals with red being the center tap. The picture below will give you a good idea what the inside of the load cell looks like. Our load sensor should measure 1000 ohms between the red and white or black wires and 2000 ohms between the black and white wires.
Here’s some additional information on using this load sensor:
Quarter, Half Bridge and Full Wheatstone bridge: Bridge strain Gauge Load Cell Configurations [ [http://www.transducertechniques.com/wheatstone-bridge.aspx]9http://www.transducertechniques.com/wheatstone-bridge.aspx) ]
How to wire up a 3-wire load cell strain gauge and an amplifier [ http://electronics.stackexchange.com/questions/18669/how-to-wire-up-a-3-wire-load-cell-strain-gauge-and-an-amplifier based on the ProtoPic demo http://www.youtube.com/watch?v=Bm6ANv93YjM ]
Robotistan.co: “Load cell usage - Load cell using 3 wire load sensor” [ https://translate.google.com/translate?hl=en&sl=tr&u=https://robotistan.freshdesk.com/support/solutions/articles/12000009562-load-cell-kullan-m-load-cell-using-with-3-wire-load-sensor&prev=search ] has an example for wiring up a quarter Wheatstone bridge, HX711, an Arduino Uno.
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Skill Level: Rookie - You will need a better fundamental understand of what code is, and how it works. You will be using beginner-level software and development tools like Arduino. You will be dealing directly with code, but numerous examples and libraries are available. Sensors or shields will communicate with serial or TTL.
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If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.
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Based on 4 ratings:
1 of 1 found this helpful:
It does take some time to understand how to wire properly. Read the guides, then read them again. Trust me, everything you need to know is there. I used an OpenScale board to connect and manage everything - very happy with results. You do need four of these arranged in a square on a platform, a bit of solder into the open scale board, and a USB cable/host is all you need. Wrote some python on a RPI to make this into a handy little IOT scale.
7 of 8 found this helpful:
I built a dog weight scale using 4 of these, a Load Combinator board, a Load Cell Ampllfier, and an Arduino. It worked and gave good results the first time I turned it on.
This page could use a little more documentation on two things: 1) how to mechanically mount the thing. You must mount it with a cutout below it so the “T” bar is free to bend below the “C” frame. 2) a brief schematic and instructions on how to figure out which wires are which. As it is, the Black, Red, White colors sort of match the Red, White, Blue colors of the Load Combinator. It would be easy to mention: to test the wires measure the resistance between each pair. The wire with the lowest resistance is the “red” center tap. Then measure the other two wires resistance to the Red wire as you push on the sensor: one wire will show a changing resistance, the other won’t change much.
I found all this information buried near the bottom of the hookup guide. It would be helpful to reiterate it here for people who don’t plan to use the load combinator.
1 of 6 found this helpful:
There’s only ONE way to use this thing, according to SparkFun and that’s by connecting four of them to a combinator and load cell amp. I would never have purchased the thing knowing that I would have to spend $40 instead of $10.
It’s not as simple as it should be and there is next to no documentation or relevant help for this sensor. I would not recommend it to anyone. AND PLEASE DO NOT GIVE ME A LINK TO YOUR USELESS “Getting Started with Load Cells” PAGE.
0 of 4 found this helpful:
I still am unable to figure out how it works…
There’s a good tutorial here to help you - https://learn.sparkfun.com/tutorials/getting-started-with-load-cells