Digital Scale Strain Gauge Weight Sensor
We took a $20 digital scale from Target and hooked it up to an amplifier and a microcontroller. This video outlines taking apart the scale, wiring it to the amplifier, and the code, as well as an overview of the concepts behind strain gauges and Wheatstone bridges. There's a demo of two live scale apps written in Python near the end of the video.
Note: there's a lot going on in this project, from the cantilever bending to the bridge noise cancellation to the PC graphics code. It's a complicated one, so take it slow.
You can download the microcontroller source code. (Start with one of the projects included with the kit, and modify the Makefile to reference this file.) You can also see the source code for the PC-side software, live scale graph and live can counter.
More Videos and Projects!
Take a look at more videos and microcontroller projects!