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.

For the source code or more information about our microcontroller kits, go to


jeweleryDigital Scale Strain Gauge Weight Sensor
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  • cathal butler - January 8, 2018 reply

    Hi, I wonder if you could help me, I'm trying to develop a weighing scales  that has a built-in max and minimum alarm. The reason for this is I'm in the process of setting up a weight loss business and I don't want my patients to be able to see their weight. Ideally what I want is for them to stand on the weighing scales and if they go over a preset maximum weight, an alarm will go off and similarly if they go below a preset weight an alarm will go off.

  • saidou D - January 8, 2018 reply

    svp- pouvez vous me faire une vidéo pareille commentaires en francais.

  • michael shulman - January 8, 2018 reply

    Guys! Great video! Can you please try to explain to me one thing that puzzles me for years….every time I use electronic scale( home or commercial in the gym) after a shower with wet feet I Always weigh about one pound+ less then before shower….galvanic?…

  • kitty kat - January 8, 2018 reply

    hi, what are the parts in making a digital scale? i really need it..

  • Josh Haviland - January 8, 2018 reply

    ugh. for under $100 in even 2008 money, you could have just bought a scale indicator and real load cell that provided a serial output…

    seems like a lot of work to make something that has existed for decades.

    and no way that's accurate with cheap bathroom scale stain gauges.

    reference: I do this for a living

  • LeonardoGulli - January 8, 2018 reply

    amazing video man!

  • Arka Rellon - January 8, 2018 reply

    This is what i am looking for!!We need this for our thesis…thanks!!

  • Shaun - January 8, 2018 reply

    Are there smaller/flatter sensors to accomplish this? Looking at the scale it was pretty big but I was wondering if there are any that could be smaller than a mm?

  • Cindy Si - January 8, 2018 reply

    nicely explained guys

  • XXVorteXX - January 8, 2018 reply

    but my sensor has 3 wires, red, black and white , I think the red is (+) black (-) and white is signal, datasheet say 3-10 DCV operation, I used red to + and  black – I read of the white wire  but I dont have nothing in my multimeter even in mV, is right the polarizatation ? and read the white wire how positive and my multimeter and black as ground .

  • Tyler DeVos - January 8, 2018 reply

    Does the scale have to be plugged directly into the computer or can it connect to one of the apps wirelessly thru other means?

  • B.W. Block - January 8, 2018 reply

    good explanation.

  • aryan gupta - January 8, 2018 reply

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  • Zain Ijaz - January 8, 2018 reply

    How much is the CAPACITOR VALUE

  • B Tech Electronic - January 8, 2018 reply

    sir i am mfg for electronic weighing scale in rajkot (india), my reqment is weighing card for class 1 or 2 (200000 counts) weighing scale with .56 inch7segment led in6 digit pls hepl me

  • PistonPackingPete - January 8, 2018 reply

    Very nice tutorial. Thank you.

    (For chiquiviveros, the LM 741 op amp is generally regarded as obsolete, so there are better parts for the price. The TL081 is slightly newer and somewhat better. "The AD620 is a low cost, high accuracy instrumentation amplifier that requires only one external resistor to set gains of 1 to 10,000")

  • TheGerardo74080 - January 8, 2018 reply

    hey dude do you know where can i see how its made an electronico weighing

  • Srečko Lavrič - January 8, 2018 reply

    Great video and chip suggestion. Just what I was looking for. I made a homebrew instrumental amplifier, but it is very hard because of all those resistors must match.

    Thanks again, friend. 🙂

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