Soda Fridge Hack To Fix A Lazy People Problem

[Paul] participated in a hackathon at work and created a hack to help solve what was ultimately a people problem. A soda fridge at work wasn’t getting refilled when empty. Instead of trying to make people less lazy, [Paul] went with making the fridge more needy.

The first thing [Paul] did was make a soda fridge refill sensor from a scale. As the fridge got emptier, it got lighter. The scale senses that and can decide it’s time for a refill. The only part missing was how to read the output from the scale. To do that, he took an unusual approach.

Soda Fridge on Hacked Scale
Soda fridge on an analog scale with color sensor reading the dial

The soda fridge sits on an analog scale with a dial. [Paul] saw there was no need to measure the exact weight of the fridge, only to detect a refill threshold. He came up with a simple hack: colored paper attached to the scale’s dial and an Arduino with an OSEPP COLOR‑01 color sensor pointed at the paper. The dial moves in response to the fridge’s changing weight, and the color sensor reads the color of the paper as it moves under the sensor. With a little bit of trial-and-error calibration and some barely modified sample code for the sensor, it was possible to reliably detect when the fridge required refilling. With the sensor done, it was time to use it to solve the lazy people problem.

In a way, the root problem wasn’t that people couldn’t be bothered to check if the fridge needed a refill – it was that the right people weren’t finding out at the right times. This resulted in spotty refilling as well as soda not being ordered when needed. This hack means that the fridge can now actively announce its state, which now allows things like notifying people via email that it is their turn to refill and re-order. It turns out that a fridge that can tell people what it needs has a much better chance of being serviced, compared to a one that has to wait for people to check up on it.

We’ve seen people interface directly to the load sensors in weight scales before, but this hack took a completely different approach.

Thanks to [Paul] for sharing.

13 thoughts on “Soda Fridge Hack To Fix A Lazy People Problem

  1. This isn’t really new. There’s that infamous soda vending machine that was online, I think before the web but can’t remember the exact period. They fixed it so they could tell how many cans remained, even keeping track of when each slot was loaded (the longer the can has been in the machine, the colder it would be). It probably was the first “internet appliance” except I think it technically was an arpanet appliance.


  2. Do you need to recalibrate it for diet soda?

    What if someone places something atop the unit?

    Couldn’t you just use the color sensor to detect a colored area exposed by removing the cans?

    1. Maybe a camera on the ceiling (and the ceiling of every shelf), and some weird color that the cans will never have (maybe not needed, just something the top of the cans will never have) on the shelf floor, i think it might be pretty easy to calculate the percentage of the floor color shown, and then when it gets to 80% or something, make the alarm. Probably would be able to do that on an arduino, but naturally ESP would be better since it is a wifi chip.

      Maybe take the picture when the door is opened, that way you might not need separate lights either.

      1. Altough my idea would require enough space between the shelf floor and ceiling. Some wide angle lens would make the distance shorter, but still. If the the space is just about can height, then it’s not going to work.

  3. Now if this could be beer… A good hack for sure. I guess we aren’t in Japan where they have vending machines that have beer.
    As for recalibration, our bodies don’t either on some fronts. Die-t soda!

  4. Why not just use a load cell and measure the difference, Or some chunk on the needle and have a cardboard disc and hand wound coil to measure the difference in, Or take one of those old serial mice with the massive Optical scroll disc and attach that to the shaft and put sensors inside the scale.

    This all seems like odd.

  5. Our air pots at work need this with the addition of snapping a pic of the people who try to get coffee when it’s empty and the last one gets erased only when the coffee gets refilled. Non-brewers can get their pictures posted in the break room.

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