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Why I Wish I Was A Hardware Hacker

In our lab, we have a device that we call the Minus 80. We call it that because it is a freezer that is meant to store our samples at -80°C, or -112°F. For our purposes, as I understand them, this is not as much overkill as you might think, and there are people who get very concerned when it drops below, or rather, when it pops above -70°C. Drag out from the wall and point the big fan at the coils concerned. Conversations with HVAC guys are so loud you can hear them on the other side of a closed door concerned. Last summer, environmental issues surrounding this and other instruments (here meaning "not a computer") were a primary concern that affected use every day.

The unit in question has a digital readout of the current temperature, on a glowing LED mounted at about shin-height, which is not optimal if you're hoping to monitor the temperature. Which leads me to something that I am very sure I saw on the Ben Heck Show, or else on Make. An LED takes a current to light but also four signals to show the number. At least I think so; it's been over a decade since I last tried working with a breadboard. So, given the signal feeding the digital readout, we could run that into something like an Arduino, and from there through more normal means into our database, where we could do alerting should the thing get too warm when nobody is looking.

Anyone who knows me knows that I love taking data in one form and turning it into another. Web to RSS. RSS to JSON. CSV to PNG. If I can get the temperature out of the freezer — the temperature data, that is — I am sure I can do with it whatever I need to. It is that physical step that befuddles me. Yes, I have been annoyed for a good long time about the Minus 80's lack of serial or USB interface. Now, I have a sense of how to I could actually get there myself.

Not that the boss would let me take a soldering iron to his Minus 80. Which is a little more frustrating....


  1. Seems like you could point a webcam at it and use OCR. No solder required.
    Or if you wanted to get really arduino-happy, you could use fourteen separate photodiodes, one for each segment of the display.

  2. That would make it a trip hazard. I really must give you a tour next time you come up here.

  3. The photodiode idea would at least not be a trip hazard. It would be a soldering workout though, to be sure.