Adding an auto-shutoff to the simplest of drip coffee makers

[Jerry Pommer] and his wife have relied on a percolating coffee pot for years. We have fond memories of camping trips with these things; they make great coffee which tastes even better on a cold morning in the back woods. But a recent package from the stork means that they no longer have time to sit and watch the coffee perk. After several days of boil-overs [Jerry] switched to this very basic drip coffee maker he salvaged from the trash pile. It has one switch that turns it on and off and nothing else. In order to make sure he doesn’t forget to turn it off, he hacked together his own shut-off timer for the device.

His write-up is all back story, but the 34 minute video embedded after the break takes us through the hack itself. We like it that he starts by discussing the different options that he could have chosen. Of course it might have been a microcontroller, or a 555 timer keeping time. But in the end he went with a simple resistor-capacitor timer. The carefully calculated component pair drives a Darlington transistor which keeps a relay closed. When the slowly draining capacitor lets the voltage drop past a certain threshold it also kills the power to the hot plate. In this case it will only stay on for about a half hour.

Comments

  1. Greg says:

    Wait, no raspberry pi?

    Seriously though, it is great to see someone that hasn’t forgotten how to actually build a simple circuit.

  2. fartface says:

    Where the hell did he find one that did not have auto shutoff? It’s been required safety for over 5 years now on even the cheapest junk.

    • Nardella says:

      Dude, read the article, it is from a trash pile.

    • Sperryfreak says:

      We picked up our drip pot at Target last year for about 12$ it doesn’t have a timer. We have a post it note on the door that says remember to turn off the coffee pot.

    • Sven says:

      Maybe where you live, i have never heard of a regulation like that in .se though.

      There is a regulation requiring an outlet with a timer for personnel coffee pots and hot plates at government owned facilities such as schools and hospitals but no general regulation.

  3. Jerry Pommer says:

    Thanks! The final values chosen actually keep the hot-plate on for three hours before auto-shutoff.

  4. Pete says:

    34 minute video? How many minutes of actual information? Who has sat down and watched the whole thing?

  5. UltraApple says:

    What no Arduino? Everyone knows that all good hacks use an arduino….. :-D haha

    Simple cheap and effective. I like it! Keep up the good work!

  6. Chris C. says:

    Both the delay and video length seem unusually long for an RC timer. I started watching the video just to see what style it’s in.

    Got a giggle at 0:10 – “We’ve used a percolator for a lot of years, but we just had a new baby, and she requires a lot of…” For some reason, I expected the next word to be COFFEE. :) Maybe because I’m a little twisted, and haven’t had my coffee yet either.

    I admit I didn’t make it past 3:12. But it seems to be a good beginner-level video tutorial.

  7. echodelta says:

    I picked up a “pod” type of coffee maker set out at the curb. These use a prepackaged amount of coffee in a filter-bag-pod at 4 to 5 times the cost of the normal bulk style. Here’s the hack. Just use a Melita cone on top of your fav mug, fill it’s very cheap filter with just the right amount of grounds. Fill the tank on the pod machine with fresh water and hit the one serving button. Presto a super cup for the lowest price, no pods no high priced cup o joe. The Melita started the filter-cone method and is simple, yes but this makes it full auto.

    • ewertz says:

      At least one of the major makers of these things now sells a pod-insert that is a filter, allowing one to use one’s own ground coffee.

      Otherwise the use of the disposable coffee pods are just wrong on SO many levels…

  8. Hack Man says:

    Dial type timer control = $4 prepackaged solution. Listed and retrofittable to any 15A device. Variable turn off limits as well.

  9. F4R4D4Y says:

    I’m all for hacking… but for practical reasons, I would have bought a $9 coffee maker.

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