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.

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Internet enabled drip coffee

A fresh pot of coffee is never more than a tweet away with the Tweet-a-Pot. It works in much the same way that our Troll Sniffing Rat does. For that build we used a Python script to monitor our comments, and this does the same except that the script read tweets through the Twitter API. It watches for a specific hash tag (#driptwit) and when found it sends a serial command to an Arduino. The microcontroller then writes a digital pin high to actuate a relay, powering up the coffee maker.

Sure, you have to preload the pot with grounds and water, but what do you expect, automatic coffee roasting and brewing? That’s quite a bit more work.

Photographing splashing droplets

When doing those cool liquid droplet splash pictures, you need to time not only the camera, but the droplets themselves. This project takes you through how to build the system to time the droplets and work with camera axe to get the right pictures. PCB files and schematics are available. As you can see, the results are quite nice.