DIY Coffee

Author:DIY Coffee
Language: eng
Tags: COMPUTERS / Computerized Home & Entertainment
ISBN: 9781449323813
Publisher: O'Reilly Media
Published: 2007-03-22T16:00:00+00:00

Note

After a set amount of time, the toaster tea popper lifts the bag from the cup.

Note

Only one style of toaster will work for this project. Here’s a simple thrift-store test: push the handle down with the toaster unplugged. If it stays down, you have the wrong kind of toaster — an electromagnetic toaster (the kind you want) will pop back up immediately if no power is flowing to the magnet.

Of course, we don’t want to have to plug this into the wall. The vast majority of a toaster’s energy consumption goes into generating heat in the toasting coils. We don’t want that and neither does the circuit board; it’s counting on having most of the voltage dropped by the heaters. Your circuit board will likely be stamped with something like “10V”; regardless of the appliance voltage, the circuit wants to receive no more than 10V. Since most people like tea to steep a little longer than they like toast to toast, a 9V battery will work well here — the lower voltage will slow the rate at which the capacitor charges, and that’s just fine. The problem of how to convert the toaster from alternating current (wall socket) to direct current (battery) is also solved: the toaster circuit contains a bridge rectifier (a simple circuit for converting AC to DC.) Our DC battery will pass straight through, unaltered.

Putting it all together is easier if you can find a suitable container; I used an unfinished wood box from a local craft store. Cut most of the original power cord, attached to the lever switch, and solder the ends to a 9V battery holder. Solder the other lines from the lever switch to the power leads on the circuit board — thanks to the bridge rectifier, polarity doesn’t matter. Now arrange the pieces in your box as they were in the toaster. For the arm, I used a wooden dowel with a brass hook. To make a cup of tea, tie the teabag onto the hook, push the lever down to immerse the tea bag, and place your trust in the machine.

As the battery runs down, the timer will slow even more, but not to worry. By the time the battery gets that low, the voltage will have dropped low enough that the electromagnet no longer holds. I estimate that a regular 600mAh battery should be good for at least 8 hours runtime, about 80-100 cups for a 5-minute steeper.

Johnathan Nightingale is an IBM coder by day, reality hacker by night, and habitual over-thinker.

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