Only one style of toaster will work for this project. Here’s you want) will pop back up immediately if no power is
a simple thrift-store test: push the handle down with the flowing to the magnet.
toaster unplugged. If it stays down, you have the wrong
kind of toaster — an electromagnetic toaster (the kind
the arm depresses allowing current to flow; and for converting AC to DC.) Our DC battery will
a circuit board with the electromagnet and rheo- pass straight through, unaltered.
stat (connected to the toaster’s darkness dial). Putting it all together is easier if you can find a
The toaster’s frame and the heating coils can be suitable container; I used an unfinished wood box
discarded, but this is easier said than done: my from a local craft store. Cut most of the original
toaster was built like a tank. A Dremel cutting power cord, attached to the lever switch, and
wheel, tin snips, or some other metal cutting solder the ends to a 9V battery holder. Solder the
tool will help here. other lines from the lever switch to the power
Of course, we don’t want to have to plug this leads on the circuit board — thanks to the bridge
into the wall. The vast majority of a toaster’s rectifier, polarity doesn’t matter. Now arrange
energy consumption goes into generating heat in the pieces in your box as they were in the toaster.
the toasting coils. We don’t want that and neither For the arm, I used a wooden dowel with a brass
does the circuit board; it’s counting on having hook. To make a cup of tea, tie the teabag onto the
most of the voltage dropped by the heaters. Your hook, push the lever down to immerse the tea
circuit board will likely be stamped with something bag, and place your trust in the machine.
like “10V”; regardless of the appliance voltage, As the battery runs down, the timer will slow
the circuit wants to receive no more than 10V. even more, but not to worry. By the time the bat-Since most people like tea to steep a little longer tery gets that low, the voltage will have dropped
than they like toast to toast, a 9V battery will low enough that the electromagnet no longer
work well here — the lower voltage will slow the holds. I estimate that a regular 600mAh bat-rate at which the capacitor charges, and that’s tery should be good for at least 8 hours runtime,
just fine. The problem of how to convert the about 80-100 cups for a 5-minute steeper.
toaster from alternating current (wall socket) to
direct current (battery) is also solved: the toaster Johnathan Nightingale is an IBM coder by day, reality
circuit contains a bridge rectifier (a simple circuit hacker by night, and habitual over-thinker.
