How complicated can a toaster be? You can get a cheap one for way under $10 that is little more than a hot wire. However, there are a few little complications. First, consumer products need to be safe — lawsuits are expensive. Second, there has to be some mechanism to hold the toast down until it is done. If you can buy one for $10 you can bet it isn’t some super toast processor running Linux in there.
[Technology Connections] tore one down for you so you don’t have to. The circuitry is simple, and who knew there was a dedicated IC for toaster control? However, the real engineering is in the lowly little handle you pull down to start the toasting.
That little bit of mechanics works as a power switch, a circuit breaker, and does the work that keeps the toast down until it is ready. The lever turns on the power which turns on an electromagnet. When the toaster decides it is done, it turns off the magnet which not only pops up the toast but also powers down the whole toaster. It is simple, but not too simple — as we always say, less isn’t really more; just enough is more.
In all fairness, the IC inside is little more than an integrated 555 timer. The darkness control sets the frequency (nominally 1024 Hz) and the timer asserts the output until the timer expires. Of course, this is the cheapest possible toasters. Some toasters can be quite fancy with real time timers, temperature or color sensors, and some can even print the weather forecast on your toast. You can have a peek into a more sophisticated toaster oven in this NXP application note.
Toasters of the future may have their own neurosis. You could even have a flying toaster, but we don’t know why. With your own toaster, you never have to suffer from your breakfast failing to include toast — helpful if you are lack toast intolerant.