I’m in favour of KISS. The simpler a product is, the less there is to go wrong, and the less likely it is to break. Take pop-up toasters, for instance. The early models had a lever to lower a tray into the heating region; the tray was on a spring, and a small hook held it in place while the bread cooked. A set of four contacts acted as a switch which was engaged while the tray was in place; the switch activated the heating elements. The hook was attached to a bimetallic strip whose reach could be adjusted; as it heated, it bent until it released the hook, releasing the bread holder and popping up the toast. If you decided to remove the bread before it popped itself up, you just pushed the lever up. No power was used until the lever was pushed down, and no more power was needed than to heat the elements. Very simple, and very rarely did anything go wrong.

Someone decided that that was not good enough, so they redesigned the internals to use an electronic timer (variously a 555 or one made from MOS gates) and an electromagnet to keep the tray down. The electronics had to be powered from a low-voltage DC supply, adding complexity and power consumption; because the electronics was subject to severe thermal stress, it tended to fail relatively often. Because the tray was held down by an electromagnet, power consumption was up. If you wanted to remove the bread before the timer finished, you had to push a button, though you could force the lever up. Less simple, more failure points. These failed much more often.

I’ve just been given a more recent toaster to fix. This one has no levers, but has a set of about 8 buttons, one of which activates a motor to lower and raise the tray. The whole thing’s under control of a microcontroller (!!! a dedicated computer to control a toaster!?!). This thing even connects to the internet! A toaster! As for how often they fail — well, this one’s out of warranty, so it’s more than a year old, but not much. And it’s already failed.

There’s an international competition for student engineers; the aim of the competition is to make better engineers by making them study bad engineering. Competitors have to design the most complicated machine they can for doing some very simple thing (specified by the competition organisers), a la Heath Robinson or Rube Goldberg. The year I did it the “simple thing” was to cook some toast. This toaster would have a damn good shot at winning.