The Surprising Tech Of A Cheap Toaster

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.

62 thoughts on “The Surprising Tech Of A Cheap Toaster

      1. Toasters can be quite complex to design properly. I remember a lecture on robust design engineering and an example of statistical Taguchi method being applied to a toaster to reveal the critical design variables and their best combination that would result in the most uniform toast that wasn’t sensitive to manufacturing variabilities.

        Couldn’t find that particular case, but this seemed interesting as well and goes to the earlier phases in product development and defining product architecture.

  1. It sounds like an upscale toaster The last cheepie I took apart for the nichrome wire was all mechanical as far is it’s mechanism went. No IC’s and no electromagnets. Just a simple bimetallic thermostat type device that released a catch so springs could pop the toast up and cut the power to the heater. This new toaster seems like it is putting a lot of electronics where it is not needed and there is more to go catastrophically wrong.

    1. I was thinking to note the same thermomechanical and thermoelectric components from older toasters since they can be salvaged and re-purposed into other projects designs. Interesting seeing the integration of components into a toaster… that can be hacked easier maybe? Wondering what the RINT (like RF/EM) profile is like?

      1. Years ago I reused the mechanical timer from a toaster from scrap for my PCB exposure lamp. It hat a kind of clockwork with an escape mechanism, but no timing spring. The part of the escape which controlled the motion of the wheel just “bounced back and forth” by it’s inertia between some kind of end-stops. Precise enough for a toaster.

        1. Wolf is the label for high-end kitchen appliances that heat (better known for pro-sumer ranges), you might be more familiar with the manufacturer’s label for cold appliances: Sub-Zero.

    2. I used to design electric grills, both electrmechanical and all digital. The cost difference between the 2 is a lot smaller than most people would guess. It all comes down to the fact that electromechanical systems require more physical material, tighter (not a lot, but every penny counts) manufacturing tolerances, and more man hours than electronic controls. The digital controls typically require more R&D cost, but the ICs are so damn cheap, and the PCBA mfg is highly automated such that it offsets the cost of using digital circuitry. Also, the cost of line setup is getting cheaper for the digital controllers because the factory line can be switched to a new product with fewer tooling changes and lower down time.

    1. My old one had a CD4060 and a CD4011. It failed to pop the toast out and I tracked it down to a failed CD4011. A cheap, but not lasting repair. The electronics were supplied by a tap of the heating coil – like a voltage divider. And an intermittent connection at the neutral (“GND”) side caused mains voltage spikes to the electronics.

  2. My toaster drives me crazy. It beeps *before* it pops up. Probably, popping up opens the circuit so there’s no power flowing at all. Thus, it it’s going to beep, it has to beep before it’s done.

    It bugs me because it’s not the way I would’ve designed it. Why do toasters need to beep anyway? The pop-up sound is classic and unmistakable. The beep just sounds like everything else in the house that beeps.

    1. Yea a simple beep is kinda lame.

      My design would involve an eink screen on the side to display a small Link with arms stretched above his head, and a wav sound IC to play the classic zelda ‘item get’ sound.
      If it is going to add everything to make a beep yet doesn’t go this far, it’s just halfassing it in my book.

    2. It’s anti-startle beep. You know, I’ve been startled many times by my toaster and that beep would actually help, especially when still being sleepy and starting morning toasts, then going to make morning coffee.

          1. And every time you hit “snooze” and a new time has to be burnt, it moves the toast up one line? Like printer paper. Including an “out-of-toast” alarm.
            But how to burn the time? A “daisy wheel” with nixie-electrode like numbers from NiCr wire? Or a laser scanner? A 5W diode laser with slow scanning could probably do it.

    3. I had to repair my microwave with with a plier to rip out it’s buzzer.
      The bloody thing kept beeping every 30 seconds after it was finished.
      One baked a cake in it and went shopping. Wen I came home a few hours later the thing was still beeping.

      My microwave won’t ever beep a nobody again nomore.

      1. OMG, your popcorn is done. YOUR POPCORN IS DONE! It’s done! Come get your popcorn! Your popcorn is ready! Come get your popcorn! It’s done! Your popcorn is getting cold! Delicious popcorn, ready to eat! Popcorn! Get your popcorn, here! Is anyone out there? What, do you hate popcorn? Popcorn, get it while it’s hot!

        [Actually, my current rage against my microwave is that the “buttons” have zero physical feedback, so I often find myself having to place full focus on the pad to actually depress anything, and watch the screen to know it received. Sometimes I detest the future.]

        1. The screen on our microwave prints out “Enjoy your meal” when it stops cooking.
          I feel slightly insulted when I just used it to sterilize a kitchen sponge or heat up a rice bag for sore muscles.

  3. I like my old late 60’s or early 70’s pop up toaster oven. Has a vertical slide on the right for toast color, a vertical slide on the left for oven temperature. There’s a small “Color Tuner” vertical slide on the right rear. There’s one slot on top for two slices of bread side by side. The bar to push down to activate toasting is on the right side.

    The door in front has a glass window, tips down and partially slides out a wire rack. Heating is via four horizontal quartz tubes with coiled (tungsten?) elements inside.

    Operation is entirely electro-mechanical. I assume there’s a bi-metallic device that trips a catch to release the bread basket and cut off the power. Attempting to toast again too soon results in a faster release and less toasty toast.

    For oven use, temperature is controlled by some thermostatic switch that pulses the heater rods on and off, with much heat flowing out the open top slot. Despite that it does a good job baking biscuits.

    A few years ago it would no longer latch down to toast, it’d just make a loud buzzing sound. Apparently near 40 years of almost daily use had caught up with it. So I took it apart. Seeing nothing obviously bent or broken, I put the dismantled device (aside from the heater rods, I didn’t want water in them) in my dishwasher and ran it through a cycle, without the heated dry.

    After letting it open air dry for a day I put it back together and it worked perfectly! I think there may have been some silicone grease on some of the sliding parts to dampen the motion because since getting its bath it sometimes ejects the toast completely, where it flaps down flat atop the toaster.

    Good for another 40 or more years! Nobody builds small kitchen appliances like that anymore.

    1. Totally Twisted After Dark: My favorite screensaver of all time, though it was a bit unstable under Windows 3.11 on my old 386-33. I really hope someone brings that app back some day…

  4. 2019 and still no roast shade controlled toaster: when unfreezing slices of bread, I still have to figure out the correct toasting time.
    BTW, also waiting for the smoke detection integrated!

    1. Simple (temperature shielded, somehow) color sensor and you’re in business! Maybe a mirror? And some reliable illumination? Can you get away with just sensing the amount of reflected red? There is science to be done here!

      First person to implement this gets a Hackaday article, and Internet Fame.

      (Internet Fame and $3.27 will get you a two-pump vanilla latte at Starbickers.)

  5. Forgot to mention where yellow wire comes from . It normally comes from a tapping on one of the heating elements so the element is a big voltage divider . common fault as when connection point fails after a crumb has lodged there , no power to board.

  6. The electro-mechanical timer using the bi-metal strip has served well for many decades and its a shame to see such a reliable system go. My Swan toaster must be 35-40 years old but today I spent the afternoon dismantling it as it​ had stopped working. ​I discovered the part of the toaster that has failed is the electro-mechanical timer​​. It consists of a coil​ of wire​ on a mica former wrapped around a strip of brass and steel and the coil had gone open circuit. I was fascinated how it timed the toast so investigated…

    When the toasting lever is pushed down, ​it cannot come up again as it is latched ​under one end of the brass/steel bi-metal strip. At same time electricity is applied to the toasting element and also the coil of wire wrapped around the brass/steel strip.This heats up the brass and steel ​and as they ​are firmly riveted together it slowly bends. Eventually the brass strip bends far enough to release the main ​toasting ​lever and lets it move up, but only lets it move up a fraction of an inch as it cant get past a part of the mechanism due to the way the brass strip has bent. This is the point we hear the familiar click from electro-mechanical toasters. This tiny movement of the toasting lever operates contacts that disconnect the coil heating the the bi-metal strip and it starts to cool down. This makes it bend in opposite direction and fully releases the toasting lever mechanism which then pops up the toast and disconnects the main toasting element. I always wondered why old toasters do that little click a few moments before the toast pops up and this is the reason. Its the moment when the brass bar starts to cool down and we know its time to open the butter as our toast is about to pop up. Its very clever and all works on what seems a hair trigger, but very ingenious and not an electronic component in sight.

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