WEBVTT
Kind: captions
Language: en

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One of my favorite things in life is when
I discover an unexpected piece of technology

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in everyday household items.

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Many of us have so many interesting things
around us that may go unnoticed.

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Take kitchen appliances, for example.

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They’re often a lot simpler than at first
they seem, but in at least one particular case,

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that simplicity is accomplished with
wondrous ingenuity.

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I’m talking, of course, about toasters.

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Yes, the toaster, perhaps the silliest household
appliance.

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A single-purpose receptacle in which you place
sliced carbohydrate media to be partially

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burned for your enjoyment.

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Delicious.

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Electric toasters have come a long way from
their 19th century roots--

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good grief that’s terrifying--

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wonder no more when the toast
will pop up.

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The jumpscare potential has been completely
eliminated with this digital display.

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And wanna toast more than bread?

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What about a bagel?

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Be amazed as the side elements turn off, toasting
only the cut side.

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Innovation at work!

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Of course, if you actually go back a mere
70 years in time, you’ll discover a toaster

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that is better than modern toasters in nearly
every single way.

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You’re right, sally, it is like magic.

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But ignoring the surprising backward steps
we seem to have made in the tantalizing territory

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of toaster technology, let’s get to the
point of this video, shall we?

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This toaster was a mere $8.88.

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That’s only $4.44 per slice!

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Now, perhaps it’s not surprising to you
that a toaster can be manufactured so cheaply.

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It is after all simply a small box with a
bit of nichrome wire

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(that’s an alloy of nickel and chromium)

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forming bread-singeing
heating elements.

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How complicated can it be?

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All it has to do is turn on the heating elements for a while,

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then shut them off and lift the bread.

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Ah, but see, it’s the way the simplicity
is accomplished that’s so ingenious.

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First, have you ever tried to push the lever
down while a toaster is unplugged?

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If you do, you’ll notice that it simply
won’t stay down.

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No matter how hard you force it, the lever
simply springs back up.

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Why is that?

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Well, it turns out that this single lever
is performing the roles of bread lowering

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and lifting mechanism, power button, switch
contact, retention latch, circuit breaker,

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and thing-that-moves-the-little-bread-squeezing--centering-things-in-and-out.

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Uh, to explain how it does all those things,
we’ll need to take this apart.

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And through the magic of buying two of them,
I have an already-taken-apart one right here.

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Under the plastic covering is a sheet metal
box containing the heating elements, as well

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as a small circuit board.

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This circuit board doesn’t do all that much,
but the way it has been integrated into the

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device as a whole is simply fascinating.

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First, notice these two pairs of contacts.

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These are what actually provide power to the
toaster.

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In this state, there is no completed circuit.

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If you look at where the power comes in on
the board, it goes right to this contact,

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and then it’s got nowhere to go.

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This contact must be pushed down to complete
the circuit.

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Actually both pairs of contacts must be, as
the other one breaks the connection on the

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neutral side as well, a smart move to protect
against the potential for a power outlet with

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the hot and neutral wires reversed.

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If, when it’s plugged in, I manually engage
the contacts using these

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high-tech insulated poking devices, now power can flow through the toaster.

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You’ll hear a slight buzz and see that the
heating elements begin to glow.

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[buzzing of toaster]

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Not only do the elements
receive power, but so does the rest of the board.

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But what is responsible for normally engaging
those contacts?

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Why, the lever of course.

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Also, I’ve just realized this isn’t technically
a lever.

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Why do we call it a lever?

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Wait, do we call it a lever?

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Let’s double-check that Sunbeam ad.

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Yeah, lever.

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Hmm.

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Anyway when the lever reaches the bottom,
a set of its own insulated poking devices

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press the contacts down, and thus complete
the circuit.

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That’s not the interesting part, though,
ho no.

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The interesting part is how it stays down.

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Remember, with the toaster unplugged, the
lever refuses to stay in the down position.

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It just pops right back up.

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But with it plugged in, now it will.

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How?

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Well, watch closely.

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Did you see that metal plate suddenly stick
to the yellow thing?

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Watch again.

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That yellow thing is an electromagnet, and
so long as it has power,

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it will hold the lever in place which keeps the contacts pushed in

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and allows power to flow through the heating elements.

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Now you may have already figured out the double
whammy of genius here.

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If the only thing holding the lever down is
an electromagnet, and the only way the toaster

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will work is with the lever held down, then
by shutting off the electromagnet, it will

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let go of the spring-loaded lever, shut off
the power, and of course eject the bread,

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now toast, in a violent fashion without warning.

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Fascinating.

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Which brings us to the other stuff on the
circuit board.

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Though we don’t need much in the way of
circuitry in here, we do need a way to determine

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how long to hold down the lever, and thus
how long to toast the bread.

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These days it’s handled with specialized
components, like this

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(in a high-pitched, altered voice)
“MULTIPLE FURNACE DISABILITIES TIMING IC”,

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which features
such marvels as CMOS, TO-94, and Bagel.

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Google Translate wasn’t much help here,
but in any case we do know this is suitable

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for all types of toaster, and it appears to
support a bagel mode but I can’t see exactly

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how the chip itself is going to handle a bagel
mode given that it only has the one output.

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In any case, the main thing this chip is doing
is looking at the output from the potentiometer

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here to determine how long to stay on.

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And as we know from the datasheet, roast the
development of the time interval: 0-300 seconds.

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Also, let’s just get it out of the way that
these numbers do not correspond to minutes.

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Tom Scott already did a video on this, but
this should give you further proof because

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if the max time is 300 seconds, that’s 5
minutes, not 6, so these are just arbitrary numbers.

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And funnily enough the box suggests there
are only 6 settings, when in reality there

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are probably 300, as this is not a 6-position
switch, it is an infinitely variable potentiometer.

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But I digress.

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Anyway, most of the other stuff on the board
is support equipment for the main IC, such

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as its power regulator and smoothing capacitors,
though surprisingly there is a diode connected

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straight up to this yellow lead going into
the toaster body.

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This might be designed to halve the available
current to part of the element through half-wave

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rectification, and indeed the middle section
doesn’t glow as intensely as the outermost

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sections so perhaps that connects to the middle
section, but I can’t say for sure.

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If I’m following my traces right, the actual
electromagnet is connected to this little

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transistor on the bottom, which is itself
connected to the output of the main IC we

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were looking at earlier.

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So, the IC is in control of the electromagnet
and when it decides the toast is done, it

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kills the output to the transistor, which
kills the power to the electromagnet, which

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kills the power to the everything.

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Oh, and this little switch here, activated
by turning the darkness dial all the way to

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the left, will interrupt power to the electromagnet
and immediately release the toast.

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There’s a bit of a poetic sadness to the
way this circuit works.

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When you press the lever down, it comes to
life and says “Oh!

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Hello world!

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Let’s see, first I’ve got to send power
out on pin 1.

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It looks like I’m getting 2.4 volts in on
pin 3 so I’ll just count to 137.”

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And then 137 seconds pass and it says “Time’s
up!

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Now I’ll just stop sending power out on
pin 1 and…”

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Before we were putting self-aware digital
circuits in toasters, mindless analog circuits

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would do the same thing but more crudely.

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Often the timing was accomplished through
charging a capacitor, and the setting of the

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darkness dial, being a potentiometer, would
change the rate at which this capacitor was charged.

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Once it’s past a certain voltage level,
the power gets cut to the electromagnet via

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a transistor, and pop goes weasel.

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And before that, a simple mechanical clock
timer would suffice.

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And I haven’t even gotten into this complication;
some toasters use more than just time, or

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don’t use time at all!

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Sometimes there’s a bimetallic thermostat
near where the bread sits, and adjusting the

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darkness adjust the temperature at which the
thermostat would open the contacts.

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No timer required.

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Newer toasters with digital circuits can use
use a thermocouple to determine if the toaster

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is cold and thus if it will need more time
for the first toast, and less time for subsequent ones.

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The sky’s the limit when it comes to today’s
totally technical temperature-tied toaster technology.

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In fact, if you’re looking for something
to read, check out the description for a patent

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on time-based temperature compensation circuits
from 1982!

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This design uses a second capacitor that is
charged up fully whenever the toaster is used,

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and slowly discharges after the toaster has
finished toasting.

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If the toaster is immediately used again,
it won’t have discharged much at all.

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The charge on this secondary capacitor effectively
gets transferred into the main timing capacitor

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and thus will shorten the overall toasting
time,

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helping to compensate for an already-hot toaster.

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If it hasn’t been used in a while, the capacitor
will be fully discharged, and thus the toaster

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runs for the normal period of time.

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You may have spotted the “chip with temperature
compensation” earlier, so even our $8.88

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toasters probably have a similar hot-toaster-taming-timer.

00:09:09.110 --> 00:09:12.699
If anyone wants to look at this schematic
and reverse engineer how it could do that,

00:09:12.699 --> 00:09:17.040
be my guest, but I’ll throw my supposition
into the ring and suggest that the chip probably

00:09:17.040 --> 00:09:21.960
can stay awake for a while between toasts
thanks to energy stored in one of these capacitors,

00:09:21.960 --> 00:09:25.120
and thus can keep track of how long it’s
been between toasting sessions.

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Anywho, I think I’ve had enough toast for
one day.

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Actually, I don’t even really like toast.

00:09:29.889 --> 00:09:33.230
I haven’t used my toaster in close to a
year.

00:09:33.230 --> 00:09:37.629
In fact, I’m pretty sure the last time I
used it was to hold up the multi-colored flashlights

00:09:37.629 --> 00:09:41.040
in the “these are not pixels revisited”
video.

00:09:41.040 --> 00:09:42.040
Yikes.

00:09:42.040 --> 00:09:45.879
And of course, I’d like to raise a toast
to the wonderful people on Patreon who keep

00:09:45.880 --> 00:09:48.740
these videos and my terrible puns coming.

00:09:51.180 --> 00:09:56.060
With the support of people like you, Technology
Connections is about to see a pretty major upgrade.

00:09:56.060 --> 00:09:59.480
I’ll fill you in on the details pretty soon
but for now, if you’d like to support the

00:09:59.490 --> 00:10:03.360
channel with a pledge of your own and get
perks like early video access, occasional

00:10:03.360 --> 00:10:07.649
behind-the-scenes footage, as well as find
out what that upgrade is I’m talking about,

00:10:07.649 --> 00:10:09.610
please check out my Patreon page.

00:10:09.610 --> 00:10:12.100
Thanks for your consideration, and I’ll
see you next time!

00:10:12.660 --> 00:10:14.660
♫ toasty smooth jazz ♫

00:10:16.800 --> 00:10:21.839
And, through the magic of buying two of them,
I have an already taken apart one, right here!

00:10:21.839 --> 00:10:24.949
(cord hits the microphone) That went really
badly!

00:10:24.949 --> 00:10:27.340
Often the timing was accomplished through
charging a capacitor.

00:10:27.340 --> 00:10:28.580
[toaster pops up]

00:10:30.740 --> 00:10:33.460
So it definitely is temperature
compensated.

00:10:33.460 --> 00:10:35.160
We figured that one out.

00:10:37.340 --> 00:10:38.420
Before we were putting self...

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[toaster pops
up]

00:10:39.140 --> 00:10:40.620
(bleep) it’s that fast!

00:10:41.180 --> 00:10:45.380
Ah, but see it’s the way that simplicity
is accomplished that’s so ingenious.

00:10:45.380 --> 00:10:49.460
First, have you ever tried to push the lever
down while the heater is unp….

00:10:49.460 --> 00:10:50.480
Toaster….

00:10:50.520 --> 00:10:54.459
Often timing was accomplished through charging
a capacitor, and the setting of the darkness

00:10:54.460 --> 00:10:58.420
dial, being a potentiometer [toast pops up],
would change the rate…

00:10:58.420 --> 00:10:59.180
Yeah I shoulda known…