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Well, it’s been a minute.

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I’ve been working on a pretty complex topic,

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and in the meantime I need to think of something quick.

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If only I had more time…

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that’s it!

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How ‘bout a little taste of November in January?

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Do you have an electrical thing you want to
have turn on at a specific time every day

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and then also turn off at a specific time every day?

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I know, so do I!

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But that sounds really hard.

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I mean, we all know how to make and break
electrical connections with a switch -

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you just gotta touch the metal together and then
pull it apart real fast!

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00:00:32,605 --> 00:00:38,565
And we also have these clock things that have
an hour hand that slowly turns in a circle twice a day.

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But y’know…

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some of ‘em only rotate once a day
for those that prefer their time served that way.

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I wonder if we could connect the technology
of clocks with switches.

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Oh look, it’s a that!

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OK, like a door that’s left its frame,

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that intro was unhinged.

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I’m sure you’ve seen these things before,
they’ve been around for a long time.

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In fact, I’m not even sure how long they’ve been around.

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Thanks to that Nintendo thing all the youngin’s are playing with

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internet searches involving the word “switch” are ruined.

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Now, I found a time switch from 1921 which
automatically turns stairway lights off after three minutes,

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but that’s not what I want to talk about here.

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I want to talk about ordinary timer switches:

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the kind where you tell it an on and off time and it repeats that daily.

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I suppose this is a sufficiently obvious idea
that it got implemented in one way or another

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just as soon as we figured out the light bulb.

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All we really need is a clock that can actuate a switch.

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In theory this could be as simple as a rotary switch which gets hit
by the hand of an ordinary wind-up clock.

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When it collides with the switch,
it would turn it from off to on and back.

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To make this a little more flexible, instead of giving that clock hands

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we can use a wheel that rotates once per day.

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Then we could attach little actuators to that wheel that will hit the switch,
and there you go -

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you’ve just made a timer switch!

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Let’s take a look at this consumer-grade timer switch.

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This Intermatic Time-All was a staple of American
life - or at least some American lives -

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in the nineteen seventiesss? Probably?

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I’m having a heckuva time tracking down specific dates for this model’s introduction

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but it’s old enough that it doesn’t have a polarized plug -
which makes it borderline useless today.

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But, sure enough, it’s basically a weird-looking
24 hour clock that has a wheel instead of hands,

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and hanging around the edges of that
wheel are these little movable tabs marked “ON” and “OFF.”

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You can move them by pushing them down, and
then they’ll slide around the edge of the wheel.

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Simply put the ON time where you want it,
then the OFF time where you want it.

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00:02:53,450 --> 00:02:56,930
Of course, you also need the clock to be set to the right time.

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You set the time by turning the wheel so that
the current time lands where the “Time of Day” pointer is pointing.

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00:03:03,569 --> 00:03:09,802
Sticking out the side of the device near that
spot is a little black knob that’s also marked “ON” and “OFF.”

49
00:03:09,802 --> 00:03:13,941
That is the actual switch mechanism that the clock activates.

50
00:03:13,941 --> 00:03:20,452
And when I turn the dial by hand,
I encounter resistance once the tabs get near that knob.

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Keep turning and you’ll see that the knob starts to move.

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And right when the tab hits the “Time of Day” indicator

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*click*

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the knob snaps into the OFF position.

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Cleverly, the ON tab can only turn the switch from OFF to ON -

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if the switch is already on,
well the ON tab doesn't do anything as it passes the switch.

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00:03:42,868 --> 00:03:44,353
Same goes for the OFF tab.

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If the switch is already off, that tab won’t do anything.

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This not only prevents the timer from slipping into the inverse of what you want,

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but it also means that you can manually flip this to ON or OFF
to give a temporary override without screwing up the programming.

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The timer will resume normal timed operation
when the correct tab hits the switch once more.

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I’ll show you how that works in a moment

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00:04:07,060 --> 00:04:12,916
but I want to point out that since this really is just a clock attached to a switch,

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that clock could be powered by anything.

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It could be a wind-up mechanical clock,

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or a battery-operated clock,

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or even gravity driven with chains if you were particularly eccentric.

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But as this thing's gonna get plugged into a wall outlet since...

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that’s its whole thing, 
the clock mechanism is driven by a synchronous motor.

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That's a special kind of motor that spins
in lock-step with the frequency of incoming AC power.

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Since grid operators do a fine job of making
sure that power runs at exactly the right frequency,

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and will even make adjustments day-by-day to account accidental for drift,

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it serves as a reliable basis for keeping track of the time.

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At least, usually.

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Since the AC line voltage here runs at 60 Hz,
that means the motor will spin at 3600 RPM (assuming it’s a single pole motor).

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That’s, of course, way too fast so a ton of gear reduction
is used to slow it down to

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.00069 (nice) RPM or 1 RPD -

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revolutions per day.

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Anyway, here’s where the actual switching
and the timing of that comes into play.

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First let’s talk about the electrical switch that makes this thing useful.

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In this timer it’s almost hilariously crude.

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Incoming power from the blades runs right
to the terminals of the outgoing receptacle, and -

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woah.

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Hang on, those terminals?

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They’ve got bumps on them which actually engage with the holes in a plug!

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Finally we found something!

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No surprise it’s old.

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Anyway, one blade has a simple wire link
attaching it directly to the incoming power,

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and the other runs through two formed pieces of brass
that touch through a contact right here.

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The pokey-outey knob of the power switch attaches
to a shaft running through the timer body,

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on the other end of which is a simple rectangular
bit of plastic which either pushes the contacts apart or lets them the touch.

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A simple 90-degree turn of that shaft is all that’s needed to change switch states.

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As discussed previously on this channel,

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electrical switches should have a snap-action
to prevent arcing from damaging the contacts.

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Here that’s accomplished with a simple arrangement
of two pieces of metal which act like leaf springs.

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They surround a square cross-section of the switch shaft,

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keeping a slight amount of pressure on it and holding it in-place.

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As the shaft is turned, the corners of the square 
start to distend the leaf springs by an increasing amount -

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thus increasing the force required to turn the switch.

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But once the square is just past the 45 degree
mark into a turn, the springs will now help turn the switch

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00:07:01,547 --> 00:07:04,895
and it quickly snaps into the next position.

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This design relies on the timer’s plastic
shell to hold the top half of the spring in-place,

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as well as to put pressure right on this spot
of the brass link to make the contacts actually touch.

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So then, here’s how the automatic switching happens.

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There’s more going on with those sliding
tabs than you can see from above.

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As the dial turns with the passage of time,

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the ON and OFF tabs slowly approach the switch knob.

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00:07:31,610 --> 00:07:36,886
The OFF tab has a protrusion that will collide
with this wing on the switch shaft -

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time marches on, though, so the tab will slowly rotate the switch.

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And once it’s pushed it far enough, the switch snaps into the next position,
opening the switch contact.

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Notice that there are only two wings on the shaft - now that it’s in the OFF position,

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the OFF tab on the timer’s wheel can no
longer change the timer’s state.

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The wings are parallel to the wheel and at this point are useless.

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Further into the timer, though, we find another
pair of wings on the switch shaft -

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a pair in the opposite orientation as the first.

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The timer’s ON tab has a protrusion just like the OFF tab,

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but it’s positioned inward so it can only collide with this second wing.

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Once it does, of course, it pushes the wing forward,

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turning the shaft, and eventually it clicks over into the ON state.

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This staggered arrangement is how the manual
override can work without screwing up the timer settings -

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the ON tab can only ever turn the timer on,
and the OFF tab can only ever turn the timer off.

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If it’s already in the same state as the tab would turn it to,

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the tab has nothing to grab hold of.

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This design also allows you to pull the switch knob out slightly,

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which takes those tabs entirely out of alignment with the switch,

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thus turning this into a manually-operated switch
until you push the knob back in.

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A nice feature, I suppose.

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While this design works and works well,

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it’s also somewhat limited.

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You can only pick a single on and off time,
and the shortest duration you can have between them is two and half hours.

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To alleviate these limitations, eventually Intermatic would change this design
from sliding tabs to removable tabs.

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This timer here is one such example.

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The overall method of operation is remarkably similar to the first timer.

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We have a rotary switch, though now it’s up here,

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and the on and off tabs simply push that switch into the next position
when they collide with it.

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00:09:40,970 --> 00:09:45,030
The green tab turns it on, and the red tab turns it off.

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00:09:45,030 --> 00:09:50,339
The two tabs have their switch actuator pokey bits
at different depths so, just as before,

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the on tab can only turn it on and vice versa.

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00:09:54,180 --> 00:09:56,413
The similarities don’t stop there, though.

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Internally we have a remarkably similar motor and gear reduction drive,

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and the switch itself is still quite crude.

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It’s also damaged on this one because

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SOMEBODY decided they should hide a screw underneath the clock dial

144
00:10:10,886 --> 00:10:15,490
and I didn’t figure that out until AFTER I went ham with a screwdriver and pliers.

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00:10:15,490 --> 00:10:18,748
Anyway, this time they’ve refined the switch

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by making the switch blades double as the springs
which provide that nice snap-action.

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00:10:24,399 --> 00:10:27,130
But otherwise it’s still just as crude -

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are these wires even soldered to the motor leads?

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00:10:30,681 --> 00:10:35,048
Oh but this time they did at least take care to switch the hot leg.

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00:10:35,048 --> 00:10:41,545
In the old timer, if you installed it upright
on the most-common outlet orientation you’ll find here,

151
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the switch broke the neutral.

152
00:10:43,403 --> 00:10:45,179
Very good.

153
00:10:45,179 --> 00:10:47,702
I mean it wasn’t polarized anyway but still.

154
00:10:48,000 --> 00:10:55,030
Anyway, since you actually remove and replace
these tabs on this design to set the on and off times,

155
00:10:55,030 --> 00:10:58,740
you can add more if you want a more complex program.

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00:10:58,740 --> 00:11:03,273
When new these timers came with two or maybe three pairs of tabs,

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but tabs are very easy to lose and unfortunately Intermatic didn’t think of designing some sort of tab-holder into this to store them.

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You’d think this might be for that purpose but nope, they don’t fit there,

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so those extra tabs tended to disappear.

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Don’t worry, they sell replacements!

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Actually as a matter of fact you can still buy this timer new,

162
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though stock appears to be dwindling.

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00:11:30,286 --> 00:11:35,404
Also, you can indeed put the tabs right next
to each other and the timer will work -

164
00:11:35,404 --> 00:11:40,896
so if you want something to be on for just a half-hour,
well now you can do just that!

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00:11:40,896 --> 00:11:43,637
Luckily, at some point somebody asked

166
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“why are we faffing with those tabs?” 
and designed a timer like this one.

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00:11:48,243 --> 00:11:55,538
Now, the face of the timer has 48 individuals tabs along its perimeter which can be up or down.

168
00:11:55,538 --> 00:12:03,726
Annoyingly these things almost never bother with printing
“up is off, down is on” so it’s always a game of trial and error setting one up,

169
00:12:03,726 --> 00:12:08,764
but once you figure it out you’ve got all the flexibility this design
could ever offer,

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and without the risk of losing the tabs
since they’re now permanently attached to the timer.

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00:12:14,520 --> 00:12:22,253
Internally, we still have a synchronous motor and gear reduction
making the dial rotate once per day by way of this drive gear,

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but now we have an off-the-shelf microswitch doing the switching with micro flair.

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00:12:27,959 --> 00:12:32,412
A simple lever connects the switch’s actuator
to the perimeter of the dial.

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00:12:32,412 --> 00:12:39,430
In this design, the dial acts as a very slowly
turning cam which that lever rides against.

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00:12:39,430 --> 00:12:41,309
When the tabs are in the down position,

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they push on that lever which depresses the switch actuator allowing power to flow.

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00:12:46,430 --> 00:12:52,079
However, when they’re in the up position
they leave space for the lever to fall into,

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and that releases the switch, opening the contact.

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00:12:55,501 --> 00:13:00,798
Microswitches have their own internal spring
mechanism to make the switch action happen quickly;

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00:13:00,798 --> 00:13:03,458
you can hear it clicking when I depress it manually.

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00:13:03,458 --> 00:13:05,209
*clicky clicky clicky click*

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00:13:05,209 --> 00:13:08,273
And since it always wants to push that actuator out,

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the switch will in effect turn itself off as soon as the lever falls into the cam
thanks to a pulled-up tab.

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00:13:15,239 --> 00:13:20,352
This design also allows for a simple slider
to provide a program override -

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slide this over and now the switch is pressed in
regardless of the tab situation.

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00:13:25,698 --> 00:13:30,137
However, it won’t automatically resume the program like the Intermatic timers will.

187
00:13:30,137 --> 00:13:34,848
It will only return to the program when you switch it back to timed operation.

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00:13:34,848 --> 00:13:38,371
Now, in case you haven't realized, it's 2023.

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These days we have more phosticated ways of
timing when things can and cannot get power.

190
00:13:43,746 --> 00:13:47,966
But mechanical timers like these still have their applications.

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00:13:47,966 --> 00:13:52,068
I whip out a few during Christmas time for
some indoor lighting displays.

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And it can be nice to set up, say, a floor lamp on a timer like this to give you some light when you get back from a day out and about.

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It may be basic, but it’s still automation.

194
00:14:02,866 --> 00:14:09,693
And in the commercial realm, you still see similar timers used for things like defrost cycles in refrigeration equipment,

195
00:14:09,693 --> 00:14:13,050
lighting signage so it goes out after closing time,

196
00:14:13,050 --> 00:14:16,220
or even just exterior lighting in general.

197
00:14:16,220 --> 00:14:21,691
Though photocells are usually a better option
since the sun does that thing where the days get longer and shorter.

198
00:14:21,691 --> 00:14:24,420
But as electronicals get cheaper and cheaper,

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00:14:24,420 --> 00:14:30,930
well now it’s just as likely that when you need a basic timer 
you’ll be getting something like this.

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00:14:30,930 --> 00:14:34,947
A microcontroller hooked up to a display,
some buttons, and a relay

201
00:14:34,947 --> 00:14:37,503
makes for a very flexible timer.

202
00:14:37,503 --> 00:14:40,440
Want different programs for weekdays and weekends?

203
00:14:40,440 --> 00:14:42,019
Knock yourself out.

204
00:14:42,019 --> 00:14:44,410
Concerned about the time drifting with a power outage?

205
00:14:44,410 --> 00:14:50,040
Well, just stick a little rechargeable cell on the board
and use a clock crystal as your time base.

206
00:14:50,040 --> 00:14:55,144
You can even get inexpensive timers which,
after telling them where you are on the planet and the date,

207
00:14:55,144 --> 00:14:58,793
will automatically adjust sunrise and sunset times throughout the year

208
00:14:58,793 --> 00:15:02,135
all without needing WiFi or an app.

209
00:15:02,135 --> 00:15:03,762
And that’s pretty neat.

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00:15:03,762 --> 00:15:09,864
Still though, I can’t help but admire the
charm that is a clock which turns a switch.

211
00:15:09,864 --> 00:15:12,878
Or, I guess, presses a button in some cases.

212
00:15:12,878 --> 00:15:15,926
Take two basic things, smoosh them together,

213
00:15:15,926 --> 00:15:19,004
and you can make a pretty handy new third thing!

214
00:15:19,004 --> 00:15:23,020
Do it well enough, and you can even change the world.

215
00:15:23,020 --> 00:15:26,843
Thanks to Mike for sending these timers my way way back when when,

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and of course thanks for watching.

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♫ regularly-scheduled smooth jazz ♫

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I’ve been working on a pretty complex tompic…. Tompic?

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Awwwghh

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That’s it!

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How ‘bout a taste of little November [laughs]

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I mean, we all know how to make and break electrictcalkiconnec

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I suppose this is a sufficiently obvious idea that it got incorp --

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Dahh, I could’ve made that work.

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I suppose this is a sufficiently obvious idea that…

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it got implemented in one way or another…

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just as soon as we figured out the light bulb.

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Why is the pacing so wrong?

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*click*

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the knob snaps into the off position.

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Except I just turned it on.

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One blade has a simple wire link attaching
it from the from the from the from thing.

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Internally we…

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good god!

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So, it was just about time for this video, eh?

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Do you think when doing inventory, after discovering a lack of certain herbs, 
a chef will yell

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"we're running out of thyme!"?

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I mean, if I worked as a chef, you can bet your bottom dollar that I would.

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Every thyme.