WEBVTT
Kind: captions
Language: en

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In the modern world, when we want to make
something happen automatically,

00:00:04.060 --> 00:00:07.010
we use these newfangled computer things.

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Whether that means a huge industrial automation
system controlling robots in a factory, or

00:00:12.331 --> 00:00:15.080
an Arduino you learned how to program to do…

00:00:15.080 --> 00:00:17.880
whatever the kids do with Arduinos these days...

00:00:17.880 --> 00:00:22.220
our modern world is based on bits of silicon
executing instructions.

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It’s a pretty great place to be

00:00:24.120 --> 00:00:25.420
- for now -

00:00:25.420 --> 00:00:28.660
but to me it’s not all that interesting.

00:00:28.660 --> 00:00:33.800
What is much more interesting to me is the
wild world of electromechanical wonders that is...

00:00:33.800 --> 00:00:39.340
pretty much all general-purpose automation
from 1975-ish and before.

00:00:39.340 --> 00:00:42.980
Electromechanics is my favorite kind of automation.

00:00:42.980 --> 00:00:43.800
Why?

00:00:43.800 --> 00:00:48.440
Because using nothing but switches, some motors,
some relays, maybe a solenoid or two,

00:00:48.440 --> 00:00:53.380
and a heckuva lot of ingenuity, you can make surprisingly complex things happen,

00:00:53.380 --> 00:00:56.320
all without a single bit of code.

00:00:56.320 --> 00:00:58.640
For example, a jukebox!

00:00:58.640 --> 00:01:01.820
This here is the Statesman, by Wurlitzer.

00:01:01.820 --> 00:01:05.360
This beautifully brown beast hails from the
year 1970.

00:01:05.700 --> 00:01:08.310
I mean of course it does.

00:01:08.310 --> 00:01:12.010
This may be the ugliest jukebox ever produced.

00:01:12.010 --> 00:01:16.909
It’s… even as an outspoken fan of the
color brown, this is not very attractive.

00:01:16.909 --> 00:01:17.680
But!

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At least with the lights on we get some purple!

00:01:20.540 --> 00:01:26.660
Also known as the 3400 series, this jukebox introduced the new Wurlamatic record changer mechanism.

00:01:26.660 --> 00:01:30.980
Which, sadly, was a radical departure from
Wurlitzer’s previous designs which put the

00:01:30.980 --> 00:01:33.180
mechanism on full-display.

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Here it’s hidden, but luckily I have the
key to open it up.

00:01:37.329 --> 00:01:40.920
Now what this mechanism does is fairly obvious
upon a short glance.

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I mean, it’s got a carousel of records,
an arm to grab hold of one of them and place it on

00:01:45.480 --> 00:01:50.520
this little turntable, and so obviously the
carousel will rotate to a specific record,

00:01:50.520 --> 00:01:55.659
stop, the arm will grab it, put it on the
turntable with the selected side facing up,

00:01:55.659 --> 00:01:59.469
let go of it, then the tone arm will move
into position to play it, and once it’s

00:01:59.469 --> 00:02:03.450
done the tone arm will return to its resting
position, the record-grabby arm will grab

00:02:03.450 --> 00:02:05.810
it again, put it back, and we’re done.

00:02:05.810 --> 00:02:08.000
So, let’s see how that works in action.

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I’ll be selecting M3 which will play the
A side of the green record.

00:02:12.720 --> 00:02:15.100
Pay attention to the sounds it makes.

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[two clicks as buttons are pressed]

00:02:18.400 --> 00:02:20.100
[a whirring mechanical sound]

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[a clunk and a loud buzzing as the carousel moves]

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[another clunk, whirring]

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[two clicks]

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[another click]

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[whirring stops]

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♫

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Alright, and now that the record is over,
watch what happens.

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[a click, followed by the whirring again]

00:02:47.700 --> 00:02:50.040
[various mechanical sounds as the record is put back]

00:02:50.040 --> 00:02:51.660
[carousel buzzes as it moves]

00:02:53.200 --> 00:02:56.960
You might think that the carousel will stop
once it gets back to its starting position

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[faint double-click]
but it actually continues for one more rotation.

00:03:00.330 --> 00:03:01.760
Then, it comes to a halt.

00:03:01.760 --> 00:03:02.950
[clunk, and buzzing stops]

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Now you might ask, how does it know what record
to play?

00:03:06.980 --> 00:03:10.420
What was the point of that sound before the
carousel started to move?

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[button being pressed; whirring]

00:03:12.500 --> 00:03:13.830
[buzzing of carousel]

00:03:13.830 --> 00:03:17.410
And more generally, what are the brains of
this operation?

00:03:17.410 --> 00:03:22.630
If there isn’t a microcontroller controlling
things all micro-like, how can it be controlled?

00:03:22.630 --> 00:03:26.100
The answer is a whole bunch of weird, purpose-built
mechanisms,

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rats nests of wires,

00:03:28.000 --> 00:03:30.060
and a staggering number of switches.

00:03:30.060 --> 00:03:31.280
That’s it.

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Electromechanics are really quite simple as
a concept, but the applications can be a little complex

00:03:37.460 --> 00:03:39.320
at least on the surface.

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Before we get too far into the electro-side
of things,

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let’s look at the mechanics more closely.

00:03:44.710 --> 00:03:47.950
The heart of the Wurlamatic mechanism is right
here.

00:03:47.950 --> 00:03:52.880
This controls everything the jukebox does
aside from record selection.

00:03:52.880 --> 00:03:58.650
And all of its functions are performed by
a simple electric motor and a gear reduction drive.

00:03:58.650 --> 00:04:01.810
Here, I’ve re-wired the motor to a constant
power source.

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You’ll notice that it simply repeats the
same actions over and over again.

00:04:06.580 --> 00:04:07.420
Grab the record.

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Put it down.

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Move the tone-arm.

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Then the same thing in reverse.

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It’s just a constant back and forth.

00:04:13.300 --> 00:04:15.930
But notice how much it’s actually doing.

00:04:15.930 --> 00:04:20.900
It may look like it’s just moving the arm
back and forth but it’s a lot more than that.

00:04:20.900 --> 00:04:26.960
Most of everything that’s happening is happening
because of this one very complex mechanism.

00:04:26.960 --> 00:04:30.800
The mechanism is powered by the main cam
motor underneath it,

00:04:30.800 --> 00:04:34.250
and as the mechanism rotates, so do a series of cams.

00:04:34.250 --> 00:04:38.970
A cam is a sort of oddly-shaped wheel that
rotates around a shaft, and thanks to its

00:04:38.970 --> 00:04:43.890
odd shape, it translates rotational movement
into linear movement with the help of a cam

00:04:43.890 --> 00:04:47.350
follower which gets pushed as the cam rubs
against it.

00:04:47.350 --> 00:04:53.240
In fact built into the drive gear is a vaguely-heart-shaped
groove which serves as the cam that operates

00:04:53.240 --> 00:04:54.240
the record arm.

00:04:54.240 --> 00:04:58.681
It’s a little hard to see, but there’s
a little peg riding in this groove, and it

00:04:58.681 --> 00:05:03.090
causes the record arm to pivot backwards,
away from the record carousel with the help

00:05:03.090 --> 00:05:05.580
of this little ratchet and gear thing.

00:05:05.580 --> 00:05:11.680
At its pivot point, these three gears serve as the means by which each side of the record is selected.

00:05:11.680 --> 00:05:17.120
Pins on the two side gears will stop either
one of them from turning when they hit these catches.

00:05:17.120 --> 00:05:21.840
This then causes the arm to rotate sideways
as it continues to pivot backwards.

00:05:21.840 --> 00:05:26.440
Depending on which pin is stopped, it will
rotate in either one direction or the other,

00:05:26.440 --> 00:05:30.930
and this solenoid moves the catch points back
and forth, therefore its position determines

00:05:30.930 --> 00:05:32.790
which side is played.

00:05:32.790 --> 00:05:37.810
In its resting state, it will rotate to play
side B by default, and when the solenoid

00:05:37.810 --> 00:05:41.640
is energized, it catches the other pin to
play side A.

00:05:41.640 --> 00:05:46.740
Obviously the most noticeable thing this mechanism
does is move the record take-out arm,

00:05:46.740 --> 00:05:48.790
which is its official name, by the way.

00:05:48.790 --> 00:05:53.570
But thanks to a series of other cams adjacent
to the main drive gear, and the various linkages

00:05:53.570 --> 00:05:57.060
they attach to, it does much more, too.

00:05:57.060 --> 00:06:01.940
The single cam in front of the main drive
gear releases the record from the arm by way

00:06:01.940 --> 00:06:06.870
of this linkage, which also pulls the turntable
slightly to the left so the record can spin

00:06:06.870 --> 00:06:08.420
freely of the arm.

00:06:08.420 --> 00:06:13.100
Two of the cams behind the drive gear move
the tone arm to play the record, with one

00:06:13.100 --> 00:06:17.110
responsible for lifting it up and the other
for moving it left and right, and there’s

00:06:17.110 --> 00:06:21.760
even a cam just for activating this little
button which switches the amplifier from its

00:06:21.760 --> 00:06:26.310
auxiliary input to the phonograph input when
a record is being played.

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Take a look at this exploded diagram.

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This is everything going on inside the Wurlamatic
mechanism.

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There are 7 cams in total, though that’s
not perfectly true as you’ll see later.

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But anyway, these seven cams are the programming
of the physical actions that take place.

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Their shape and position dictate at what points
in the mechanism’s 360 degree rotation

00:06:48.480 --> 00:06:50.690
each action will occur.

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This may not look like a program, but it very
much is.

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Note that the cams could be made to cause one
action to happen multiple times per cycle,

00:06:59.430 --> 00:07:00.630
if required.

00:07:00.630 --> 00:07:06.360
However, this clever mechanical program doesn't
make for a useful jukebox all by itself.

00:07:06.360 --> 00:07:11.380
If it just runs all the time, well then that
wouldn’t do anything but make a bizarre

00:07:11.380 --> 00:07:13.420
record flinging dance.

00:07:13.420 --> 00:07:16.780
We need a way to control when the program
starts.

00:07:16.780 --> 00:07:20.910
Of course we also need to pause the program
in the middle when the arm has reached the

00:07:20.910 --> 00:07:24.100
turntable so the record can actually play.

00:07:24.100 --> 00:07:27.320
And then we'll need to restart the program to
put the record back.

00:07:27.320 --> 00:07:33.360
Of course, finally there needs to be a way to shut down
that program altogether once that task is complete.

00:07:33.360 --> 00:07:36.560
So we need some sort of additional control.

00:07:36.570 --> 00:07:42.200
Of course, before I re-wired the motor, it
didn’t start moving until the correct record was in place,

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and it was automatically stopping
in both the record playback and its resting positions.

00:07:46.990 --> 00:07:48.660
How did it do that?

00:07:48.660 --> 00:07:53.600
Well, what makes it automatic is the plethora
of micro-switches you see all over the place

00:07:53.600 --> 00:08:00.300
that function as interlocks, interrupts, start-stop
points, and triggers for other ancillary actions.

00:08:00.300 --> 00:08:03.700
OK, so here’s something that’s super common in electromechanics

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and is gonna come up a few times here.

00:08:06.060 --> 00:08:09.100
Self-latching circuits with interrupts.

00:08:09.100 --> 00:08:13.900
Using a relay, we can design a circuit that
will latch itself in a closed state

00:08:13.900 --> 00:08:16.610
until another action occurs.

00:08:16.610 --> 00:08:17.610
What is a relay?

00:08:17.610 --> 00:08:20.510
Well, a relay is an electrically operated
switch.

00:08:20.510 --> 00:08:25.920
A small electromagnet within the relay opens
or closes any number of switch contacts.

00:08:25.920 --> 00:08:31.100
One of the most common things we do with relays
is control high power devices with low voltage,

00:08:31.100 --> 00:08:33.080
low current control circuitry.

00:08:33.080 --> 00:08:36.420
But we can also be almost endlessly clever
with them.

00:08:36.430 --> 00:08:41.950
So, let’s say we want to turn on this light
bulb with a momentary pushbutton switch.

00:08:41.950 --> 00:08:45.960
We could wire the bulb right to the pushbutton,
but of course that means it’s only lit

00:08:45.960 --> 00:08:48.120
so long as the button is held in.

00:08:48.120 --> 00:08:51.820
And it also means the button has to handle
all of that current.

00:08:51.820 --> 00:08:56.480
What I want is for the button to turn the
light bulb on, and for it to stay on

00:08:56.480 --> 00:08:58.250
after the button is released.

00:08:58.250 --> 00:09:02.800
Here’s a simple circuit which will accomplish
that by latching itself closed.

00:09:02.800 --> 00:09:06.760
12 volts DC power is used here on the control
side of the relay,

00:09:06.760 --> 00:09:10.640
but the load side of the relay can be whatever we want it to be.

00:09:10.650 --> 00:09:15.440
This relay is now the switch which turns the
light bulb on, and it will do so whenever

00:09:15.440 --> 00:09:18.210
the relay receives 12 volts DC power.

00:09:18.210 --> 00:09:24.580
So, we’ve got a 12 volt supply and a ground for the relay, with the bulb wired on a completely separate

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120V circuit through one of the normally
open contacts of the relay.

00:09:29.740 --> 00:09:35.080
If I wire the 12 volt supply through the pushbuton,
now the relay will energize whenever the button

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is depressed, which closes the switch contacts
inside the relay, and turns on the light.

00:09:40.890 --> 00:09:45.290
This also has the benefit of making the button’s
electrical connections safe to touch, since

00:09:45.290 --> 00:09:47.920
they’re now just handling 12 volts.

00:09:47.920 --> 00:09:52.550
But, the light still goes out as soon as you
release the button because the relay loses

00:09:52.550 --> 00:09:54.400
its 12v power source.

00:09:54.400 --> 00:10:00.540
However, if I branch off the 12 volt supply to another of the normally open switch contacts of the relay,

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then feed the other side of
that back into the control side input,

00:10:04.960 --> 00:10:11.810
what now happens is that as soon as I push the
button, the 12 volt control side becomes self-powered.

00:10:11.810 --> 00:10:17.850
The button is now completely out of the picture,
as it becomes bypassed by the relay itself.

00:10:17.850 --> 00:10:22.400
The relay is now stuck in the closed position,
or latched… forever.

00:10:22.400 --> 00:10:25.160
At least, until the power supply is cut.

00:10:25.160 --> 00:10:30.580
Taking a closer look, we now have a second
power source coming from before the switch.

00:10:30.580 --> 00:10:32.920
This has 12 volts on it at all times.

00:10:32.920 --> 00:10:38.210
Again, it’s going to the second set of switch
contacts of the relay, and its output is being

00:10:38.210 --> 00:10:40.580
fed back to the control side.

00:10:40.580 --> 00:10:44.140
If there’s no power from the button, well nothing
happens.

00:10:44.140 --> 00:10:48.840
But as soon as the button supplies power,
that second wire snaps into action,

00:10:48.840 --> 00:10:51.900
bypassing the button, and keeping the relay energized.

00:10:51.900 --> 00:10:57.220
But, if I cut that second wire feeding the
relay and put a second button across it,

00:10:57.220 --> 00:11:03.130
this one with normally closed contacts, that means I
can interrupt the 12v supply that’s keeping

00:11:03.130 --> 00:11:06.420
the relay energized in order to deactivate it.

00:11:06.420 --> 00:11:09.960
Now, I press the “on” button, which energizes
the relay.

00:11:09.960 --> 00:11:14.100
This of course turns on the light bulb, but
also creates that new 12-volt supply for the relay

00:11:14.100 --> 00:11:19.870
to stay on indefinitely, but that new supply
now travels through this second button.

00:11:19.870 --> 00:11:25.830
When I press it, it momentarily breaks the
12-volt supply to the relay, which de-energizes it,

00:11:25.830 --> 00:11:27.120
and the light goes out.

00:11:27.120 --> 00:11:32.660
However, as soon as the green button supplies
12 volts again, even for just a tiny fraction of a second,

00:11:32.660 --> 00:11:37.590
the relay provides a bypass
for itself once more, and the light stays on.

00:11:37.590 --> 00:11:39.029
Pretty clever, huh?

00:11:39.029 --> 00:11:42.140
There are all sorts of applications for a
circuit like this.

00:11:42.140 --> 00:11:44.330
For example, a garage door opener!

00:11:44.330 --> 00:11:48.399
Push one button, the motor starts, and it
doesn’t stop until a limit switch at the

00:11:48.400 --> 00:11:51.540
end of the door’s travel opens the circuit.

00:11:51.540 --> 00:11:56.060
Of course, you’ll also want to design in
some safety interlocks, and other stuff, but hey.

00:11:56.060 --> 00:11:57.240
It would work.

00:11:57.580 --> 00:11:59.480
It might also kill someone.

00:11:59.480 --> 00:12:01.120
But it would work!

00:12:01.120 --> 00:12:03.720
So then, how does this apply to the jukebox?

00:12:03.720 --> 00:12:09.380
Well, the Wurlamatic has a microswitch that
serves as an interrupt to a latched relay.

00:12:09.380 --> 00:12:12.160
It’s the red button in our previous example.

00:12:12.160 --> 00:12:14.760
It rides along the edge of the main gear.

00:12:14.760 --> 00:12:20.140
That’s why I said there are more than seven
cams, because this is also its own kind of cam.

00:12:20.140 --> 00:12:24.920
Once the program is started, it will continue
to run on its own because a relay, specifically

00:12:24.930 --> 00:12:27.860
the Main Cam Relay, is latched in.

00:12:27.860 --> 00:12:31.060
But it’s latched through this, the transfer
switch.

00:12:31.060 --> 00:12:34.120
Now, you’ll notice that the switch doesn’t
actually get actuated...

00:12:34.120 --> 00:12:36.780
♫ abruptly slow jazzy blues kinda music ♫

00:12:40.340 --> 00:12:41.880
Ooh, twangy!

00:13:02.880 --> 00:13:06.760
Now, you’ll notice that the switch doesn’t
actually get actuated until the main cam has

00:13:06.780 --> 00:13:08.480
moved a little bit.

00:13:08.480 --> 00:13:09.480
Why is that?

00:13:09.480 --> 00:13:15.040
Well, because at first, either the Side 1
or Side 2 relay serves as the power source

00:13:15.040 --> 00:13:17.660
for the main cam relay.

00:13:17.660 --> 00:13:20.500
Electromechanics can get a little complicated.

00:13:20.500 --> 00:13:25.120
The same device can receive power from multiple
places, but so long as you sequence things

00:13:25.120 --> 00:13:27.200
correctly, you can manage it.

00:13:27.200 --> 00:13:31.520
When the carousel has reached the correct
selection, either the side one or side two

00:13:31.520 --> 00:13:33.560
relay will be activated.

00:13:33.560 --> 00:13:38.040
That starts the main cam program, just like
pushing the green button.

00:13:38.040 --> 00:13:42.860
However, the signal from the first relay will
disappear shortly after the record arm has

00:13:42.860 --> 00:13:45.140
moved from its resting position.

00:13:45.140 --> 00:13:49.670
We’ll get into the specifics of why that
happens when we get to the delightfully named

00:13:49.670 --> 00:13:52.420
Selection Accumulator.

00:13:52.420 --> 00:13:57.670
To put it more simply, a signal caused this
motor to start turning, just like the green

00:13:57.670 --> 00:13:59.610
button turned on the relay.

00:13:59.610 --> 00:14:04.050
But to keep it turning we need to generate
a new signal because we’re gonna lose the

00:14:04.050 --> 00:14:07.160
first one, just like releasing the green button.

00:14:07.160 --> 00:14:08.740
And that’s what this switch does.

00:14:08.740 --> 00:14:14.260
The transfer switch keeps the main cam relay
energized, and thus the main cam motor running,

00:14:14.260 --> 00:14:18.720
all the way through its rotation, until the
record is put back at which point it is released.

00:14:19.860 --> 00:14:20.860
But wait.

00:14:20.980 --> 00:14:22.340
That’s…

00:14:22.340 --> 00:14:23.340
a problem.

00:14:23.380 --> 00:14:27.400
Doesn’t it need to stop midway through to
actually play the record?

00:14:27.400 --> 00:14:28.860
Indeed, it does!

00:14:28.860 --> 00:14:34.060
So, there is another switch at play here,
appropriately called the Play Switch.

00:14:34.060 --> 00:14:37.153
This is actually a sort-of second red button
in this scenario,

00:14:37.153 --> 00:14:39.620
but it’s not going to totally kill the circuit.

00:14:39.620 --> 00:14:41.980
Instead, it will just sort of pause it.

00:14:41.980 --> 00:14:44.440
Ironic for a switch named Play.

00:14:44.440 --> 00:14:48.000
Whenever the transfer switch is engaged, the
main cam relay is, too.

00:14:48.010 --> 00:14:50.089
So it wants to move the mechanism.

00:14:50.089 --> 00:14:54.490
But, once the play switch is activated by
this cam, it interrupts the flow of power

00:14:54.490 --> 00:14:58.330
from the transfer switch and de-energizes
the main cam relay.

00:14:58.330 --> 00:15:01.520
This then causes the entire Wurlamatic mechanism
to stop.

00:15:01.520 --> 00:15:03.550
And now the record can play.

00:15:03.550 --> 00:15:07.450
Incidentally, this switch does double-duty
and the same switch which mutes the

00:15:07.450 --> 00:15:12.120
amplifier’s auxiliary input to give priority
to whatever record is playing.

00:15:12.120 --> 00:15:16.550
The key difference here is that the transfer
switch is still trying to sending power to

00:15:16.550 --> 00:15:21.240
the main cam relay, but it’s being interrupted
by the play switch.

00:15:21.240 --> 00:15:23.650
So what happens when the record is over?

00:15:23.650 --> 00:15:26.880
If this circuit was designed like our red
and green button thingy,

00:15:26.880 --> 00:15:29.640
well if the red button's being held in,

00:15:29.640 --> 00:15:33.480
we would need another green button to provide power and start it back up.

00:15:33.860 --> 00:15:34.820
Do we have one?

00:15:35.280 --> 00:15:36.100
Well, yes!

00:15:36.100 --> 00:15:39.100
That’s the trip switch, located right here.

00:15:39.100 --> 00:15:43.600
It’s activated by the tone arm once it’s
near to the run-out groove of the record.

00:15:43.600 --> 00:15:48.940
This then bypasses the play switch, allowing
current to go around it, and thus re-energize

00:15:48.940 --> 00:15:52.420
the Main Cam relay to restart the program.

00:15:52.420 --> 00:15:56.150
Now here’s a bit of nuance which is very neat and I want to highlight it.

00:15:56.150 --> 00:15:59.450
The trip switch works as a bypass for the
play switch, right?

00:15:59.450 --> 00:16:04.560
Which, again, the play switch stops everything
so the *record* can play.

00:16:04.560 --> 00:16:08.330
The play switch isn’t letting power through
to the main cam relay, but the trip switch

00:16:08.330 --> 00:16:10.029
provides a workaround.

00:16:10.029 --> 00:16:15.380
But that means that the programming of all
these cams needs to be done such that the

00:16:15.380 --> 00:16:20.320
play switch gets released before the tone
arm is pulled back to its resting position.

00:16:20.320 --> 00:16:25.220
Otherwise, the play switch would just cause
things to come to a halt once more as soon

00:16:25.220 --> 00:16:28.260
as the tone arm moved away from the trip switch.

00:16:28.260 --> 00:16:31.540
You can see that things were programmed just perfectly

00:16:31.540 --> 00:16:36.050
so that the play switch gets released, then the tone arm moves

00:16:36.050 --> 00:16:38.730
This is why electromechanics are so fascinating
to me.

00:16:38.730 --> 00:16:43.680
It’s a delicate ballet of logical circuit
design and physical interactions.

00:16:43.680 --> 00:16:45.779
You need to make this action to stop?

00:16:45.779 --> 00:16:48.270
Well, just make it hit a switch that kills
it.

00:16:48.270 --> 00:16:49.620
Oh, you need it to start up again?

00:16:49.620 --> 00:16:52.520
Well, just add another switch that un-does
the first one.

00:16:52.520 --> 00:16:56.220
And make sure you get the timing right or
it won’t work at all!

00:16:56.220 --> 00:17:03.060
Basically, there are a ton of if/then statements
in here, but manifested as wires and switches.

00:17:03.060 --> 00:17:06.120
It’s a form of logic, but very rudimentary.

00:17:06.120 --> 00:17:10.549
When you combine that with crazy mechanisms
like the Wurlamatic, you find yourself with

00:17:10.549 --> 00:17:15.560
a machine that can do surprisingly complex
things all through whatsists and doodads.

00:17:15.560 --> 00:17:17.880
None of that there computery business.

00:17:17.880 --> 00:17:21.720
And you'll also find some important safety interlocks,
too.

00:17:21.720 --> 00:17:26.420
For example, notice how when the record grabby
thing grabs the record from the carousel,

00:17:26.420 --> 00:17:30.990
it ends up between the two records surrounding the one it’s grabbing.

00:17:30.990 --> 00:17:35.210
Well, what if the record carousel were to
move with it in that position?

00:17:35.210 --> 00:17:38.539
A bunch of records would be broken by the
little hook.

00:17:38.539 --> 00:17:43.980
To keep that from happening, the motor which
turns the carousel is wired through this microswitch,

00:17:43.980 --> 00:17:49.029
which is only depressed when the Wurlamatic
mechanism has opened the jaw of the…

00:17:49.029 --> 00:17:50.769
right, the take out arm.

00:17:50.769 --> 00:17:52.360
That’s what it’s called.

00:17:52.360 --> 00:17:56.440
This prevents what we in the business call
"a bad day".

00:17:56.440 --> 00:18:00.230
And of course you’ll find some other switches
here that do other groovy things, like the

00:18:00.230 --> 00:18:02.609
Side 2 Release Switch.

00:18:02.609 --> 00:18:05.450
This is what actually releases the side 2
relay.

00:18:05.450 --> 00:18:10.009
There’s another one, of course, for the
side 1 relay, and these function just like

00:18:10.009 --> 00:18:12.289
the red buttons in our little demo rig.

00:18:12.289 --> 00:18:18.519
Both the side 1 and 2 relays are self-latching
to get the main cam relay, and thus the entire

00:18:18.519 --> 00:18:22.899
mechanism going, and these two switches are
responsible for releasing them.

00:18:22.899 --> 00:18:27.359
You’ll notice that it’s the same pins
which are used to turn the take-out arm that

00:18:27.360 --> 00:18:29.860
actually actuate these two switches.

00:18:29.860 --> 00:18:34.940
But of course, we haven’t answered perhaps
the most important question about this machine.

00:18:34.940 --> 00:18:37.220
What gets this all started?

00:18:37.230 --> 00:18:39.620
How does it know to start turning the carousel,

00:18:39.620 --> 00:18:43.020
and how does the carousel know what record to stop at?

00:18:43.020 --> 00:18:45.520
Or what side to play?

00:18:45.520 --> 00:18:48.320
Well, I’m gonna save that for the next video.

00:18:48.320 --> 00:18:51.620
Yeah I know, I know, I’m sorry, but this
is already, what,

00:18:51.620 --> 00:18:52.560
[NINETEEN]

00:18:52.560 --> 00:18:53.060
minutes long?

00:18:53.060 --> 00:18:54.060
Or thereabouts?

00:18:54.320 --> 00:18:57.480
But before I go, let’s look at one more
thing.

00:18:57.480 --> 00:19:01.249
I bet you didn’t think you could just remove
the record carousel, but you can.

00:19:01.249 --> 00:19:03.840
It’s actually just sitting in here.

00:19:03.840 --> 00:19:06.740
Just select a record to be played, then shut
if off.

00:19:06.740 --> 00:19:07.679
[sound of music stopping[

00:19:07.679 --> 00:19:11.330
Now, the carousel can simply be lifted up
and out.

00:19:11.330 --> 00:19:12.779
Look at what’s underneath.

00:19:12.780 --> 00:19:16.680
It’s connected to this black arm which can
be spun around.

00:19:16.680 --> 00:19:20.140
This is clearly going to some sort of mechanism
below it.

00:19:20.140 --> 00:19:25.720
That mechanism is the Read-out Arm and it,
along with the Selection Accumulator,

00:19:25.720 --> 00:19:29.340
are perhaps the most amazing parts of this entire
machine.

00:19:29.340 --> 00:19:34.120
The Selection Accumulator is what made the sound you
heard before everything got started.

00:19:34.120 --> 00:19:34.920
This one.

00:19:34.920 --> 00:19:36.780
[rapid clicking, followed by whirring]

00:19:36.780 --> 00:19:37.320
[click]

00:19:37.320 --> 00:19:39.500
[carousel spinny-buzz begins]

00:19:39.500 --> 00:19:45.040
Notice when I select a record that the buttons
stay depressed until that sound stops.

00:19:45.040 --> 00:19:46.940
Then they pop back out.

00:19:46.940 --> 00:19:49.480
That's actually the reason there's a reset button in the middle,

00:19:49.480 --> 00:19:52.520
so that way if you press the wrong button you can pop it out.

00:19:52.520 --> 00:19:56.880
Now, listen closely as I select a series
of records.

00:19:56.880 --> 00:19:58.120
A1

00:19:58.120 --> 00:20:00.560
[whirring]

00:20:00.560 --> 00:20:01.060
[clunk as it stops]

00:20:01.180 --> 00:20:01.920
C1

00:20:02.920 --> 00:20:03.440
[whirring]

00:20:03.440 --> 00:20:03.940
[click]

00:20:03.940 --> 00:20:05.300
[whirring]

00:20:05.300 --> 00:20:06.000
[clunk as it stops]

00:20:06.060 --> 00:20:07.100
E1

00:20:07.740 --> 00:20:08.640
[whirring]

00:20:08.640 --> 00:20:09.140
[click]

00:20:09.140 --> 00:20:10.120
[whirring]

00:20:10.120 --> 00:20:11.120
[clunk as it stops]

00:20:11.120 --> 00:20:12.500
G1

00:20:12.500 --> 00:20:14.040
[whirring]

00:20:14.040 --> 00:20:14.540
[click]

00:20:14.540 --> 00:20:15.040
[whirring]

00:20:15.040 --> 00:20:16.120
[clunk as it stops]

00:20:16.120 --> 00:20:17.040
and J1.

00:20:17.900 --> 00:20:19.800
[whirring]

00:20:19.800 --> 00:20:20.300
[click]

00:20:20.300 --> 00:20:21.360
[clunk as it stops]

00:20:21.640 --> 00:20:24.680
Did you notice something changing with each selection?

00:20:24.680 --> 00:20:27.080
[whirr...

00:20:27.320 --> 00:20:27.980
[whirr...

00:20:27.980 --> 00:20:28.480
click]

00:20:30.080 --> 00:20:31.120
[whirr...

00:20:31.120 --> 00:20:31.620
click]

00:20:32.860 --> 00:20:34.300
[whirr...

00:20:34.300 --> 00:20:35.000
click]

00:20:35.680 --> 00:20:37.620
[whirr...

00:20:37.620 --> 00:20:38.180
click]

00:20:39.140 --> 00:20:40.360
What's going on?

00:20:40.420 --> 00:20:44.800
Well, stay tuned because in the next video
we’ll find out.

00:20:44.800 --> 00:20:45.660
Thanks for watching.

00:20:45.660 --> 00:20:50.420
I really hope you enjoyed this video and that
my explanations were easy enough to follow.

00:20:50.420 --> 00:20:55.320
Electromechanics are really quite simple,
but they can be a little confusing.

00:20:55.320 --> 00:20:59.080
When you use switches and relays to make sequences
and interlocks,

00:20:59.080 --> 00:21:01.080
it can seem to get out of hand.

00:21:01.080 --> 00:21:04.639
In fact, these here are the schematics for
this machine.

00:21:04.639 --> 00:21:07.229
They’re super easy to read!

00:21:07.229 --> 00:21:11.320
You might have thought this was a pretty simple
device with what you’ve seen up ‘till now,

00:21:11.320 --> 00:21:12.230
but trust me.

00:21:12.230 --> 00:21:17.400
When we explain where these buttons go, it’s
gonna get a lot more complicated.

00:21:18.240 --> 00:21:20.440
I think I’ll play some music now.

00:21:20.440 --> 00:21:21.620
How about…

00:21:21.620 --> 00:21:22.620
T1?

00:21:22.620 --> 00:21:23.980
[ buttons being pressed ]

00:21:23.980 --> 00:21:25.720
[ selection accumulator whirring ]

00:21:25.720 --> 00:21:29.000
[ buzzing as carousel moves ]

00:21:30.160 --> 00:21:32.080
this is gonna take a while...

00:21:33.420 --> 00:21:36.220
shoulda picked something in the C's or D's...

00:21:38.740 --> 00:21:43.400
[ clunk, followed by various mechanical sounds ]

00:21:43.400 --> 00:21:44.580
[a low hum]

00:21:44.580 --> 00:21:48.320
♫ scratchy low-fidelity smooth jazz ♫

00:21:58.200 --> 00:22:00.680
♫ audibly improved smooth jazz ♫

00:22:02.260 --> 00:22:05.220
I liked that delivery so much and then it
fell apart!

00:22:05.220 --> 00:22:08.660
And a staggering number of switches, rel … ooh.

00:22:08.660 --> 00:22:10.780
Ha, that’s the, that’s the end of the
sentence!

00:22:10.780 --> 00:22:11.280
[laughs]

00:22:11.280 --> 00:22:11.780
oops.

00:22:11.780 --> 00:22:13.100
Did I say “of course” weirdly?

00:22:13.100 --> 00:22:16.710
It’s a little late now, ‘cause I’m already
moving it back, but I think I did.

00:22:16.710 --> 00:22:21.600
However, this clever mechanical program wouldn’t
make for a useful jukebox…

00:22:23.180 --> 00:22:26.120
it’s later than you think it is, I’m kinda tired.

00:22:26.129 --> 00:22:28.160
When I press it, it morment...

00:22:28.160 --> 00:22:29.560
[weird stress
sounds]

00:22:30.440 --> 00:22:31.960
Those are fun words!

00:22:31.960 --> 00:22:33.880
They aren’t words, they’re just sounds

00:22:33.880 --> 00:22:35.879
So what happens when the record is over?

00:22:36.380 --> 00:22:36.879
Oh.

00:22:37.680 --> 00:22:40.279
It’s not phrased as a question that I know
the answer to.

00:22:40.279 --> 00:22:42.029
I should have added a paragraph here.

00:22:42.029 --> 00:22:42.820
I need to…

00:22:42.820 --> 00:22:45.040
I need to say something that’s not in the
script.

00:22:45.040 --> 00:22:46.320
That’ll go well.

00:22:49.280 --> 00:22:53.560
Stay tuned for next time when we 
ACCUMULATE SOME SELECTIONS

00:22:54.420 --> 00:22:57.520
I'm very excited for the next video.

00:22:57.520 --> 00:23:00.040
I think you're gonna like it.

00:23:02.000 --> 00:23:02.960
doo doo doo doo