- This is a "perpetual motion" device. That's the first time I've
ever used a green screen in one of my videos. But it's important to put perpetual motion in inverted commas because
perpetual motion doesn't exist. Actually, the designer of this device calls it a perpetual motion simulator. I quite like that. Actually, I quite like perpetual motion simulators in general because we know that perpetual
motion isn't possible, so it's fun to try and figure
out like where's the trick? And in this particular case, the trick is some really
lovely engineering. To be clear, I don't like
perpetual motion simulators that are designed to scam people. The list of those is endless, but the creator of this device is very clear that it needs batteries. In fact, I did some bookkeeping after buying all the stuff for this video, and I chuckled at these two entries, perpetual motion machine
followed immediately by batteries for perpetual motion machine. To figure out how this works,
we really need to look inside, and thankfully through the
magic of buying two of them, I already have a taken
apart one right here. And that's the second time
I've ever used green screen in one of my videos. The idea was to remove the wooden base and replace it with a transparent
one, because, you know, I like to make transparent
versions of things. The problem was when we put
all the gubbins back in, we couldn't get it working again. So while this is good for
showing you what's going on, it's a bit unsatisfying because
it doesn't actually work. And then I thought, "Wait a second, why don't I try and contact the
person who made this thing?" William Le was very helpful giving advice on how to get this thing
working, but we never could. So eventually I asked if
he would make one for me. And so here is my third
perpetual motion simulator. Isn't it beautiful? I'm hugely grateful to William
for making this for me. He took the time to figure out how to work with unfamiliar materials, and the result is fantastic. By the way, William is the
creator of this design. There've been hundreds of knockoffs since, but if you're planning
to get one of these, I really hope that you'll
go to the original creator. The link to William's Etsy
page is in the description. So let's figure out how this thing works. Well, even without looking inside, we can make some educated guesses. Without the device turned on, you can see the losses due to friction. Gravitational potential energy
is turned into kinetic energy and that kinetic energy is turned back into
gravitational potential energy. But look how much less
gravitational potential energy there is after that process. So when the device is turned on, the ball must be given some
additional kinetic energy at some point. And the only thing I can
think of is electromagnets. And in this transparent version,
that's what you see here. But that's not enough on its own. If you simply turn on the electromagnet, well, the steel ball will
accelerate towards it, but once it reaches the electromagnet, it'll be harder to leave. This is what happens when
I put a permanent magnet in place of the electromagnet. So the electromagnet needs
to be on during the approach, and then off once the
ball reaches the magnet. That's where this component comes in. This is an inductive proximity sensor. Actually, no. This is an
inductive proximity sensor. This is one of these that's
been deconstructed by William so that it'll fit inside
his sneaky device. The way it works is when you
supply power on these two wires an oscillating current passes
through the coil inside which induces an
oscillating magnetic field. You might know that a
changing magnetic field induces a current in nearby metals. Well, an oscillating magnetic field is changing all the time. So when the steel ball approaches, an oscillating current
is induced inside it. Now that oscillating electric
current inside the ball has an oscillating
magnetic field of its own. And the way the physics works out, that induced magnetic field actually opposes the
magnetic field of the coil. So as the ball approaches, the total magnetic field goes down. That's detected by the sensor
and this little LED light up. But for the purposes of this circuit, it also sends a signal
voltage down this third wire. So now we can have the
electromagnet turn on when the ball gets to a certain position. We can then decide like how long do we want the
magnet to be turned on for? I've attached a voltmeter
across the electromagnet so you can see a voltage is supplied to the electromagnet for
about 10 milliseconds. Final couple of things I wanna look at. What are these things?
Well, these are capacitors. You really need to give that
electromagnet some juice. So instead of powering it
directly from the battery, you charge up these capacitors
and then power it from them. I'm not sure how long it takes to charge up these capacitors, but if you send two balls
down at the same time, the second ball doesn't make it. But if you leave a little
gap between the two, then they both come back to the top. And actually looking at the
voltage graph from earlier, the capacitors don't
discharge very much at all. So you can imagine it
wouldn't take much time to get them back where you want them before the next ball arrives. These two blue components are important. They allow you to adjust a couple of the parameters of the device. You tweak the top one if you want to adjust the
strength of the electromagnet, and you tweak the bottom one if you want to adjust how long
the electromagnet is on for. And these are important because each one of these
devices is handmade. There's gonna be a slight variation in the distance between
the rails and the sensor, the length of the track and so on. So you need to be able
to fine tune these things after it's all put together. I mean, you don't have to. William does it before he sends it. The final thing is the power button. You know, you really don't want your perpetual motion machine
to have a power button. It kind of spoils the
illusion a little bit. So here under the acrylic, you
can see a capacitive sensor. When you touch it, you're adding the capacitance of your body to that little bit of acrylic there. That sensor can detect
the change in capacitance, and the circuitry interprets
that as a button press. And so in the wooden version, it's as if there is no power button. On the subject of
perpetual motion, actually, occasionally I'll make a
video that demonstrates some physical principle
typically involving magnets, and there'll be a discussion
in the comments of like, "Would it be possible to
slightly adjust the setup so that the thing keeps spinning forever or the thing keeps bouncing
up and down forever?" Things like that. A good example is my video about
the spinning ballerina toy. What if you had two magnets
or a ring of magnets so that the ballerina just
constantly moved round in a circle? But actually you'll notice in that video, I'm always moving my hand. The magnet is always
getting closer and closer to the ballerina, and the ballerina is getting
further and further away. And of course, the ballerina is pushing back against my
hand, so I'm doing work. My hand is moving some distance in the direction of an applied force, so there's no free energy to be had here. And of course, there's no
free energy here either, unless you don't pay for your electricity. ♫ perpetually smooth jazz ♫ And thankfully through the
magic of buying two of them... And thankfully through the
magic of buying two of them, I already have a taken
apart one right here. I picked up the wrong one. I used to get these phone
calls where they'd be like, "Hello, am I speaking to Steven Mould of such and such address?" "Yes, that's me, that's my address." And they say, "I'm calling
from insurance department." Okay, they know my details. They must be calling from
the insurance department of my insurers. But then you carry on the conversation, it turns out they're just trying
to sell you life insurance or something like that. It's really interesting to know how these annoying
practices came about. It's also interesting to know how you can stop this kind of phone call and other intrusions into your life thanks to the sponsor
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