How a quartz watch works - its heart beats 32,768 times a second

this video is sponsored by Nord VPN in the world of

watch

enthusiasts there can be a bit of snobbery that says that mechanical

watch

es are far superior to battery operated watches and I can understand why you have these objects that are really intricate and really precise. really small and yet completely mechanical, that's surprising, it's a really desirable object, but when you discover how the mechanism

works

inside a battery-operated

quartz

watch, it becomes equally desirable, at least it was for me and It's probably the next watch I'll buy. I understand once my pebble dies, but anyway, this video is about the amazing mechanism that powers a

quartz

watch.

If you want to create any type of timing device, the first thing you need is some type of thing that oscillates and you know how long each one lasts. oscillation takes a good example is a grandfather clock, then you have a pendulum where it is known that a single swing of the pendulum takes one

second

, you know the period of oscillation and you can use it to drive the clock mechanism, but if you try to wear a clock Pendulum on the wrist would not work because the movement of the hand would make the pendulum swing all over the place.

You have the same problem if you put a grandfather clock on a grandfather clock. It was actually the need to be able to tell the time in C which prompted the development of pendulumless clocks which eventually led to mechanical wristwatches in a conical clock, the pendulum is replaced with an oscillating mass on a spring a bit like this, except this arrangement is not much better than the pendulum, it still depends of gravity and it is going to oscillate in a boat, so a coil spring and a rotating mass are used instead, the rotating mass repeatedly winds and unwinds the spiral spring in this way, the flywheel mechanism is the basis of most mechanical watches. and could be incredibly accurate, a high-end mechanical movement could only lose up to five

second

s a day and yet a battery-powered watch can easily be much more accurate than that and they can achieve that feat with a small tuning fork, for example. what the grandfather clock uses a pendulum with a known period of oscillation and mechanical what uses a mass on a spring with a known period of oscillation and a battery-powered clock uses a tuning fork with a known period of oscillation this particular tuning fork oscillates 440

times

per second which is an audible frequency also known as above-middle C.

You may have already spotted a problem with using a tuning fork to keep time, which goes like this: you hit it to make it vibrate, but then the vibration slowly decreases until it no longer vibrates, so how do you keep it vibrating and Also how do you convert that vibration into the ticking of a clock? Actually, both problems can be solved with an electromagnet. Consider this simplified tuning fork. I don't know if you can call him. Tuning it, I mean, it's a metal ruler and a vise, but anyway, like a tuning fork, if you hit it, it will vibrate at its natural resonant frequency.

Unlike a tuning foot, you can't hear it because the frequencies are too low, but it's like a tuning fork. if you leave it on long enough the vibrations will eventually reduce to nothing eventually damn Isabella but now look at this setup I have an electromagnet here these are the wires that go to the electromagnet this one is connected to a nine power supply volts, but this one just isn't connected to anything, so the circuits are broken, the electromagnet has no power, but the other end of the power supply goes to the ruler, so if you touched this wire against the ruler , the circuit would be complete and the electromagnet would turn on.

I have also connected a permanent magnet to the ruler which is repelled by the electromagnet when it is on, so what you can do is place the wire right next to the ruler so that when the ruler gets too close to the electromagnet it completes the circuit and is repelled by the electromagnet is a bit like pushing someone on a swing every time they get too close to you you push them away you are not changing the resonant frequency of the person on the swing you just keep them failing You might as well do it here, as a benefit Additionally, the current in this circuit that turns on and off at regular intervals can also be used to regulate the ticking of the clock.

A more sophisticated and miniaturized version of this configuration can be found in watches manufactured between around 1940 and 1960, the Accutron had a tuning fork inside that vibrated 360

times

per second, so if you placed the watch against your ear you would hear this sound. , which is nice, the real revolution came with the discovery of piezoelectric electricity. I explained the piezoelectric effect. in my last video and wider magnifications on certain crystals, the quick summary here, if you take a quartz crystal and you cut it the right way and then deform the crystal, like if you hit it for example, then your voltage measurement a through the glass and conversely, if you apply a voltage across the glass, the glass will warp, so if you look inside a digital or analogue watch, which is battery operated or the back of a war watch which is powered with batteries, you will find this component and if you remove it the protective outer case is a quartz crystal, of course, in the shape of a tuning fork.

If I move this crystal, it will sound like a tuning fork, except you won't be able to hear it because the frequency is too high for our ears, but because it's piezoelectric, it not only produces this inaudible sound, but it also produces a detectable oscillating voltage. This is a USB oscilloscope, so what you are seeing here is the voltage detected across the probes and I have connected the quartz tuning fork. to the probes, so at the moment nothing happens, but look, if I move it, I see that wavy pencil, so the voltage across the probes goes up and down because the piezoelectric crystal flexes back and forth, so the voltage it produces goes up and down. down we could take a screenshot and then try to determine what the frequency is or we can switch to the frequency view where the oscilloscope will actually show us the frequencies so now if I move it around I see that peak that appears just put a small script. line at 32.7 kilohertz and look when I move it, that's exactly where the peak appears, like a tuning fork, the vibration is short lived and you need to find a way to maintain it like we did with the electromagnet but with a piezoelectric tuning fork.

You can do something really clever: you take the voltage coming out of the tuning fork, that oscillating voltage, you put it through an amplifier and then you feed it back into the tuning fork and that's how you keep the tuning fork vibrating at its own natural resonant frequency. I bring the quartz crystal back and feel it in that feedback amplification circuit and look, here's that permanent spike now at 32.7 kilohertz. That 32.7 kilohertz measurement is only accurate to one decimal place, and I happen to know that the actual true value is 32 point seven six eight. kilohertz or in other words 32.768 hertz, quartz crystals are calibrated at the factory to have that exact frequency, so they add gold to the tips of the tuning fork and then slowly chip off little bits until the frequency is exactly right, if you know its powers of two, so you may have noticed that it is 2 to the power of 15, but why is that number exact?

There's actually a smart reason for it, but it's two really smart reasons. The first is that it must be above 20,000 Hertz because that is the limit. than people can hear and you don't want your watch to make an audible whine, so let's do it above 20,000 Hertz and two to the 15th power is the first power of two that is above 20,000, but why it has to be a power of two, this is where it gets really clever because you can take an oscillating signal like that and you can pass it through a chain of flip-flops and it will convert that 32.768 damage signal into a 1 Hertz signal a beep per second and you can use that one beep per second to mark the second hand of your watch and when I say chain of flip-flops, what I mean is that a flip-flop is just a small logic circuit.

I'm not going to go into how a flip-flop

works

. It can be built from gates and/or gates and things like that, but you should know that a flip-flop can maintain a state, so you give it a signal and it turns on and it will stay on until you send it another signal and then it will turn off. and it will stay off until you send it another signal, so let's see what happens when we chain fifteen of these flip-flops together, to start, let's look at the first flip-flop in a chain, so remember that you have this signal coming from the quartz tuning fork and it's a mapping wave, but this is a digital device, it's a smart flip-flop, if you will, so it's expected to turn on and off, there's going to be some processing that takes that sine wave. of the quartz crystal and turns it into a square wave like that, so you can go in or out of this flip-flop and the logic inside the flip-flop is arranged so that any signal that comes in the on position The flip -flop will flip as soon as the power signal goes off so it's on the fall of the power signal so here's the incoming signal and as it falls that's when it flips like this okay and then comes the next signal. comes in and just as that signal cuts off, it flips to the right again and then the third signal comes in and flips, the fourth signal comes in and flips to the right, so that's the off position, that's the on position of the flip -flop and you will see that the flip-flop is flipped to the on position every second signal that comes in, so all odd signals are flipped to the on position, so if you look at the frequency at which it is turned on This flip-flop is half the frequency of the incoming one. signal and here is the covering bit, you take the signal from this flip-flop and pass it to the next flip-flop in the chain so that this flip-flop turns on and remember that we have organized the logic inside this flip-flop to which will flip or fail when the signal coming in is turned off at the time it is turned off, then the moment this turns off, this turns on like this, then this turns on again and then the moment this turns off one goes out on the right and considering these two on their own, you'll notice that this one spins half as often as this one and this one goes off half as often as the signal coming in on the right and then you chain this one with this one. so you have on/off on/off and but then this turns on when this turns off correctly and everything happens again on off on oh and then this turns off at the same time with the off signal of In this case, the important thing is that the frequency of the flip-flops decreases by half each time you advance to the next flip-flop, so think that you have an incoming signal that is 32,768 Hertz, this is on and half of that is 16,000 386 that 84, so there's no reason for you to look there, by the way, this one is half the frequency again, which is 8192 firings per second, if you like, this is half of what 4096 is and so on down the chain, these are powers of two, so you have an incoming signal with a frequency of 2 to the power of 15, then this has a frequency of 2 to the power of 14, this has a frequency of 2 to the power of 13 to the power of 12 2 to the power of 11 10 9 8 7 6 5 4 3 2 1 this is 2 to the power of 1 that is the frequency of that guy has 1 is 2 like a frequency of two flip-flops per second so this is 2 to the power of 0 or 1, so this changes every second.

I actually have a redundant flip-flop here, you don't need 15, you need 14, that was my mistake, it's called error shutdown and it happens frequently. In programming, you then use the signal from this flip-flop to power what is called a stepper motor, which is a motor that can rotate by an exact amount each time it receives a voltage, so you can use it with a series of gears to move the second. hand on your watch and then some other gears to move the minute hand and the hour hand as well and of course because this is an electronic signal to begin with, you can avoid the mechanical world entirely and Simply use that signal to drive an LCD display and that's how a quartz watch works.

Any half-decent quartz watch will only lose about a second a day at most, which is much more accurate than even a high-end mechanical watch, but of course a quartz watch is not. The most accurate way to keep time The most accurate way we have now is with an atomic clock, but did you know that an atomic clock still uses the vibration of a quartz crystal to keep time, it just also uses cesium atoms to keep time. adjust the time? vibrations of the quartz crystal if it seems to be drifting, so yes, even an atomic clock uses a quartz crystal.

I'm not going to explain how an atomic clock works now because there are many videos explaining the best video explanation I've found is on the everything channel so I recommend you jump on there and watch. I'll put a link on screen N and in the description, but I also recommend that you subscribe to that channelbecause lately he's been making these epic cinematic videos where you also learn about really amazing science, so go there what's the video about atomic clocks, but also subscribe. This entire video came about because I was looking at how computers know what time it is and how they sync around the world using the network time protocol because I was doing a security audit and it turns out that having an exact time of what your devices are is important. for security.

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