Hi. Check this out! I'm very excited about this. This is a Belovo Accutron Space View watch. Space Age technology right out of the 1960s.

Isn't it just gorgeous? This particular model is actually almost, uh, 50 years old. It's a 1968 model or what's called the M8 Uh model. Accutron Space View. Now, Acuratron are an American watch manufacturer.

a very old one and they make lot. They still make these Acutron Uh watches and they come in many, many different flavors, but this one is my absolute favorite. It's called the Space View because you can see the mechanism down inside. And yes, it does look unlike any watch you've ever seen.

This is actually the world's first transistorized watch, and the original model came out in 1960. The original Accutron Model 1960, and it uses a tuning fork mechanism. It it's not a quartz crystal watch, it uses a tuning fork that actually, uh, resonates at 360 Hertz and you can see two coils in there, which actually, uh, keep that tuning fork oscillating. And there's a single transistor oscillator in there.

and you might be able to actually see the Um components down in there. They're just individually soldered to like little tags. and there's actually a single transistor in there. The first model in 1960, actually.

Oh, for the first five years, up until about 1965, used a Germanium transistor, and then they switched over to an Npn transistor inside this thing. But it's the remarkable tuning fork. You can see the tuning fork in there like that. You can see the two arms of the tuning fork here.

one there and one there and you can see how they're actually welded onto the Uh metal that goes over the coil there. so the entire metal part there is free to move back and forth across the coil on either side, and there's a gap down in the middle there. And the most remarkable thing about this tuning fork mechanism is that it was, uh, super duper accurate. At the time, it was the world's most accurate watch, down to about like a couple of seconds per day.

And that was that. Beat the pants off any mechanical watch at the time. basically until Quartz crystal Oscillator Uh watches came along. So these were heavily used in by Uh.

Nasa for the space program and Accutron Uh. tuning fork is on an instrument um, that was left on the moon by Apollo 11, for example, and dozens and dozens of other space missions during the 1960s relied on and a tuning for an accutron tuning fork mechanism. Uh, as for their timekeeping source, it was basically the most accurate clock oscillator available. Now you can see this is actually the M8 model stainless steel backing.

It's 18 carat gold plated this one. It is waterproof. Um, but yeah, after 50 years, unless you've had it properly serviced and everything else, yeah, you shouldn't actually be using it in there. We've got the battery and one of the most interesting aspects of it is actually you might notice that there's no crown on the outside of this.

How do you set it? Well, You actually flip up that little lever like that and bingo, You can turn the hands like that. Beautiful. Now, none of these are Belovo watches. Actually, the accutrons contained a calendar in them.

The mechanism uh, would that would have been too complex for the mechanism inside this to handle a calendar function, but they were super duper accurate. The world's most accurate timepiece basically um, in the 60s and the tuning fork mechanism was immune to uh, shock and vibration and things like that. If you really shocked it hard enough, it might upset it for a second, but basically it would just keep going. But there are two remarkable things about this tuning fork that I think make this watch pretty unique.

And the first one is the second hand look. It just continually sweeps like that. It is absolutely gorgeous. It does not go tick tock tick tock.

It does not tick in second intervals. It is a continuous sweep movement. It is absolutely gorgeous. and it gets that by way of the tuning fork.

Uh, mechanism itself is then a direct um, drive through those uh, cogs there that actually drive the sweep second hand, and then the minutes and then the hours hand. So that's how it's able to get that gorgeous sweep on it. Oh, fabulous. And the second remarkable thing about the accutron mechanism is that it doesn't tick.

it hums and you put it up to your ear. Oh, that's beautiful, Really. So these acciotron watches were the world's best timepiece in the 60s. Uh, it used to be the official watch given to you know, foreign dignitaries by the Us government.

As you know, a show of our remarkable technology, I guess. But yeah, the world's most accurate watch, Of course, completely supplanted by, um, cheap ass two dollar quartz crystal uh watches which came out after that. But up until that time. Wow.

these were the ducks guts. and you'll notice that my one is actually in remarkable condition. And you know all of the silk screening on the front glass is all still there. and the original hands with the luminescent uh dials on them are still there.

And yeah, it's just a very first class condition for a, uh, basically, what is a 50 year old watch? Now, this is not the original band on it. this is a Spiegel. uh, third-party band. A Pretty, you know, a reminiscent of the era though.

So this isn't the original one. but it does complement it very well. And the accutron mechanism is, uh, known as the two one four mechanism and as I said, came in many different types. Uh, mostly they were not the see-through one.

Like this space view. There's many different versions, there's many different fake ones out there by the way, with fake hands and fake glass and all sorts of things. you've got to be, um, quite careful if you're a a collector of these things and uh, you know, trying to if you bought one that's uh, you know, been refurbished or something like that. It may not have all the genuine parts, but I'm led to believe that my one is still all the genuine business.

And for those watch aficionados wondering how big this is, it is actually a very small face. It's about 34 millimeters across and I've got a really small wrist. And yeah, it still looks fairly small on my wrist, but isn't that gorgeous now. It runs on a modern Dart 387 type battery, but it's got a plastic ring in there to do that.

and uh, modern batteries are one point the silver oxide ones. The 1.5 volt ones can actually, uh, cause an issue with the coil wasn't around and designed for that higher voltage. It was designed for one point older 1.35 volt battery. so that can be an issue if you're trying to replace these so you can actually get these watches, uh, modified with a diode in series with the coil to actually, uh, drop that voltage.

So I'm not actually sure if this one has the diode modification or not though Now, unfortunately, I don't have the uh correct tool to open this. I could make one on jury rig one, but I've heard that if you don't know how to take these apart properly, you can actually damage them. Not Not just the back of course, but the internals. So yeah, I'm not going to do that yet.

I haven't done the research required to do that properly yet, but thankfully we don't have to because there's an awesome web page which I'll link down below which has not only all the internal uh, high-res photos, but it also has the circuit diagram as well and the E3 a cool 3d diagram of the mechanism and why it's so different. Let's take a look now. Absolutely full credit to the author of these uh through awesome 3d models are Burka visas. It's quite an old website, but I'll link it in down below.

It has a ton of information. Everything you could possibly want to know about the Belovo accutrons, the mechanisms, the calibration, the rephasing of the coils and the batteries, and the how are all the mechanisms work and servicing and everything. It's absolutely fantastic. Anyway, on the left hand side here you can see a typical Uh mechanical watch of the 1960's era.

I'm not sure if they're simpler these days, probably not by a huge amount and they're quite complex. They use your traditional balance wheel and the hairspring and all sorts of stuff. and but compare that to the right of the accutron far simpler with its uh tuning fork there which then has got some reduction, uh, gears and everything else. and I won't ex pretend to know about all the mechanical details of all that sort of stuff.

and it, uh, vibrates by a way of the coils in there. That and the transistor oscillator that keeps it going at the mechanical resonant frequency of 360 hertz of the tuning fork and it was far simpler. And that's also how you get the gorgeous sweep hand that we saw before as well. So ah, it's just beautiful design.

I love it. And the other remarkable thing about the accutron mechanism is that it wasn't really affected by the accuracy of it, wasn't affected by uh, the friction of the wheels and the lubrication and the servicing and all that sort of stuff. as uh, mechanical watches are much more susceptible to that in terms of accuracy. So the accutron was much more reliable mechanism, and the actual tuning fork metal itself was made out of what's called knife span C, which has a very low temperature coefficient of expansion.

So yeah, basically temperature had almost no effect on the accuracy of the acutron. And if we have a look at the schematic here, once again, this wasn't done by me. This is done by the guy on the website here and you can see on the left hand side was the original circuit from 1960 to about 1965 I believe, which used a a Germanium Pnp transistor. Ay triple One seven for those playing along at home.

Um, and you can see on the right hand side which is what's inside my one, the M8 and from about 1965 onwards they switched over to an Npn Silicon type transistor and you'll notice that the batteries um, they've got those uh, back to front there and you can see that there's basically uh, two coils, two drive coils d1 and D2 and you saw those uh inside the mechanism uh, itself. They're inside the little uh cups which go which attach to the tuning fork and there's a feedback coil in there as well. I'm not sure where the feedback coil is in the whole scheme of things, but it basically is a resonant, uh, single transistor, resonant oscillator circuit. The resonant frequency is not dependent upon the R and C values in there, the component values is dependent upon the actual Uh physical resonant frequency of the tuning fork itself.

All right, let's see if we can pick up the beautiful humming sound from this. I'm not sure if we will, but we'll give it a try. I've got my wireless mic strapped to it uh, inside my uh flight case that I have for my cameras for site filming and stuff like that. I'll close it up and it should be fairly silent.

Let's give it a bill. Now, if we actually feed the output into a scope, we can take a look at the spectrum here and see what we get. It is quite a noisy waveform, so you do have to like clean it up even in that acoustic little or my pathetic attempt at an acoustic chamber there. And um, the dominant uh frequency here is a hundred hertz.

So um, I that might be coming from the 50 Hertz pickup. I don't know what's like double. I don't know what's going on there anyway. Um, that dominates.

But if we slide this along 360 Hertz center frequency, we've got a peak there. and that's spot on to our tuning fork frequency that we, uh, expect from this thing. It works. at 360 hertz, it's a physical property of the tuning fork there.

And yep, you guessed it, it's bang on. They don't call it an accutron. for nothing, you can see a waveform there. It's pretty crusty.

Even if I don't talk, it's yeah. If I give it a bang bang, there we go. I tap on the case. Um, it it.

You know it's still crusty. But hey, our Fft bought that out and we can actually go in there and we can clean this up as well so we can go into the acquire and then we can go into here and we can set well. that's that's normal refresh mode. And then we can actually go in here and actually set a filter frequency.

You'll see that it'll get cleaner and cleaner. This is applying a digital filter and there we go. 900 Hertz Starting to get pretty clean now, but even with a Hertz filter on there, you can actually see that the 100 Hertz is going to dominate. Let me freeze that and you can see that the dominant frequency is around about 100 hertz there.

So yeah, but trust me, there is. Well, trust the Fft. There is a 300 Hertz Uh Frequency, which is the tuning fork tucked away in there somewhere. And just for kicks, I thought I'd film this at a thousand frames per second with my Sony Rx100 and you can actually see here it is a thousand frames per second.

You see the sweep hand slowly moving like that and you can see the two Uh cups on the end of the tuning fork there just vibrating in or out. It's brilliant and you can probably do the math on that if you know that this is shot at a thousand frames per second into a 50 frames per second video. Hmm. go for it.

Actually looking at this high speed footage, I'm not convinced that that's entirely smooth. Is my are my coils not phased correctly for the battery or whatever? Hmm. I'm not sure I have to get back to you on that, so I hope you enjoyed that. Look at this Belovo Acutron Space View 214 A classic watch from the 1960s.

Not only just a classic, but a complete paradigm change in the technology used for uh, you know, timepiece. Uh, timekeeping Watch Timekeeping like this. and it was used on many Nasa space missions and various things because it was the most accurate thing that they had available at the time. But yeah, yeah, it's like not much these days.

but you can still marvel at the the engineering that went into this and actually simplifying, uh, the mechanical watch mechanism and just getting it more compact and simpler and immune to vibration and temperature and all. and lubrication and maintenance and all sorts of stuff, it absolutely stunning. Hope you enjoyed it. Catch you next time! Hi! Welcome to Tear down Tuesday! We've seen this one before.

This was sent into the mailbag segment uh, recently by Chris Boden from the Geek Group. So I'll link in the Geek Group down below. Thank you very much Chris! He went to a lot of expense and effort to uh, send this to us and what it is is it's an analog computer for an inertial navigation system, an Astro compass uh system used on the B-52 bomber. So let's check it out.

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