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Project Logs / Re: Diy optical pickup for guitar -- is it possible?
« Last post by BillTodd on Today at 04:22:16 AM »
For analogue audio work a 20MHz bandwidth 'scope is plenty. You don't need serial format converters or logic analysis functions.

If you are going to blow serious money on a new one, then buy the best most highly featured one you can afford.

If you just want something to debug your pickup then buy something cheap and cheerful , it will always be useful even if you buy something better.

Beware of the youtube reviews, They don't spend their own money and, like Dave's review yesterday, will compare a 70 currency unit ($) device with one costing 12000.

Seek out other purchasers/users of the device on forums and ask their opinions.  BTW that little scope wasn't too bad, but I felt it was still too expensive , at 40 cu it would have been a good buy .(you have to be cautious about the results of any instruments when working near their limits)

If you don't already have one, get yourself a copy of 'the art of electronics' by Horowitz and Hill .  I think it will fill a few gaps in your knowledge.and is always useful as a reference.













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How do I?? / Re: OLD LATHE
« Last post by Pete. on November 11, 2019, 08:47:32 PM »
Another thing to watch out for is that some of the gear ratios in the table might not physically fit. You can only find this out by trying. You can swap the drivers and the driven gears around though. The stud gear and the B gear are drivers. The A gear and the Screw gear are driven.

So if you look at 2.75mm it looks like the 80 tooth B gear won't reach the 32 screw gear because the 127 A gear is too big. You can swap the 32 and 127 around and the ratio won't change. Also you can swap the stud gear with a B gear if you want so the 44 and 80 could change places.

It's just a matter of seeing what will fit before you go and have a proper chart engraved. If you just can't make a combination work then get the program in the link above, load your gear set into it and use it to generate a list of optional gear trains. Sometimes there are dozens of options.
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How do I?? / Re: OLD LATHE
« Last post by Pete. on November 11, 2019, 08:33:04 PM »
Okay, using the program nthreadp from here it looks like you can get most of the common imperial and metric threads with the gears you have got. The only really common one you can't get is 1.75mm pitch (which is the pitch for M12 coarse).

The threads you can't get are in red. I haven't been through and double-checked these so there may be errors, but I think they are pretty good.

Where it says I you can put any gear that will fit, as it just need an idler to fill the gap. For this you have to swap the spacer on the screw gear to the front. so it's a simple gear train not compounded.
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How do I?? / Re: OLD LATHE
« Last post by celsoari on November 11, 2019, 06:50:09 PM »
I suspect this lathe is a Portass. There are some similarities. The cover of the reduction train gears are identical. The support of flat pulleys is also identical.
however the bed and feet are quite different.
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Project Logs / Re: Diy optical pickup for guitar -- is it possible?
« Last post by sorveltaja on November 11, 2019, 06:29:27 PM »
This post is an off-topic, but sort of related, because it considers the recommended kind of measuring device, oscilloscope.

After pondering, and watching countless amount of Youtube review videos about oscilloscopes(mostly EEVblog's, and also reading his forum),
I came to the conclusion, that the desktop one could offer a lot more functions and options, than I could ever need or fully understand.

One thing, that I must say: This kind of project (optical pickup for the guitar) definitely does not require a fancy 'full-featured' desktop oscilloscope, for the experimenter to observe signals.

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Totally off-topic:

When I'm talking about having a desktop oscilloscope, it's more like a part of my own journey, as I have wanted to have one for years now.

Then came the question: which brands are available in finnish stores? Owon's cheapest model(SDS1022) has nice, big 7 inch screen in it, but for some reason, there isn't too many reviews to be found of that online, so the reputation isn't confirmed in any way.

After all, Rigol is the one, that I ordered. As Pekka said "..but that is learning curve". Probably a steep one, that holds true for me, when I get that device in my clumsy paws.
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Back to the original subject. As Russ mentioned, 'Turning a sine wave to square is easy. Just apply massive gain'. But how much gain can one apply to a single op-amp, without making it self-oscillating? Or is it something, that requires multiple stages?

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How do I?? / Re: OLD LATHE
« Last post by celsoari on November 11, 2019, 05:25:54 PM »
Cool, looks like you're off to a good start. Let me see what threads you can cut with your current selection.

In this pic you have a gear on the leadscrew. There should be a spacer behind it that you can remove to have the spacer either in front or behind the gear. Can you swap these around as shown by the arrows?

yes I can swap them back and forth by changing the position of the spacer and gear.
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How do I?? / Re: OLD LATHE
« Last post by Pete. on November 11, 2019, 04:34:29 PM »
Cool, looks like you're off to a good start. Let me see what threads you can cut with your current selection.

In this pic you have a gear on the leadscrew. There should be a spacer behind it that you can remove to have the spacer either in front or behind the gear. Can you swap these around as shown by the arrows?
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How do I?? / Re: OLD LATHE
« Last post by celsoari on November 11, 2019, 03:53:16 PM »
You're doing fine with your English Celso.

If it's a 8tpi screw it's less likely to be of German origin.

What tooth counts do all your other gears have?

 have 16, 18, 32,32, 44, 48,52,56, 60,64,72,80,90,100,127 t.

Ah, now you're talking. You can do metric threads with the 127 tooth gear.

One more question. There is a gear behind the one marked in green. Should be 26 teeth. Can you confirm this?

yes there is behind a 26 teeth gear too
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How do I?? / Re: OLD LATHE
« Last post by Pete. on November 11, 2019, 03:10:01 PM »
You're doing fine with your English Celso.

If it's a 8tpi screw it's less likely to be of German origin.

What tooth counts do all your other gears have?

 have 16, 18, 32,32, 44, 48,52,56, 60,64,72,80,90,100,127 t.

Ah, now you're talking. You can do metric threads with the 127 tooth gear.

One more question. There is a gear behind the one marked in green. Should be 26 teeth. Can you confirm this?

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How do I?? / Re: OLD LATHE
« Last post by celsoari on November 11, 2019, 11:17:20 AM »
You're doing fine with your English Celso.

If it's a 8tpi screw it's less likely to be of German origin.

What tooth counts do all your other gears have?

 have 16, 18, 32,32, 44, 48,52,56, 60,64,72,80,90,100,127 t.
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