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Quartz crystals

pa3fwm.nl

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Re: Quartz crystals

#51

Post by hilbert42 »

afandian wrote: post #35
jacquesm wrote: post #26

Earlier quoted context omitted.

Oh that is so cool. I played the one in Liepaja, Latvia for a bit and it was absolutely amazing. It's love/hate for me (like the harpsichord), I love the instruments but I usually do not like the music that is played on them because of the grating effect. I have pretty bad tinnitus which really spoils a lot of music for me, extremely annoying.

Wow! I'm working on something much, _much_ smaller than that! https://blog.afandian.com/tags/harmonium/

Ha-ha, I didn't read this until I'd written the above reply, seems we have something in common.

Incidentally, I'm one of those mad people who'll put on a recording of Helmut Walcha playing Bach's Passacaglia and Fugue in C minor on a Silbermann and turn the volume up until the room shskes.

Re: Quartz crystals

#52

Post by hilbert42 »

gtsnexp wrote: post #50
hilbert42 wrote: post #49

Earlier quoted context omitted.

Could well be either, it was around the late 70s early 80s when the book went walkabout. Damn nuisance my memory isn't better. However, I'd recognize it instantly if I saw it. Must check those references out. There may be enough info online for me to figure it out. Thanks.

Thank you!

"Crystal Oscillator Design and Temperature Compensation :Marvin E. Frerking (1978)."

Ah, that has to be the book, just did a search and there's a photo of the cover on Amazon that I recognize. I said it was bright yellow with red writing and I was pretty close with its red lines and bits.

240 pages and not 300, but that's not too bad after close on 50 years. And I was correct about the price too, it is expensive, Amazon has it at $110 for the hardback.

Good one!

Re: Quartz crystals

#53

Post by jadbox »

jacquesm wrote: post #20

Nice to see this get more love, I had a fun time going through that site, there are lots of gems there. For instance: https://www.pa3fwm.nl/projects/sdr/ The longer you read, the more amazed you will be.

Dang that fascinating but way above my head. I need to take a few classes in signal processing I think to parse what's all going on here.

Re: Quartz crystals

#54

Post by afandian »

hilbert42 wrote: post #47
afandian wrote: post #23

Earlier quoted context omitted.

I've just spent the weekend tuning brass reeds from an organ. It sounds like a very similar process, except you can grind both ends of the tongue to raise and lower frequency. And, if you're sneaky, you can add solder.

Funny you should mention that another hobby of mine was rescuing old harmoniums and making them playable again—you know, fixing and replacing reeds, renewing bug-eaten felt, sealing rat holes in the bellows, etc. I grant you it's not in the same league as voicing a diapason though. :-) I reckon adjusting and tweaking things goes with the territory. I'm pretty much at home tweaking crystals, fixing reeds, aligning IF…

That's exactly what I'm doing! Nothing grandiose.

https://blog.afandian.com/tags/harmonium/

By 'repaired' you mean closing a fracture? I'm interested to hear your experiences! Electronics solder or silver solder?

This one is 60 cents sharp across the board (not uncommmon), but I wanted a social instrument. So I brought them down with solder. The bottom two octaves have worked out well. The next two... we'll see. I now have the fear that I've weakened the brass by heating it. But it still sounds nice and speaks well. Fingers crossed.

Re: Quartz crystals

#55

Post by gtsnexp »

hilbert42 wrote: post #52
gtsnexp wrote: post #50

Earlier quoted context omitted.

Thank you!

"Crystal Oscillator Design and Temperature Compensation :Marvin E. Frerking (1978)." Ah, that has to be the book, just did a search and there's a photo of the cover on Amazon that I recognize. I said it was bright yellow with red writing and I was pretty close with its red lines and bits. 240 pages and not 300, but that's not too bad after close on 50 years. And I was correct about the price too, it is expensive, Ama…

Fantastic! Also found used on abebooks! Thank you

Re: Quartz crystals

#56

Post by hilbert42 »

hilbert42 wrote: post #41
hilbert42 wrote: post #9

The article is a nostalgic reminder of when I was first interested in electronics and got interested in quartz resonators for projects. Grinding down old war surplus FT243-style crystals and other types so as to resonate at frequencies I needed was a common practice with hobbyists back then. I used many similar techniques to the same end of removing quartz which raised its frequency. Grinding materials included abras…

Heavens, that should be AT cut not XT. What on earth was I thinking of? Some of you guys should have picked that up. ;-)

Further to my unforgivable boo-boo. This article provides a pretty good introduction to the subject and there's a diagram of a quartz crystal at the beginning indicating the position of AT cuts in relation to the crystal and other cuts.

I've seen much more detailed diagrams of the crystal and cuts/cutting angles but I can't find one online. . Those precision diagrams are required by those who cut the quartz at the start of the manufacturing process.

https://xoprof.com/2023/09/unleashing-the-mystery-of-crystal...

Re: Quartz crystals

#57

Post by hilbert42 »

afandian wrote: post #54
hilbert42 wrote: post #47

Earlier quoted context omitted.

Funny you should mention that another hobby of mine was rescuing old harmoniums and making them playable again—you know, fixing and replacing reeds, renewing bug-eaten felt, sealing rat holes in the bellows, etc. I grant you it's not in the same league as voicing a diapason though. :-) I reckon adjusting and tweaking things goes with the territory. I'm pretty much at home tweaking crystals, fixing reeds, aligning IF…

That's exactly what I'm doing! Nothing grandiose. https://blog.afandian.com/tags/harmonium/ By 'repaired' you mean closing a fracture? I'm interested to hear your experiences! Electronics solder or silver solder? This one is 60 cents sharp across the board (not uncommmon), but I wanted a social instrument. So I brought them down with solder. The bottom two octaves have worked out well. The next two... we'll see. I no…

"By 'repaired' you mean closing a fracture?"

Right, I haven't had many fracture but it was more than I expected. I've had some come apart (completely—shear off). One I recall fixing (replacing the reed) with a piece cut from a phosphor bronze shim several thou thick (I had various thicknesses). Replacing the reed was easy but voicing was a problem because p-bronze has different properties to the original. It was a long while ago so I can't remember exactly what I did but it worked—sort of. I eventually got it roughly in tune but it was a different volume to the others.

About two weeks ago I was up at my old family home for the first time in years and there are two harmoniums dating from the the mid to late 19th C. which I meant to fix years ago. The woodwork on one is particulary ornate and in excellent condition. They both have dead keys when I played them. Reckon I've some wok cut out for me. .

Re: Quartz crystals

#58

Post by jacquesm »

afandian wrote: post #43
jacquesm wrote: post #36

Earlier quoted context omitted.

You are going to be leveling up in a whole bunch of skills.

Yes! Most important being calibrating what I should and shouldn't attempt yet.

I would just attempt it all and see where you get stuck. But one step at the time with total focus on that one step. I've done a lot of instrument repair over the years and the first one of a new class is always the hardest. So rather than to take the whole thing to pieces I'd fix just one aspect of it, reassemble and enjoy the improvement. Then fix the next thing. It's much more work than stripping the whole thing down but it keeps the gaps in your understanding small enough that you won't end up with a pile of parts rather than an instrument.

I've been trying to remember the name of a particular instrument for you for the last 24 hours but so far no success, if I recall it I will post it here.

Re: Quartz crystals

#59

Post by afandian »

jacquesm wrote: post #58
afandian wrote: post #43

Earlier quoted context omitted.

Yes! Most important being calibrating what I should and shouldn't attempt yet.

I would just attempt it all and see where you get stuck. But one step at the time with total focus on that one step. I've done a lot of instrument repair over the years and the first one of a new class is always the hardest. So rather than to take the whole thing to pieces I'd fix just one aspect of it, reassemble and enjoy the improvement. Then fix the next thing. It's much more work than stripping the whole thing d…

Thanks! That's the approach I'm taking. Bellows airtight first. Then a period of reflection on the tuning before the next step.

The good thing about harmoniums is that they have clearly defined layers, and each layer can be approached left to right.

The things that worried me were the steps that are difficult to reverse without the risk of damage, like gluing and tuning. I've done some of both now!

Curious about that mystery instrument. Give me a clue.

Re: Quartz crystals

#60

Post by jacquesm »

afandian wrote: post #59
jacquesm wrote: post #58

Earlier quoted context omitted.

I would just attempt it all and see where you get stuck. But one step at the time with total focus on that one step. I've done a lot of instrument repair over the years and the first one of a new class is always the hardest. So rather than to take the whole thing to pieces I'd fix just one aspect of it, reassemble and enjoy the improvement. Then fix the next thing. It's much more work than stripping the whole thing d…

Thanks! That's the approach I'm taking. Bellows airtight first. Then a period of reflection on the tuning before the next step. The good thing about harmoniums is that they have clearly defined layers, and each layer can be approached left to right. The things that worried me were the steps that are difficult to reverse without the risk of damage, like gluing and tuning. I've done some of both now! Curious about that…

I've found it! The 'clue' was that the name contains 'lion' but I still couldn't find it and then suddenly it popped up. Pedalion.

They are fairly big compared to your typical harmonium.

https://www.reedsoc.org/index.php/rosdb/vieworgan?ascnd=1&ID...

They're a funny half breed, they have a blower motor, use reeds instead of pipes, and were popular with churches as practice instruments.

Oh, and this might interest you if you haven't found it yet:

https://www.reedsoc.org/index.php/information/reed-organ-rep...

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