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Quartz crystals

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Re: Quartz crystals

#31

Post by jacquesm »

adrian_b wrote: post #30
Animats wrote: post #15

Earlier quoted context omitted.

There are piezo buzzers and beepers, of course.

Yes, but those normally just convert the electrical oscillations to sounds, they are not parts of the oscillators that determine the audible frequency. In the past, audio RC oscillators or LC oscillators were used, with the former being preferred as the latter required too bulky inductors to reach so low frequencies. Nowadays, it is usually simpler to not use any audio oscillator, but to use some microcontroller that…

Those can make sounds at other frequencies but they are very loud on their resonant frequency. Loud enough to damage your hearing if you're unlucky.

Re: Quartz crystals

#32

Post by gtsnexp »

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…

This awesome. Could you perhaps remember the title of the book you lost?

Re: Quartz crystals

#33

Post by afandian »

adrian_b wrote: post #29
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.

Adding solder has also been frequently used to correct the resonance frequency of quartz crystals that have been ground too much, and I mean during industrial mass-production, not only in a home-lab setting.

How are people sticking stuff to quartz? I know less than nothing, but the pieces of quartz you find in rock don't look like they'd take a solder bond.

I'd assumed that with piezo crystals etc there was a mechanical connection rather than an electrode bonded to the crystal?

But if you can add solder presumably there is some kind of molecular connection with the metal?

Re: Quartz crystals

#35

Post by afandian »

jacquesm wrote: post #26
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.

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/

Re: Quartz crystals

#36

Post by jacquesm »

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/

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

Re: Quartz crystals

#37

Post by jacquesm »

afandian wrote: post #33
adrian_b wrote: post #29

Earlier quoted context omitted.

Adding solder has also been frequently used to correct the resonance frequency of quartz crystals that have been ground too much, and I mean during industrial mass-production, not only in a home-lab setting.

How are people sticking stuff to quartz? I know less than nothing, but the pieces of quartz you find in rock don't look like they'd take a solder bond. I'd assumed that with piezo crystals etc there was a mechanical connection rather than an electrode bonded to the crystal? But if you can add solder presumably there is some kind of molecular connection with the metal?

There is already a silver patch bonded to the crystal where the wire connects to. Adding weight to that obviously will not make the load curve any better but if you do it with just enough to drop you back down below where you wanted to be then it can be a saving move. You could also put a trimmer in parallel, but that might not have enough range (and can also end up overloading the crystal so the oscillator won't start).

Re: Quartz crystals

#38

Post by adrian_b »

afandian wrote: post #33
adrian_b wrote: post #29

Earlier quoted context omitted.

Adding solder has also been frequently used to correct the resonance frequency of quartz crystals that have been ground too much, and I mean during industrial mass-production, not only in a home-lab setting.

How are people sticking stuff to quartz? I know less than nothing, but the pieces of quartz you find in rock don't look like they'd take a solder bond. I'd assumed that with piezo crystals etc there was a mechanical connection rather than an electrode bonded to the crystal? But if you can add solder presumably there is some kind of molecular connection with the metal?

Electrodes are deposited on the crystal in vacuum, e.g. by metal evaporation or sputtering, in the same way as they are deposited on the semiconductor crystals used to make transistors or integrated circuits.

The electrodes may consist of multiple layers, a base layer that adheres strongly to quartz and a top layer that is solderable, e.g. made of nickel or silver.

The pins of the package that hosts the crystal resonator are soldered on the electrodes, in places well chosen so that they will not damp much the oscillations of the crystal.

When the mass of the crystal must be increased to shift the resonance frequency, excess solder may be deposited on the electrodes.

Re: Quartz crystals

#39

Post by adrian_b »

pfdietz wrote: post #27

I remember when I worked at Motorola some decades ago, there was a little section in the factory area in Schaumburg that made quartz crystals. It's all long since been sold off (I think all the equipment went to China) but I remember all the signs for cyanide alarms, presumably due to some step in the manufacturing process. The quartz crystals themselves were grown with carefully controlled levels of specific impurit…

They may have had baths for galvanic deposition of silver. Those typically used cyanide solutions.

Galvanic deposition of silver has been frequently used for increasing the thickness of thin metal layers that had been deposited in vacuum, in order to adhere to the crystal.

Re: Quartz crystals

#40

Post by gosub100 »

speakspokespok wrote: post #7

With a crystal of the right dimensions and correct input voltage could one feel the crystal vibrating?

And a similar question: if you took a normal magnet and rotated it very quickly, say 10k rpm, would it emit an RF signal at (10k/60) hz? I'm 95% sure the answer is yes but I've never seen this demonstrated.
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