crystals

Toothpaste and a flat glass plate grinding brings you up in frequency. If you go a bit too far, pencil lead brings you back down ...within some reasonable limits.

Jim

Crystals seem to have gotten stouter than when I was in my youth -- or I was just worse at handling things then than I am now.

And you need to visit your local hobby shop -- most crystals in 72MHz RC gear are now HC45. And the 72MHz stuff has gone obsolete -- most serious RC gear that's getting sold these days is 2.4GHz, which has whatever crystal size and shape the manufacturer feels like using, with no impetus to make it user-replaceable.

Right, the point being that even with worst-case assumptions, a model airplane crash is less violent to a crystal than falling off a workbench.

Cheers

Phil Hobbs

I'm too lazy to bestir myself at the moment -- but have you looked at data sheets for shock & vibe specifications? Even the stuff intended for cheap consumer goods may have the numbers.

'course, translating that to real-world actions may be a trick (I've been told that putting an instrument down on a hard surface and hearing a "click" means that you've just exposed it to a brief 50-g shock. I suppose I have to believe it...).

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I dropped a little USB flash memory drive from my pant pocket about 3 feet off the concrete ground, and it never worked again.

-Bill

I've seen some slimline pocket disk drive enclosures that were aluminum milled with ZERO clearance to fit a laptop drive mechanism. The resulting case is so tight that it does absolutely nothing to reduce shock on impacts. It was scary (but looked nice on the outside). A bulky plastic case, with maybe some rubber bumpers, is a far better design.

Impact on hard surfaces isn't good for feet/legs, either.

I've looked at numbers - but what do they mean. Using your number for example, what does a typical 50g shock look like? 3 foot drop on hard floor, 3 foot drop onto office carpet A day and a night travelling in a brief case in the boot of a car? I don't know - which is why I am asking.

Sorry I have phrased things poorly. I was aware of the physics of the event - that the G-force was lower for the model.

I guess the question I should have asked is, "how fragile is fragile for a crystal"? What sort of things kill these semi precious stones?

So far the best examples I have are:

And the best advice is:

"handle like eggs"

but I would like more information

Or someone who *knows* that his self worth is not based on appearing to know everything and has no need to put anyone down. This is a time for you to shut up.

"David Eather"

"David Eather"

I fly R/C models. In about 5 crashes (pretty much nose-down), I've had one crystal become a definite problem.

esp. pages 5 & 6. Any relevance?

And 100 - 200 HZ vibration - the mechanical resonance of the structure is bad news.

Great general info. Many Thanks!

Sigh

Yours is a "how high is up?" question. Do you have a specific question or questions? Maybe there could be some numerical answer. Otherwise, the generic answer "shock is bad for crystals" is all you can go by. I don't think there are any units of measure for "fragile". :-(

Ed

Well, when I suggested he look for shock & vibe specifications for crystals on their data sheets, he said "I've looked at numbers - but what do they mean."

So apparently he wants knowledge without having to work for it.