oscillator voltage

Other Hardware General Electronics
21

Hu justjohn!

What (if you don't mind my asking) is the advantage of this crystal over the 'regular' kind that uses 22pF (ish) caps to tune it? If I were looking to improve the inherent timekeeping of an oscillator, I'd start by looking at some of the 'cheapie' atomic oscillators, for example the rubidium clocks they have on ebay for a few hundred dollars.

22

CrossRoads,

CrossRoads:
Good crystal for '328Ps:
16MHz Crystal HC49US - dipmicro electronics
Don't forget 22pF caps.
22pF/50V Radial Ceramic Disc Capacitor - dipmicro electronics

Thanks. I agree that those are some of the best, at least I always thought so. I've used a LOT of those, but am working on a very small, compact board that needs something a lot smaller.

Paul,

Paul_KD7HB:
Quartz crystals will fracture if the voltage is too high. In vacuum tube circuits back in the 1930-1940, etc. They were used with 300-400 volts, but were an inch square and perhaps 1/16 inch thick.

The crystals you buy today are tiny both in area and thickness. Open a can and take a look.

I should also add the crystals can vibrate in different modes. Look it up!

Thanks! I already knew that they were thin, but for some reason never thought about them breaking. Great to learn some of these things that I "should have" already known. Really interesting stuff about the large crystals!

Allan,

allanhurst:
Too much power risks breaking the piece of quartz or de-bonding the contacts.- it is, after all, vibrating.

I'd stick to the specs.

If you're using it on a '328 , I woudn't worry. The power involved is very tiny.

Thanks Allen! As I mentioned to Paul, I never thought about them breaking. Also, FWIW, I wasn't planning on doing anything except what was in the specs, all of this was just about learning more about them. I seem to recall a video of someone pushing a 328 to 65MHz while cooling it with liquid nitrogen. Not sure, but I seem to recall him showing the speed on a scope and that there was a lot of jitter. Not sure if it was just a poor quality crystal, or if the drive circuit inside the 328 was beginning to do some weird things with a crystal it wasn't meant to deal with.

Hi ChrisTenone,

ChrisTenone:
Hu justjohn!

What (if you don't mind my asking) is the advantage of this crystal over the 'regular' kind that uses 22pF (ish) caps to tune it? If I were looking to improve the inherent timekeeping of an oscillator, I'd start by looking at some of the 'cheapie' atomic oscillators, for example the rubidium clocks they have on ebay for a few hundred dollars.

Thanks. As I mentioned to someone else just now, it's due to limited space. Ha, ha, about the "atomic oscillators." :slight_smile: I doubt I'd ever use anything like that, and in fact wasn't even aware such things existed.

23

justjohn:
... but am working on a very small, compact board that needs something a lot smaller.

I thought you said you were, "just curious".

24

aarg:
I thought you said you were, "just curious".

That's right. The crystal I mentioned in the beginning is one I was thinking about using as I mentioned in the beginning. This whole discussion has been concerning me (and maybe others too if also curious) finding out more about crystals in general, why, because "just curious," if I even used those words in the context you seem to be thinking. :slight_smile: