HOWTO Determine Unknown XTAL Freq

Good day.

I recently removed some crystals from some old electronic devices but do not know what frequency they are.

Is there an easy and accurate way to determine their freqs?

Thank you.

-Tim

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news.cogeco.ca
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"news.cogeco.ca"

** Try reading the labelling.

Nearly all crystals are printed or stamped with their frequency in MHz.

....... Phil

Reply to
Phil Allison

What sort of equipment? That may tell us a lot. IF TVs for example, the Color Burst Crystals are one frequency. If from say computers - there are others used. Aside from that - they're usually stamped and if you can't make them out - then a crystal tester with associated readout device would help.

Reply to
Radiosrfun

I'm assuming you don't have an oscilloscope? You might be able to use one at your local high school. If just hooking up the test leads doesn't start it oscillating, get it going with a 9V battery through some safe resistance, at least 10K probably.

I don't know anything about your electronics background, but if it's an option, and you don't have access to a scope, you could build a simple circuit with a PIC microcontroller and hook the crystal to it; then program a delay loop and flash an LED with some fraction of the crystal frequency. I don't know offhand what would happen if the crystal frequency were too high for the uC though. Probably nothing destructive, but you wouldn't get the correct reading. I'd get my hands on a scope if I were going to do much messing with crystals anyway. I've seen them pretty cheap on eBay but of course the shipping charges will get you.

Reply to
jcomeau_ictx

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Reply to
John Fields

LMAO!!!!!!!!!!

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Dave M
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Reply to
DaveM

a 4060 or two might be more convenient than a UC for this task.

Bye. Jasen

Reply to
jasen

It might, especially with a solderless breadboard. The basic idea is to make the invisible visible, and how you do it depends mostly on what you have available. My preference would be to use a microcontroller, since I'm more familiar with them, and changing the delay loop is just a matter of a few lines of assembly code rather than changing wiring. The last time I used a counter chip (a 4040) was

13 years ago:
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What I don't know, not having a scope available, and never having played much if at all with crystals, if a scope probe will start a crystal oscillating by itself, or if a voltage needs to be applied across it. I just bought one on eBay so I guess I'll find out in a few days.

Reply to
jcomeau_ictx

"jcomeau_ictx"

( snipe mindless drivel)

** FUCK OFF - Bloody Google IDIOT !!

....... Phil

Reply to
Phil Allison

Sounds like someone could use a beer.

Reply to
jcomeau_ictx

Yes. There are many easy and accurate ways to determine the frequency of a crystal. They require some test equipment though. Rather than have the group guess what you have and to what lengths you might be willing to go to determine the frequencies, why not give us some more information?

I assume that if you had any of the equipment that would be needed, you would not be asking the question, and I strongly suspect that your curiosity about the crystal frequencies is not commensurate with the expenditure of time and money necessary to quench it.

Correct?

Chuck

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Reply to
Chuck

What he's trying to tell you, in a nice way, is that it seems that you don't know what you're talking about.

You see, there are two things you could be referring to: a crystal or a crystal oscillator.

If it's the former, then before it can be made to oscillate it must be surrounded by circuitry which will force it to oscillate. Neither putting a scope probes across it nor placing a DC voltage across it will cause it to oscillate.

If it's the latter, then it's a "crystal oscillator" not a "crystal" and it will contain the crystal and the circuitry needed to make the crystal oscillate when it is supplied with the proper supply voltage, not by putting a scope probe across it.

Go here for a clue:

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JF
Reply to
John Fields

Thanks for the edification. I thought I made it clear that I was guessing.

Different newsgroups have different cultures, and I'm not familiar with this one yet. comp.lang.forth, for example, usually makes a reasonable attempt to answer the OP's question before degenerating into ad hominem attacks and other vicious sniping. Live and learn.

I still think the uC approach might work, but I have to dig up another crystal to make a quantitative comparison. I'll post when I have something concrete to offer.

Reply to
jcomeau_ictx

"jcomeau_ictx"

** Go shove your

FUCKWIT GUESSES UP YOUR ARSE !!

CRAWL BACK UNDER YOUR ROCK

You pathetic, asinine Frog Fuckhead

........ Phil

Reply to
Phil Allison

"Chuck"

** Like reading the labelling on the damn things.

Wake up - the OP was some kid trolling.

....... Phil

Reply to
Phil Allison

Once again, Phyllis raises her ugly head and howls:

Ignorant little Aussie bitch. Some crystals are marked with channel numbers, stock numbers, receive frequency where you don't know the offset for the IF, or even unmarked after the PC board is unwashed. Turn off the computer and take your hormones.

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Reply to
Michael A. Terrell

"Michael A. Terrell Psychotic Autistic FREAK"

** Up to the OP to post that sort of info.

Since he has not come back, he is most likely a troll - or he read my post, opened his eyes & realised the frequency WAS written on the damn things.

Either way -

YOU can go a shove your pointy head up a dead donkey's backside where you normally hide it.

CUNT BRAIN !!

....... Phil

Reply to
Phil Allison

Thank Agent for killfiles....

***PLONK****

Peter

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Reply to
Peter A Forbes

"Peter A Fuckwit Forbes"

** ROTFL !!

What a FUCKING MORON !!!

....... Phil

Reply to
Phil Allison

Hm, looks like you need to run for another kook award, Philbert.

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Lionel

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