What's the easiest way to test unmarked crystals?
Roy J. Tellason
rtellason at verizon.net
Thu Oct 19 23:42:57 CDT 2006
On Thursday 19 October 2006 09:35 pm, Ethan Dicks wrote:
> I have a small handful of crystals and was wondering what the easiest
> way to divine their frequencies... I can say that I'm reasonably
> certain that all of them are between 32.768Khz and 50MHz, but some are
> blank, and some have non-obvious cryptic markings. What I'm looking
> for is some simple way to get them to oscillate and measure them with
> a frequency counter (i.e. - assume one is starting with a working,
> trustable frequency counter).
> Is it as simple as a pair of inverters/NANDs in the classic crystal
> loop, or is that circuit massively frequency dependent (i.e. - works
> for 1Mhz-10Mhz, not faster or slower...)?
I'd go with CMOS, myself -- any inverting gate should do it. Put some
high-value resistance across it to bias it (10M?), and you may need a cap or
two at either end to get the crystal going. Maybe run it off a 9V battery?
I have a bunch I need to test too. :-)
Member of the toughest, meanest, dealiest, most unrelenting -- and
ablest -- form of life in this section of spac, a critter that can
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Information is more dangerous than cannon to a society ruled by lies. --James
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