piclist 2002\08\12\083318a >
Thread: What Test Gear to measure xtal frequency to 1Hz
www.piclist.com/techref/timers.htm?key=xtal
picon face BY : Mike Singer email (remove spam text)

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Peter Crowcroft wrote:
.
.
> We are using a 12.000MHz crystal in a timer circuit. It has 2
> x 33pF load capacitors and the xtal is under the IC socket
> so the tracks to the uC are 0.15" only.
> We want to measure the osc frequency to within 1Hz so we can
> adjust the load cap in one leg. Can someone tell us what test
> gear we need to be able to do this?
.
.
Peter,
given your "12.000MHz crystal in a timer circuit" capable
of keeping 1Hz stably, you need nothing more, but
precision timer or clock, I think.
Count your timer ticks for a long enough precise time
period and you'll get  the osc frequency.
Then you may use one of your so precalibrated timer
circuits to fill periods of next your timers in order to
speed up measuring process.
You may get precise time signals from "radiostations of
precise time signals" for example.
Keeping 1Hz stably at 12.000MHz crystal is not a simple
task. look at Microchip's DS00588B.PDF.

Mike.


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