Electronics > Beginners
How read the frequency of crystal
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Andbro:
Hi,

How measure the crystal frequency in circuit ?

Thanks
ataradov:
If it is a working oscillator circuit, then put an oscilloscope probe on one of the pins and observe the waveform. Use 10X probe to minimize the load.
magic:
Use a 100x probe to minimize the load >:D
10x ones have input capacitance similar to typical crystal capacitors.

That being said, 10x will work too but frequency will change some fraction of a percent when the probe is connected. Ideally, you would try to measure the resulting clock rate of the whole IC rather than the oscillator directly.
ataradov:
Well, in practice I never had a problem with 10x.

It also depends on what you mean by "read". If you just need to figure out if it is 8 MHz or 16 MHz crystal, then 10X is plenty.

If you want to actually determine the frequency, your setup may get rather complicated depending on the required accuracy.
james_s:
Or use a frequency counter, that's kind of what they're designed to do.
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