The problem with 440 Hz is that "11" ( 440 = 11 * 5  * 2^3 ), so if you
can get a crystal or ceramic oscillator/resonator with a neat multiple
of 11 and 10, you'll probably get 440 Hz.

But 440Hz is for "tempered" (not sure about the name) scale, isn't it?
This A in natural scale is 441,48 Hz. And this difference is noticeable
just for the best ears.

You may try to use a frequency generator and play around 440 Hz to see
if a close enough value from a standard crystal would really sound as
out of tune.

Francisco


Koen van Leeuwen wrote:

>Hi all,
>
>I am now designing a electronic metronome for myself, PIC-based of course.
>As an extra, since I'm using crystal precision anyway, I thought of including a 440 Hz (an A note) reference tone to tune flutes etc.
>But I can't find any standard (cheap) crystal that divides nicely in 440 Hz.
>Do you know a simple solution, that does not introduce audible jitter (that would effectively ruin the use as a tuner)?
>Are self-adjusting timer loops good enough?
>
>Well, thanks in advance again,
>
>Koen van Leeuwen
>
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