Pic Dude wrote:
> The 131.072 f/$1.77 is the one I am using (I just rounded
> off to $2).  I hadn't run across the $0.64 4-mhz units,
> but that doesn't solve my problem, as I'm also trying to
> stay within the FCC 1.705Mhz limit.  1-Mhz is what I
> really need or even 1.544Mhz.

You're right - the 1 MHz crystals from Digi-Key are indeed horribly
expensive. You can do better elsewhere - about $5 at Jameco, for example
- but that's still steep. On the other hand, a 1 MHz oscillator MODULE
isn't all that bad - about $3 at Digi-Key, or $2.24 at Mouser - so that
might be the way to go. Besides, it gets you back an I/O pin on some
PICs; with an external clock, you need only one pin instead of two.

There are two reasons that 1 MHz crystals are expensive. First is that,
due to physical constraints, it's a difficult frequency to make a
crystal for; you need a big chunk of quartz. (The huge 100 KHz crystals
that used to be used in calibrator circuits had the same issues, but
magnified. The tiny 32 KHz crystals that you see nowadays use a
different mode of operation that isn't suitable for a frequency as high
as 1 MHz.) Second is that they are mostly made for calibration circuits,
so the crystals that you can get are mostly high-precision parts, and
you're paying extra for that.

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