> A pot would probably work but for piano practice my daughter
> says that she has to be able to set the metronome to an EXACT
> speed, and it would seem like an analog pot would be kind of iffy
> for  that.

10-turn pot and a 100MHz Scenix. Not perfect, but 10ns resolution
is getting there

Seriously though, an accurate 4Hz (240bpm) would be easy to get
with a normal decent carbon pot, with the granularity of the PIC's
clock in a timer routine. Without a display the problem you'd have is
repeatability. Perhaps even use tables and a keypad and dial up the
required bpm frequency. Would be more easily and accurately settable
than with a pot, so the LCD might not be strictly necessary, but nice
for feedback. People like feedback. Saleable too I'd have thought, if
someone's not already doing it. There's already at least one on-line

http://www.metronomeonline.com/

Google for metronome and you'll find all kinds off downloadables

Turn it around on her - put pressure sensors on the keys and give her
a mild (at first) jolt when she deviates from the metronome by 0.1%,
she reckons she's the big cheese when it comes to timing ;-)

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