> Fred said:
> RPM should be the most suspect of all. Convenient to think digital is
> more accurate, but you can't just count pulses - accurate to within
> parts per million, but at even 50RPM resolution, the display update
> rate is unacceptable. Other approaches then become dependent on
> mechanical and other issues in the stator ass'y from whence come the
> pulses, with accuracy attainable with $$, unless the higher price is
> just more profit. Same for analog gauges. Digital RPM checkers which
> read optically are very accurate and affordable. Borrowing or buying
> one of these is arguably a must! Or a freq counter from Radio Shack
> and do the math.
It is possible to construct a digital tacho that has better than 50
RPM resolution and an update time of no more than 0.25 second using
about 20 quids (30 euros/dollars) worth of components.
That said, I agree with the view that an analog tacho is easier to
read. Pity the stability of the Rotax units is so poor.
Cheers,
Mark
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