Hello from bright and sunny Rochester, New York (near Buffalo, not
so much). I'm a lover of both new and old technology and an admirer
of clever solutions to interesting problems. I especially liked the
idea of measuring the length of paper played and making a conversion
using the ratio of roll distance to wind motor revolutions to figure
out RPM.

So why not just count the number of revolutions for a minute and get
the answer directly -- it ain't called RPM by accident! It's usually
about 100 RPM, so counting it shouldn't be a problem. If you're
impatient, count for 15 seconds and multiply by 4.

On the other hand, this might be a good reason to buy a new tool or
smart phone application.

Regards,
Craig Smith
Upstate New York