counting teeth

["Ed & Marsha Prytherch" <mred2u@domain.elided>]

Counting flywheel teeth instead of one trigger per revolution gives better
resolution or update time. Tachometers count the number of plulses in a
preset time and divide one by the other to get rpm. If there is only one
pulse per rev, then the count time must be a lot longer than if there are
multiple pulses per rev. You may see a noticeable delay and/or larger jumps
in rpm readout if you have a one pulse per rpm setup.
Ed Prytherch

Russ wrote:
>       I just wonder how or why the tach counts the flywheel teeth.  There
are 131 to count for each revolution whereas counting only one trigger per
revolution would be easier even for a computer.
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