I remember from my RC days that the commercial tachs for airplanes could be
used a few inches away.  They also read light through the prop, not reflected
from it.

Geoff Child wrote:

> I am making a no contact tachometer using a pic for a model airplane and am
> trying to find a reflective sensor for the pickup. The ones that I have
> looked at have to be to close ~.150 inches and I would like to be several
> inches away. Does any one know of any any sensors?
>
> Thanks
>
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