Re: repeatable vs accurate switch

Ordinary opto-interrupters are sensitive to temperature, dust,
ambient light, supply voltage and ageing. Don't depend on them for
anything better than +/-0.01".

An optical encoder "index" channel can be accurate to better than +/-
0.05 degrees of rotation.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Don Rogers <Don@C...> wrote:
> I am working on a machine design that needs a signal that is
repeatable to
> a very tight tolerance. I don't care if it trips at 0.250" or at
> 0.000250", as long as it is the same each time. My thoughts now
are
> focusing on optical sensors. First is just a plane flag through an
optical
> coupler, and the second is a mechanical amplified version, IE a 10X
gear
> driven optical aperture.
>
> Any pitfalls or ideas that come to mind??
>
> Thanks Don