AVR-Chat

On Wed, Dec 31, 2003 at 09:59:56PM -0500, Snowden wrote:
> fnatmed wrote:
> > --- In AVR-Chat@yahoogroups.com, "William Nachefski" 
> > <slaphappysamy@y...> wrote:

> >>I Need a pretty broad range, from say 15,000 rpm to 200,000.
> >>Accuracy doesn't have to be that percise as long as its within a
> >>couple of thousand actuall rpms.  What I meant was With each
> >>complete rotation of the turbine rotar shaft I get one pulse
> >>from the Phototransistor.  So that equates to one pulse to the
> >>M.C. per revolution.  Thanks for the help guys keep the
> >>suggestions comming!

> > The paint doesn't last.  Need a good way to color the nut flats that 
> > will withstand turbo temps.  The light pipes melt.  Need a source 
> > for high-temp lexan or something.

> I guess it would depend on the temp, but maybe powder coating would work.

You may be able to slip a collar over the nut, one that's basically
round with shiny, flat surfaces machine into it to reflect.

A Hall sensor may do the trick as well; less sensitive to getting
dirt on the surface. You should be able to pick up the corners of
the nut as they pass closest to the sensor. Just make sure that you
have good ventilation around the magnet and sensor. Magnets don't
stay magnetic for long when they get too hot.

Of course, one could go back to scratch and look at the acoustics of
blade-passing or roller-bearing frequencies, but getting accurate
numbers is difficult.

Taking the speed reading off the cooler, compressor side should be
obvious for any sensing.

-- 
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
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