AVR-Chat

--- 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!

How is the turbine blade assembly attached to the shaft, and what 
are you using to actually trigger the phototransistor ?

In my case, the compressor wheel is topped with a regular nut.  I've 
painted the flats of the nut in alternating white and black, so 
there are 3 pulses per rev.  I originally tried pointing directly at 
the blades themselves, but that wasn't consistent enough.

I'm using plastic light pipes to send a white LED light to the nut, 
and to read the reflection back.  Problems though ...

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.

Dean.