Turbocharger RPM Measurement for a Beginner

blakeingilroy

I have have little to no experience with electronics but I have a situation that I'm hoping Parallax can help me with. I am in the final stages of making a jet engine out of a common turbocharger, but I need help measuring RPM. I have heard that in some combination between a Basic Stamp Board, an LCD Display, and fiber optics I can fix the problem, but I have no idea what to do. Please help me out.

Mike Green

Can't help you with the fiber optics part, but, assuming you have a shaft involved, you can place a mark on the shaft using a dark matte paint and shine a light on the shaft, then use a phototransistor to detect the light reflected from the shaft. You'd need a detector of some kind (like a comparator) to convert the voltage output from the phototransistor to a logic signal which could be counted using the Stamp's COUNT statement, then displayed on the display.

Jonathan

To add to Mike's suggestion above, I would add a schmitt trigger(like a 74HC132) on the output to sharpen the pulse. Also, what RPM are we talking? A stamp may not be fast enough.

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LilDi

Hall effect sensors work really well when placed close to ferrous gear teeth. If there is an exposed ferrous gear on the turbocharger, the sensor with a Basic Stamp·can count the gear teeth as the gear rotates and the Stamp can convert the teeth count per second to RPMs

http://www.parallax.com/detail.asp?product_id=605-00005

blakeingilroy

Hey Mike Green. Thanks for the info, but can give me some model numbers?

Eric R

blakeingilroy said...
Hey Mike Green. Thanks for the info, but can give me some model numbers?

Mike is dead on with his comment. Most people in your situation use the compressor nut for the counter. Paint the nut black and clean off one side (flat). Don't remove the nut, just remove the compressor housing to do your work. You could try the Parallax infra red as it might work well. Just drill two holes in the inlet of the compressor housing, one for transmit and one for receive directly inline with the·nut. As the flat passes it will refract.

What·is your rpm, 100k? Dont get greedy, parts will fly with the force of a 357 magnum.
The frequency counter on a·Fluke works well also.

That is a great project. you know it will lead to a bigger turbine. I have owned a Solar Titan, Boeing 502-11 and a Rolls Royce Nimbus.

Chris Haley

I used a Banner high speed fiber optic sensor for my turbine project. It was a 24VDC unit. I don't know if they make a 5 volt logic uint. I used a frequency meter to determine my RPM. I an not sure how fast the stamp can count. I was measuring close to 150,000 RPM's. If you would like I can get the Part #. I t was around 130 dollars with the fiber optic probe I purchased. I also have several schematics using an IR emitter and reciever from Radio Shack. I painted the nut half gloss white and haly flat black. It worked perfect but I did not use a stamp for the project. If your turbine is a larger unit you won't turn the RPM's I did. The cycles per second @ 60,000 RPM's would be 1000/Sec. I don't know if the stamp can count that fast or not. I would like to know myself. Good luck on you turbine project, they are a lot of fun. Just keep in mind that the size of the compressor and turbine wheels are a determining factor to your max RPM's

Chris

Chris Haley

You can divide the voltage with a few resistors and/or a zenor diode.

blakeingilroy

Thanks Chris! Could you get me those schematics?

Chris Haley

Sure, Let me find the schematics and the Banner info.

Chris