[Diy_efi] How to read turbine RPM

[Mike]

>From what I've read on this over the past few years, its not a reliable
means for embedded (in car) application, sure you can do it with a
laptop, pc etc - up to a point and that is issues of filtering and
noise rejection are an issue, especially since the noise is not
of the same character given all the variables, but for an
embedded in car device I am most in favour of an optical method, its
direct and should be possible to have high resolution and accuracy
dependent on a simple crystal oscillator. The question then arises
can an optical method be implemented which doesnt require any drilling
of the housing whilst not impeding airflow (ie. Through mounting a
sensor upstream of the compresor wheel). Personally I dont mind drilling
a small hole in the housing with a plastic window and sealing well
enough to avoid air leaks. A simple microprocessor can then acquire
the pulses in a timer and either send to RS232 or to any display...

rgds

mike



At 03:51 PM 1/7/03 -0000, you wrote:
>You should be able to determine RPM from the sound frequency.  Don't know 
>any formula, but a sound card and microphone should do it. Anyone give us a 
>baseline? is the number of compressor blades relevant?  TomS.
>On Tue, 07 Jan 2003 13:50:03, Mike <erazmus at iinet.net.au> wrote :
>
>> Yeah I like this variant, paint one side white reflective to IR
>> and the other sides absorb IR (black) and a simple reflector
>> type module at right angles - needs a hole in housing but thats
>> a minor issue...
>> 
>> So anyone know of enamel paints with known IR reflectivity
>> constants ?
>> 
>> rgds
>> 
>> mike
>> 
>> 
>> 
>> At 04:43 PM 6/1/2003 -0700, you wrote:
>> >I can't find the website, but I did see where a guy was using an optical
>> emitter/detector and reflecting off the flat of the nut on the compressor
>> end of the shaft.  If I remember right, he tapped a
>> >small hole into the inlet housing to mount the emitter/detector gadget.
>> >
>> >Scott.
>> >
>> >
>> >> > > " For this to work optimally you'll need to use a turbo speed 
>sensor  "
>> >> > >
>> >> > > Would  like to know how to read turbine RPM especailly from non
>> magnetic
>> >> > > compressor / turbine wheels.
>> >> > >
>> >> > > Can you offer any info / links on how it is done.
>> >> > >
>> >> > > Thanks
>> >> > >
>> >> > > Hugh
>> >
>> >
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