Starter Tooth Sensor Question

[bcroe at juno.com]

Yes, even if a tooth is a bit battered, it only represents
a couple of degrees.  Battered or not, it will not be 
moving into the position of an adjacent tooth.  And the
the shaft runout should be pretty small compared to 
tooth dimensions.  

A PIC ought to do it, if it can match the top RPM rate.  
But I won't be knocking a tooth off it, so something 
else will be needed for sync on the flywheel, and a 
second crude sync from the cam/distributor.

The Hall devices I picked for experiments 
(MLX90217) claim to be self adjusting to things 
including gear wear, rise time of .4 microsecond, 
and 15KHZ bandwidth.  That sounds like they could
do the job.  I understand the OEMs putting a nice 
missing tooth wheel in their engine, but those of 
us trying to upgrade 70s engines just have to make
do with what we have.

Bruce Roe

On Tue, 11 Dec 2001 14:14:08 +1100 Peter Gargano <peter at techedge.com.au>
writes:
> bcroe at juno.com wrote:
> > 
> > Flywheel teeth are not so accurate, but there are so
> > many of them there should be plenty of resolution.
> 
> As well, the angular resolution compared to a much smaller
> diameter distributor or crank wheel should be better - even
> allowing for gross machining inaccuracies.
> 
> > A counter of the same module could keep track of
> > crank position.  But another sensor is needed to sync
> > the thing.  I have some hall effect devices that adjust
> > themselves to the signal level.
> 
> This is the job for a small "intelligent" device like a PIC.
> It can also easily distinguish missing (or extra teeth) easily
> (eliminating a separate sync pickup). Less than US$5 for
> 5 MIPs - amazing!
> 
> Peter
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