Knock sensors

[swagaero]

Frank F Parker wrote:
> 
> > I thought I'd get a cheap equalizer (i.e. one that's lying
> > around -- free) and use the above-mentioned RatShack audio
> > amp to listen in on the engine whilst tuning out the stuff
> > I don't want to hear -- until I read Probst's book.
> >
> > "some day", but now we're getting serious.  I don't want
> > to drive around with a spectrum analyzer lying on my floor
> > board -- I can whip up a notch filter and drive an analog
> > meter (or, for that matter, an AGC circuit that has a lower
> > frequency into it so that I can *hear* some feedback).
> >
> > Sorry for the rambling .... has anyone done anything like
> > this.  Todd Knighton, and some others, keep knocking me (pun
> > intended) to get the commercially available knock detector
> > (don't remember who by at the moment  ....  J&S  ?? ) -- but it's
> > like $400, as I recall .....
> > Tom Cloud
> 
> Tom,
>  I have done what you thought about with an equalizer and knock sensor
> and it was not much better than just listening to bare sensor.
> Todd and the others are correct-simple analog filters just do not
> cut it- that is why the early knock systems were so sensitive to
> location etc. The J&S Electronics unit uses DSP filtering so you are able
> to filter freq that are separate but close together- impossible even
> with multiple pole analog filters. Best the J&S has a 0-1.25 volt
> monitor out so you can drive a LM3914 for a retard display. I also ran
> it to a datalogger and took data at 50/sec along with various pressures
> and temps on a recent turbo project car.
> 
> This is one of those cases where there is not a cheap way to monitor
> and control knock- gotta pay your bucks!- Even then location of sensor
> is important to the best performance.
> 
> Regards,
> 
> Frank Parker
> fparker at umich.edu
> Motorsports Data Acquisition
> >
> >



Next tuesday I will put a schematic for a visual knock detector 3 led's
ect free for the building it's just another one of my (well it works but
no one wants to buy it)

Steve
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