Knock alarm

[Tony Cooper]

David Piper wrote:
> 
> Can someone comment on the availability of a knock sensor alarm.  Which
> sensor would have universal applicability?  How could I fab a circuit to
> count the freq and intensity to generate an analog sig of
>  0 - 5V for data acq and recording.  Or just amp the sig into a LED for
> driver observation.  The sensor is a 5KHz piezo xtal, I think.  What is
> the best location for portable use on a dynojet?
> 
> Thanks
> TurboDave
> 
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You may have a problem here. 
The sensor sounds about right, but you will have a problem making a
generic system. 
All engines knock at different frequencies - no 2 engines are the same.
What you need is
some intellegence built into the system, something like a DSP would do
the trick, but even then
the system may need some 'tweaking' just to get the correct frequency,
and that would only
ever work on that engine. Even aging can move the frequency of knock.

Sorry to be so negative
Tony.

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