What sort of signal is the knock sensor?

[Ward]

GM has several differnt freq's, depending on application, and the media,
they do have a few "dry" sensors. 6.?Khaz is the most populat for V8's.  The
internal spring is the resonat element.

Ward

On Tue, 23 Nov 1999 16:48:37 -0600, Don.F.Broadus at ucm.com wrote:

> I 'm using a 1.5 inch threaded pipe (1/4 inch NPT)  I removed the pipe
and
> butted the  sensors together. This did not provide enough coupling to
> trigger the ESC. I don't have any more NPT pipe so  I then filled the
pipe
> with ultrasonic coupling fluid to see if the cavity was resonating. 6KHz
was
> still the sweet spot although a little quieter now.  I believe each det
> sensor being a peizo transducer has been tuned like a quartz crystal at a
> certain freq. (6KHZ)  By using two  DR 562 sensors they both are in
> resonance at 6 KHZ. I need to find more det sensors as I only have one of
> certain types right now. The DR 562 is by far the easiest to find being
used
> on V8's , V6's four's carbed and injected. I'm looking for Quad  4
sensors
> to test believing that they will be tuned  higher to mask the bucket
tappets
> and chain noise.
>                                                  Don  
> 
> > -----Original Message-----
> > From:	jsg at donet.com [SMTP:jsg at donet.com]
> > Sent:	Tuesday, November 23, 1999 3:59 PM
> > To:	gmecm at efi332.eng.ohio-state.edu
> > Subject:	Re: What sort of signal is the knock sensor? 
> > 
> > | By using the output of a HP3324A function generator connected to  DR
562
> > | knock sensor coupled with a 1/4 pipe to another DR 562 knock sensor I
> > was
> > | able to track the freq. curve of the sensor. The sensor responds to
> > 
> > <delete>
> > 
> > | with a scope the DR 562 sweet spot was 6KHZ. A loud tone could be
heard
> > at
> > | 6KHZ indicating resonance.  7-10KHZ had good outputs. The voltage
> > dropped
> > | off at 12 KHZ . An output was observed up to 50KHZ very small
amplitude
> > 4
> > 
> > Don, is this a resonance of your test setup or of the sensor? (i.e.,
> > if you double or halve the length of pipe, does it stay the same?)
> > 
> > john gwynne





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