Knock Sensor.

[Bruce Plecan]

> One circuit published in a flying magazine years ago just added
> an op amp onto the standard Bosch Knock Sensor.

Could you possibly scan, or verbally recount that circuit?.

> I
> also recall an article (from Motorola I think) about actually doing a
> spectrum analysis to determine what was engine noise and what was knock;
> it's a very narrow frequency where knock occurs but unique to the engine.

That's a very common error in my book.  While the most often, or most
damaging might be in one area, the are other places that it can occur
undetected and do as much damage.

> I also recall that SAAB only reduced timing on the cylinders that were
> causing the knock whereas the circuit I designed just did a blanket
retard.

But, that means a huge step, ie a cam reference signal
Bruce

> However,  since the 100HP Honda's never had the knock sensor attached we
> never tested it in real time.  All we did was tap the sensor on the block
> while the engine was running and watched the timing retard for a number of
> strokes.
> Cheers,
> John

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