And for our Next Trick ... How 'bout a diyTrionic?

Raymond C Drouillard cosmic.ray at juno.com
Tue May 5 04:27:35 GMT 1998


I remember this thread from a few weeks ago.  I seem to recall someone
mentioning that around 80V DC is put between ground and the end of the
coil opposite the spark output.  That way, the circuitry doesn't have to
withstand the multi-kilovolt spike of the spark.  If that's the case, it
can only be used with a distributerless system.  The gap in the
distributer would leave you with an open circuit.

Is this what you plan on doing, or are you going to come up with a
circuit that will read a few milliamps of current and still withstand the
big zap?

Ray Drouillard


On Mon, 4 May 1998 19:40:10 -0700 "Robert Harris"
<bob at bobthecomputerguy.com> writes:
>The disadvantage of an acoustical knock detector is that it detects the
>"sound" of knocking, i.e. a certain frequency and type of noise that
>unfortunately can be masked or enhanced by physical engine
charactoristics
>(aluminum, iron etc) and change's frequency etc by many factors and the
fact
>that ordinary engine noise has to be filtered out.
>
>The Ionization Knock Detector looks for a specific event in the
combustion
>gasses - the sudden appearance of ionization products after ignition. 
Since
>this mechanism is not heavily engine material, size, fuel, temp, ambient
>noise dependent for determining its characteristics, the detection of
the
>event is straightforward without the need of highly sophisticated self
>anally extracting make TI rich DSP's.   Start with a clean signal and
you
>don't need the hi fangle BS to make the system work - a strange concept
I
>know but once upon a time was considered the way to do things.
>
>Properly done, ION can work on everything from a lawnmower to a
Multi-staged
>turbo intercooled alcohol fueled road rocket without any basic changes
or
>tuning.  It simply must detect the knock related ionization event -
which
>incidentally will cause a low voltage dc conduction across the spark
gap.
>Simple.  Non computerized, wazoo ized and eminently doable without
anything
>even approaching a DSP.

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