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Subject: Re: How do i measure signals without affecting them ?
Date: Wed, 20 Nov 2002 19:49:18 +1100
Organization: Lucent Technologies, Indian Hill
References: <firstname.lastname@example.org> <9GHC9.email@example.com>
X-Newsreader: Microsoft Outlook Express 6.00.2720.3000
> you have a very ambitious project!
I like to keep things interesting.. lol.
> cruise control to my Peugeot 406, without any wiring diagram of the cars
> electrics. To find a AC/pulse signal that is related to the speed of the
> car or the engine rpm I used an oscilloscope. Finally I found a signal
> was usable
I basically rewired my engine bay and know what all the wires are. Not to
mention im lucky enough to have a full wiring diagram for all parts.
Unfortunatly im not lucky enough to have a CRO. :(
> turned out to be electrically VERY noisy.
I was thinking i would need some sort of notch filter or something for
analogue signals and maybe the use of a schmitt trigger to actually
recondition digital signals. But as you said above, i think i will need to
get my hands on CRO before i can actually start to build something a little
higher grade than homebrew dodgy brothers circuitry.
> disturbances, the screening of the PIC system must be leakproof.
By screening i assume you are refeering to the housing/box i will be putting
it all in?
> RSM?). One more thing: there seems to be a connector (at least in my
> Peugeot) in the engine room into which the engine analyser is connected,
> may be it has buffered outputs that could be used?
I have a connector there for two things, one is for engine RPM and the other
is something else im not sure of. I am unsure of the actual format of the
rpm signal either. another reason to get my hands on a CRO.
my car is a 1991 Nissan Silvia K, there is a connector for whats known as a
"CONSULT PORT", however, this seems to be a propriatry Nissan thing for
which i have been very unsuccessful over the two years to get my hands on
the specs or proper wiring diagrams. (last time i tried to wire something up
i blew an accessory fuse..lol. ) Cars of this age dont have ODB-II although
i think consult might be ODB-I compatible, but, i cant find proper specs on
ODB-I available (for free).
Thanks for the help people, if you come up with some other ideas please let
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