Re: MDS "on" LED...

From: Steve Preston (steveophonic@yahoo.com)
Date: Sun Feb 03 2008 - 13:42:23 EST


Viola!! You are correct,sir..yes! Heh heh heh (think
Ed McMahon here) :)
--- Jason Bleazard <dml@bleazard.net> wrote:

>
> Bernd D. Ratsch wrote:
> >
> > Just make darn
> > sure you don't ground the signal circuit - PCM
> goes "bye bye".
>
> Which is exactly why you want the resistance of an
> added circuit to be
> as HIGH as possible.
>
> It actually depends on whether you're adding things
> inline to an
> existing circuit, or creating a new circuit in
> parallel. Going inline,
> you want the resistance to be as small as possible
> so you don't affect
> the existing circuit. If you're adding a new
> circuit in parallel, you
> want the resistance to be as large as possible.
>
> It sounds like Steve is thinking of adding a new
> circuit in parallel for
> his LED. That would make more sense. If it was
> inline, then all the
> current that goes through the existing circuit would
> drive through the
> LED, which probably isn't what he wants. Who knows
> how much current
> goes through that line, it might be too much or too
> little to drive the
> LED. If he tries to change the resistance to keep
> the LED happy then it
> won't make the PCM happy.
>
> Now, if he adds a parallel circuit for the LED it's
> easier. There's
> currently no LED circuit there, and an open circuit
> (or one that doesn't
> exist) is infinite resistance. It therefore pulls
> zero current. You
> want to keep it as close to the current situation as
> possible. Keep the
> resistance as high as possible while still
> illuminating the LED, which
> will make sure it draws the bare minimum current
> that it needs.
>
> I wonder if a low-power relay would pull even less
> current than an LED.
> Steve, if you're feeling ambitious, that might be
> worth investigating.
> Hook up the relay input in parallel, then use the
> output to drive the
> LED circuit and completely avoid connecting the LED
> to the PCM.
>
> If you add a new low-resistance circuit, it adds a
> large current draw.
> Zero resistance (i.e. a "short") is what lets the
> magic smoke out of the
> parts. Remember, V=IR.
>
> --
> Jason Bleazard http://drazaelb.blogspot.com
> Burlington, Ontario
> his: '95 Dakota Sport 4x4, 3.9 V6, 5spd, Reg. Cab,
> white
> hers: '01 Dakota Sport 4x4, 4.7 V8, Auto, Quad Cab,
> black
>
>

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