Steve Preston <steveophonic@yahoo.com> wrote:
> The diode side of an opto has basically the same
> properties as an LED (it actually is an LED inside a
> sealed case),so there really wouldn't be anything
> gained by using extra parts. There's no real need for
> isolation from the circuit. The only concern is
> loading down the circuit,which is unlikely to happen.
That's true, now that you mention it, though it might still be of
some value in regards to protecting the PCM. If you put the
optoisolator as close to the PCM as possible, anything on the LED side
which manages to short to ground will at least not be seen by the PCM.
IIRC, Bernd said that shorting that line to ground was likely to
damage something. True, it doesn't help on the power draw side, but
might be relatively cheap insurance to keep the PCM safe - who knows
what will happen to the wires and the LED in the coming years? Might
have a kid/rodent/car thief (I guess the last two are the same,
sorry...) ;-) rummaging around under there at some point or who knows
what.
Then again, my electronic circuit experience is solidly in the
amateur/hobby/sketchy area so take that for whatever its worth, which
is probably not much. :-)
Oh, something else that comes to mind is it might be worth taking a
look at the MDS system in more detail - I have no idea how it works, I
know earlier systems used solenoids and such, and now that I think of
it, Bernd did mention a solenoid in this case. If they are using a
solenoid for some reason, that might be a decent place to tap power
for an LED. The power line for a solenoid, or the relay which
controls the solenoid is probably going to be a heck of a lot less
picky about changes than a PCM control circuit would be, and probably
more forgiving in the event of a mishap as well. Just a thought,
again, take it for what its worth. :-)
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
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