Re: SI reset tool information - here's the goods.

[John Firestone <john.firestone@xxxxxxxxxxxxxxxxxx>]

bohnen@domain.elided (Aaron Bohnen) writes:
>
> 2. a directional jumper lead with both a diode and a resistor. I'd suggest 
> a reasonably hefty diode, not because of the admittedly low voltages and 
> currents, but rather because of the durability issues involved. A suitably 
> rated diode is very small and very flimsy in physical construction. In my 
> opinion, more durability is desirable. 
> 
> My personal version of this tool uses a 600+ Volt [3] Amp high speed
> fast recovery Motorola part . . . [and] a resistor in series with this
> diode. I suggest a 470 Ohm resistor which will limit the potential
> current flow from the reset pin to any other pin of under 11 mA in
> case of a misconnection of the tool.

While a desire for more durability is laudable when designing other
things - bridges, for example :) - in this instance, a 600V 3A diode
is probably overkill.  Much of the car's electronics is already diode
protected to at least 10 ma.  In 12v circuits, a 470 ohm resistor might
allow too much current.

If you were to omit the diode and use a 1.5K resistor, your
circuit would be simpler and might protect just as well against
misconnections.  You might consider a higher resistance value in light
of some of the ISO/TC 22 standards, but I would not bother, since you can
only use the tool when the car is quiescent, electrically speaking.
But perhaps an EE will comment.  My PhD is in geophysics.

> Good luck and keep your eye out for more news on the mating connector...

Are you looking for one or are you asking us to help out?   I 
can suggest something for an E36.  

- -John
'96 318is
john.firestone@domain.elided

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