[Brinworld] Car's data recorder convicts driver

[Riad S. Wahby]

Mike Rosing <eresrch at eskimo.com> wrote:
> Automotive environments are known to be harsh, so electronics is protected
> to some extent.  The assumption is that spark plug voltages can get into
> sensors, so most data lines are protected as are the sensor lines.  If you
> try to fry things with double the voltage of a standard spark plug it may
> not work, if you use 10 times that it will, but the ESD protection will
> obviously be blown too.  That begins to look suspicious (but I doubt
> anyone could _prove_ you fried it on purpose).

In automotive power systems, the bigger concern is load dump.  When
there's a step change in alternator load from high to low, the commutating
inductances resulting from the field windings of the alternator can't
react quickly enough, and you tend to get big spikes on the power lines.

Perhaps this could be used to advantage---if you want to convince
someone that your electronics blew up on their own, blow up the
rectifier at the output of your alternator, too.

-- 
Riad Wahby
rsw at jfet.org
MIT VI-2 M.Eng