----- Original Message ----- 
From: "Jinx" <joecolquitt@clear.net.nz>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Monday, November 28, 2005 11:09 AM
Subject: Re: [EE] means of dimming auto tail light?


> > of around 28 Ohms and a "cold" filament resistance of < 2 Ohms.
> > One solution of the car industry is to switch between around 3V
> > and 12V, then the difference will not kill the driving mosfet and
> > the intensity of the 3V "preheating" is nearly not visible
>
> Ah, I knew pre-heating is used in displays but was not aware of
> it in vehicles. This would be for a very short time before the 12V
> is applied - 3V not there all the time ?
>
As far as I know from some european upper class models, where no Xenon
lights or LEDs are used (f.i. last S-class models) but the lights are driven
with CAN-bus the electronic "preheats" the bulbs with around 3V. If it is
from start on or only a quasi soft-start is a fact I don't know (I read this
in a german car magazine a few years ago).

Kind regards

Enrico

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