On Sun, 22 Nov 2009 21:18:20 +0000, Tim W wrote:

Steve Walker
wibbled on Sunday 22 November 2009 20:47


Yes, I'm fed up of having a string of red squares or circles across my
vision as I look from one side to the other behind an LED lit car! The red
man on newer pedestrian crossings can have the same effect.

SteveW

There's simply no excuse for it. I was messing around with AVR
microprocessors and RGB LEDs, doing PWM on each element with a fixed cycle
period and variable mark/space. No problems running in the many kHz or even
10's of kHz.

Now, if for some reason this is problematic over metres of rough car wiring
looms, then the answer (if they want to be clever) is to build the lamp
controllers fairly local to the lamp clusters and slick them on one of the
control busses. Doesn't have to be one per lamp, could be 2 or 4 for
front/back or corners, plus another set for dash and interior.

I assumed they did something like this anyway to cut down on the number of
heavy copper conductors running everywhere, but I haven't looked hard
enough at my car to inspect the wiring looms to the lights.

If that is undesireable for them, (ie they are cheap or want to be simple)
then they would be better sticking with simple bulbs (which could be LED
bulbs in the same format with the same drive).

I must admit that I thought that as more and more cars use canbus the lamp
controllers would all be local to the lamps. As you say, this reduces the
weight of copper that is needed.

As for the the frequency, indeed, there is no excuse for using such a low
rate.

SteveW