On 24/05/2017 22:15, Graham. wrote:
On Wed, 24 May 2017 20:57:28 +0100, Andy Burns
wrote:

Michael Chare wrote:

is it really the
case that a rear light unit with LEDs and driven by CAN bus, with two
thin wires for the power and two even thinner wires for CAN-H and CAN-L
bus is really cheaper to make than one with convention bulbs and much
thicker wires?

Well yes, because thick copper is expensive, and those 4 wires (and
multiple CAN chips) can individually drive
tail/brake/indicator/reverse/fog lamps ...

The other thing is that the solid state LEDs essentially last pretty
much forever so you can dispense with sockets in many cases.

There is a slight problem with some of them producing a too collimated
beam of light so that they dim as you get closer but further off axis.
This is actually a benefit for motorway signs at night since it makes
them visible from further away without dazzling close up. But in bright
sunlight on cars it can work against being able to see them close up.

Also the chips start to do snazzy things such as dimming one side's
front running lamps when indicating or providing the "moving pulse" on
newer indicators

How about a different cadence for hazard lights, so you don't mistake
them as an intention to pull out when the nearside indicator is
obscured.

That is actually a damn good idea now that the flashing is no longer
determined by the vaguaries of a bimetallic strip and heater or simple
astable. dot-dash-dot-dash would be the most unambiguous.

--
Regards,
Martin Brown