RE: LED lighting

["David Yeend" <david.yeend@xxxxxxx>]

Dave,

I have been thinking about this as well but along the lines of the
functionality of the iCove tubes previously discussed on here.

I was thinking of running 3 PWMs, each one connected to a different colour,
to create a mix of RGB with perhaps a 4th PWM to vary the overall duty
cycle and provide the brightness control - I have not tested yet but that
was the theory.

One thing I have had problems with in the past is the response time of
LEDs. I found that an LED with slow response would not allow dimming
without noticable flicker. Hit the LED with too fast a signal and it simply
illuminated a an uncontrollable dim level.

I know that with PWM we are not talking about altering the drive current
but I have seen white and blue LEDs generate different coulors under low
drive current conditions. I was wondering if trying to drive an LED with
too fast a signal may also cause similar results?

I know you use Atmel parts - the Mega128 has 6ch PWM so it could be
possible.

The Qprox idea is a nice touch, would you also implelemt 485/232/CAN or
something for remote control and status feedback etc?

You could also consider the same controller as being able to offer a
battery powered emergency / power cut lighting facility - embed a few LEDs
in the ceilings and turn them on when to power dies?

I wish I had the time.......

Regards,

David



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