Robert Ammerman wrote:
> My eyes are assuredly not the best, but I once built a three phase dimming 
> control system (don't ask) which broke each 1/2 into 768 steps (3*256). This 
> seemed to be enough resolution to avoid discernable step-by-step changes in 
> light intensity across the entire range, including the low end.
>   
I have seen incandescent dimmer systems work well down to 100 steps - 
some of the early digital dimming consoles worked like this. It's the 
LEDs that create the challenges at the low levels because they have no 
"fade" to smear the steps.

Alden
> Bob Ammerman
> RAm Systems
>
>
> ----- Original Message ----- 
> From: "Gerhard Fiedler" <lists@connectionbrazil.com>
> To: <piclist@mit.edu>
> Sent: Tuesday, November 28, 2006 6:59 AM
> Subject: Re: [EE] LED color mixing: RGB...O?
>
>
>   
>> Alden Hart wrote:
>>
>>     
>>> It's also worth noting that they tend to use 16 bit controls on the PWM
>>> for dimming. It seems that fewer bits than this (i.e. less temporal
>>> resolution in the pulses) gives you visible steps (quantization errors)
>>> at low light levels.
>>>       
>> If you had a log scaled PWM generator, fewer bits would be fine -- most 
>> are
>> not, but it's not impossible, depending on the technology used.
>>
>> Gerhard
>>
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