[time-nuts] Hi Power LED Light power supply...

[Tom Knox]

I think that even flicker you cannot consciously see, subconsciously can have effects of mental fatigue and eye strain. This is why most florescent fixtures are in pairs firing at 180 degrees.
An optical sensor on a scope should allow the power supply to be tweaked for a steady light. 

Thomas Knox



> To: time-nuts at febo.com
> From: hmurray at megapathdsl.net
> Date: Tue, 18 Sep 2012 10:15:32 -0700
> Subject: Re: [time-nuts] Hi Power LED Light power supply...
> 
> 
> lists at rtty.us said:
> > There are a *lot* of TV's out there that refresh at 60 Hz or less. 
> 
> Many years ago, we had a busted fluorescent light at work.  I could see the 
> flicker out of the corner of my eye.  I found it annoying, so I'm a firm 
> believer that some people can see flicker in some conditions.  (Fortunately, 
> it was in a location where I didn't spend much time.)
> 
> Direct vision was not a problem.  I assumed the lamp was running at 60 Hz 
> rather than 120 and that peripheral vision was better at detecting 
> flicker/motion.
> 
> 
> Wiki has an interesting page on this stuff:
>   http://en.wikipedia.org/wiki/Flicker_fusion_threshold
> 
> the rod cells of the human eye have a faster response time than the cone 
> cells, so flicker can be sensed in peripheral vision at higher frequencies 
> than in foveal vision
> 
> But also:
> The maximum fusion frequency for rod-mediated vision reaches a plateau at 
> about 15 Hz, whereas cones reach a plateau, observable only at very high 
> illumination intensities, of about 60 Hz
> (I think that is backwards from the previous line.  I'd guess somebody typoed 
> rods-cones.)
> 
> Note that LEDs without diffusion are high-illumination, so I'm not surprised 
> if some people report flicker troubles.  It would be interesting to 
> investigate some examples.  I wonder if they are 120 Hz or 60 Hz?
> 
> 
> More wiki:
> 
> For the purposes of presenting moving images, the human flicker fusion 
> threshold is usually taken as 16 hertz (Hz). In actual practice, movies are 
> recorded at 24 frames per second, and TV cameras operate at 25 or 30 frames 
> per second, depending on the TV system used.
> 
> Even though motion may seem to be continuous at 25 or 30 frame/s, the 
> brightness may still seem to flicker objectionably. By showing each frame 
> twice in cinema projection (48 Hz), and using interlace in television (50 or 
> 60 Hz), a reasonable margin of error for unusual viewing conditions is 
> achieved in minimising subjective flicker effects.
> 
>  
>   
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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