DIYbanter - View Single Post - Why aren't many / most LED light bulbs dimmable?

Don Klipstein

In , zzzzz wrote:
On 12/27/2010 16:54:10 +0 UTC, (Don Klipstein) wrote:

In , zzz wrote:
On Sun, 26 Dec 2010 23:56:01 +0000 (UTC), (Don
Klipstein) wrote:

SNIP to here as part of editing for space that I did here

I've tried all sorts of things for seeing around with little light.
My experience says to make use of night vision. A cool white LED can
illuminate a room to extent that I can walk around and see everything,
using a couple to a few percent as much light as if I used red light.

That's interesting and a bit counterintuitive. I can see fine around the
bedroom, at night, with only the backlight of my XM radio but it's quite
bright. I guess it's not enough to trigger the iris but still make use
of the higher sensitivity wavelengths. OTOH, for astronomical viewing
(and submarines one uses red lights.

Oh yes, I do remember my stretch of time when I was into astronomy.

Red lights were used to see things other than stars, such as star maps,
so as to see in high resolution (from photopic vision) with light that
does not overload and reduce sensitivity of scotopic vision.

I would think the requirements of nightlights are usually different. I
don't see the need to be able to read a newspaper - only to recognize it,
to be able to read the name of the newspaper. There is also the fact
that I don't mind having my night vision attenuated a bit by using a light
that makes use of it for this purpose. I have some green and blue LEDs
that can illuminate a largish living room that well to me with maybe .1
milliamp (and full dark adaptation), though I would only count on low
current performance good enough to do that with .25 milliamp.

I still don't want to lose "night sight" when I stumble from one room
into the next, at night. The light doesn't alter my Braille ability,
though. ;-)

I'm thinking that illuminating a largish living room with one of my
favorite green or blue LEDs at .1-.25 mA will be low enough on blasting my
night vision for me to still have a majority of it, probably around/over
75% of it.

Then again, I can illuminate all rooms and the basement of a McMansion
that brightly with 50 milliwatts for the whole house.

(Not that I get a good ROI for doing so, in comparison to getting
commercially available LED nightlights using ~100 times as much power
and producing a few times more light.)
--
- Don Klipstein )