Messages - Sarkand [ switch to compact view ]

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I don't know if it will be of any consolation, but:  all three of my installations are base-down.  (I use the desk lamp on my nightstand, but rarely read in bed, so it's almost always pointed upward for indirect lighting.)  In this position, the socket fixtures themselves remain at or near room temperature, so the fins clearly do a pretty good job, and I personally would not hesitate to strech 60 to 100 in this configuration.  Base-up?  Perhaps in a ceiling fan that you run all the time when the light is on, forced convection would cool to a reasonable level.  But my fingers tell me that in any shaded base-up installation, it would just have to get damned near as hot as an incandescent, even with otherwise unrestriced airflow.

The heat fins do get very hot.. Though that doesn't definitively tell us about heat comparisons.

My limited and shallow understanding of physics does tell me that since the LED bulbs are running so much more efficiently and using so much less energy -- that overall heat output must be significantly less, regardless of whether the fins burn your hand or not :)

But I could be wrong and I'd love to hear more from people who know.  If I am wrong, then i have just poured a bunch of money down the drain for little good reason.

I don't remember much of my high-school physics either, and I was mercifully spared in college.  So I may be talking nonsense.  But if I remember what little I do correctly, the total amount of heat generated by any electronic device is a function of its resistance, not the interplay of voltage, wattage and amperage.  The efficiency of the bulb is due to reduction of wattage (don't know about the amperage, input voltage is obviously the same).  But considerable heat can be generated at very low power, if resistance is high enough.  Even a small flashlight bulb gets pretty hot when illuminated for a few minutes.  Indeed, it's the heat produced by resistance that generates the incandescence.  LEDs are more efficient because they use less total power throughput relative to incandescents to produce a roughly equivalent number of photons.  This all seems pretty obvious.  What is not obvious to me is why so much heat is still produced.  Is the LED driver the equivalent of a step-down transformer?  I think that would account for it.

I understand your desire to reduce heat - I have a similar problem in my place in the summer.  I, too, thought they would run much cooler and was surprised to feel the high heat of the fins.  But I wouldn't lament too much if you don't get the reduction you expected - if the bulbs perform as advertised, they will pay for themselves many times over.  And surely someone has made this heat comparison somewhere.  Have to see if I can dig it out.

...However, I am motivated by the decrease in heat output -- in the summer my incandescents can generate a large amount of heat and i'm very keen to reduce that.

I have installed three Kobi (made in China) LED 75W equiv., 5000K, in my room.  One in a floor lamp, one in a table lamp and one in a reading/desk lamp.  I have been very satisfied so far.  I like the bright light - all three are essentially positioned for indirect lighting - but the desk lamp I have used for reading, and it's great.

I have noticed, however, that while the bulb itself stays quite cool (body temp?), the radiating fins at the base become quite hot.  I am not able to touch them for longer than about .5 sec. at a time.  Perhaps this is because of the "made in China" stigma deprecated above, but they have been working very well for several months with no problems.  If what I have experienced is common, you really haven't done a whole lot to reduce total heat output.  I'd like to know if others have detected this high heat of the radiating fins between the base and the bulb itself.

Finished Programs / Re: SOLVED: "Dressed" links
« on: January 05, 2014, 05:08 PM »
No objection at all.  It is certainly solved for me, thanks again to Iain.   :D  :up:

Finished Programs / Re: SOLVED: "Dressed" links
« on: January 01, 2014, 05:26 PM »

   No worries, sorry you're feeling so bad, been a bit under the weather myself, and know what sleep deprivation can do to you.  I have tons of extensions in FFx as well.  I've been using ColT for so long that I forgot where this context menu came from.  I have very little idea what rich text format is about, since I've done very little, and very simple, web programming.  In any case, this is exactly  what I wanted to do, and I thank you again for having the answer.

Cheers, and have a Happy New Year

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