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Omnidirectional LED lightbulb is OK?

eem2am

Aug 3, 2009
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Hello,
The below (attached) is an omnidirectional LED lightbulb. It comprises seven PCBs, each one "aiming" in a different direction so that the light is spread out evenly, just like in one of the old incandescent bulbs.
Do you think that this solves the problem of the individual LEDs narrow beam-ness?
Surely a 15W version of this would be brighter than an old 100W incandescent bulb?

The LED PCBs would all be big enough, and comprise enough cooling copper "land" area , such that no aluminium heatsink was required. Making aluminium from bauxite takes prodigious amounts of energy, so aluminium should not be used in heatsinks for lightbulbs....do you agree?
 

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duke37

Jan 9, 2011
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This looks like a reasonable solution.

The area of heat sink will not vary much with the heat sink material if the conductivity is adaquate. For the same conductance, I believe that aluminium is lighter than copper, also, if the copper is insulated on one side it will be inhibited.

Aluminium is much more common than copper so should be preferred. To reduce the use of aluminium, then ban drink cans.

Rather than replacing complete faulty components, repair instructions and parts should be available.
 

eem2am

Aug 3, 2009
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getting aluminium from bauxite takes prodigious amounts of energy..
http://en.wikipedia.org/wiki/Aluminium_smelting

...Aluminium drinks cans are a mistake, and yes, they should be done away with, or at least, only made from smelted down aluminium, and no new bauxite "converted" to make their aluminium.
Aluminium drinks cans only use very thin aluminium, so it is a minimal form of aluminium use.

The thing about aluminium drinks cans is that they are very thin aluminium, and they are thus easier to smelt back down with lower energy usage, wheras aluminium heatsinks are more chunky and require a lot more energy to smelt them back down.
 
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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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The thing about aluminium drinks cans is that they are very thin aluminium, and they are thus easier to smelt back down with lower energy usage, wheras aluminium heatsinks are more chunky and require a lot more energy to smelt them back down.

This is true the same way that 1 tonne of lead is heavier than 1 tonne of feathers.
 

eem2am

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no seriously, smelting coke cans back down to molten alu takes less energy than smelting down chunky blocks of alu of the same weight.
 

duke37

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no seriously, smelting coke cans back down to molten alu takes less energy than smelting down chunky blocks of alu of the same weight.

I think this is rubbish. The energy needed to recast the aluminium will be dependant on the mass as Steve says.

Also, the aluminium will oxidise during the melting so a portion will be lost, the oxidised aluminium has to be skimmed of the suface of the melt. The amount of oxidation will depend on the surface area which will be much higher in a drinks can than in a chunky heat sink.

A heat sink should last for decades, a drinks can perhaps a few days so needs to be remelted many times.
 

eem2am

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A heat sink should last for decades
yes it should , but when a led lightbulb with an alu heatsink fails, that heatsink will be the wrong size and shape to be fitted in another led lightbulb, so it will unfortunately need smelting back down.
This is not an acceptable use of energy....and can be avoided by not using aluminium heatsinks, but instead using large led pcbs with enough cooling copper to cool the multiple low-power leds.
These led pcbs, when they fail, they can just have the leds desoldered and then fresh leds soldered back on again.
vvv
Is there anything intrinsically wrong with this thread?.....I posted a similar thread on a different forum, and very politely explained the whole purpose, and yet it was hotly rebuked, and after 49 threads, that forum deleted all 49 threads.

The purpose of this product is to do domestic mains lighting with repairable LED lightbulbs...so that no glass gets thrown away like it does with CFLs (since not all of them get returned to the CFL collection points).
We also want to avoid aluminium heatsinks, as these just end up getting smelted back down when the bulb dies...this is a waste of energy.
vvv
One other reason to use many small leds (& no alu heatsink), instead of a few bigger power leds (but with an alu heatsink), is that bigger power leds comprise a central thermal pad which would be difficult to hand solder when the LED PCB is being repaired after its lifetime use. (you can see the thermal pad on page 14 of the golden dragon datasheet)....

Osram golden dragon 3W power led:
http://catalog.osram-os.com/catalog...=downloadFile&favOid=0200000200039541000200b6


...you see, in the other forum where this whole idea was rebuked, they seemed to think that it would be best to simply use an alu heatsink, of a standard size, and literally re-use that heatsink. -That all sounds very well, however, firstly, how are we going to make multiple private companies come together and agree on one (or a few) standardised heatsink shapes? Also, as just mentioned, if an alu heatsink is used, then we'll obviously be using a few small, higher power leds, (since the heatsink is there), and thus the problem with desoldering and re-soldering leds to the PCB when the LED PCB eventually fails and needs repair (due to the difficulty of hand soldering the thermal pad)

Anyway, this whole idea of repairable domestic mains lightbulbs was quite viciously rebuked in a different forum....there were 49 posts in the thread, where the idea was passed off as almost lunacy, then they deleted the entire thread, and banned me from the forum. Is this idea that bad?

In that (now extinct) thread, I mentioned that the repairable bulb was LED based, and at least LED bulbs don't contain mercury, but this was rebuked, and their forum members told me that 20 cans of tuna contains as much mercury as one CFL.....so , they said, "just don't *eat* CFLs or tuna". I knew that the mercury_in_CFLs problem was not that bad, but I didn't know it was that insignificant?
 
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