Heatsinks for DIY LED lamps

Doer

Doer

Well-Known Member
Also, I expect to be running each COB at 2/3 max. So, I don't think I can expect near ambient, or maybe that is what the tunnel is for.
 
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FESTER665

Well-Known Member
I'll be honest, some of this is like reading in a foreign language for me... LOL

I have a 24" x 8.46 heat sink, would that be enough heat sink to do (24) 3w LEDs around the edges (red or blue depending on time) and a row of either (3) CXB3590's or (4) CXB3070's in the center of it?

I have the 3590's on order and will be running them on a HLG-120H-C700B driver, but if they're going to be delayed I'm thinking about ordering the 3070's and tossing them on a HLG-185-C1400B driver. Then when the 3590's finally arrive putting them on another heatsink instead....
 
SupraSPL

SupraSPL

Well-Known Member
I come up 9556cm², good for 135W passive cooling or 382W active cooling. That heatsink has a thick base so it is good for the unbalanced heat load of COBs. My only concern would be if you ran it active cooled and packed the wattage on there, you would not get enough spread.

In other words a heatsink that shape should be good to cover about 12" X 36" with bare emitters. You could increase spread if you used COBs w lenses and lifted it higher above the canopy, but it would not be as effective as spreading the COBs evenly above the canopy.
 
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FESTER665

Well-Known Member
SupraSPL said:
I come up 9556cm², good for 135W passive cooling or 382W active cooling. That heatsink has a thick base so it is good for the unbalanced heat load of COBs. My only concern would be if you ran it active cooled and packed the wattage on there, you would not get enough spread.

In other words a heatsink that shape should be good to cover about 12" X 36" with bare emitters. You could increase spread if you used COBs w lenses and lifted it higher above the canopy, but it would not be as effective as spreading the COBs evenly above the canopy.
Click to expand...
I'm thinking this might be another good reason to get 3070's now and then add the 3590's in certain places with smaller heat sinks after they arrive to fill in any gaps..

Thanks for all the help Supra!
 
medicinehuman

medicinehuman

Well-Known Member
what is a good 3590 heat sinks for passive cooling @1050mA and 700Ma and 1400mA. I'm a little confused right now (THAT IS NOTHING NEW) .:-?
 
Doer

Doer

Well-Known Member
You need to work some calculations and check the heat sinks here.

http://heatsinkusa.com

When you absorb this, come back with a profile that you think might fit, and we will help you understand that one and if it is good. That way you learn. OK?

:)
 
Scotch089

Scotch089

Well-Known Member
Passive cooling you want 75cm2 at 700ma your looking at 50w each.

So 50x75 for a single cob is 3750 (anyone know that song from the acacia strain? Old school..) go to the first page and divide that out by the cm2 surface area of the heatsinks and that'll give you length you need in centimeters.
 
Doer

Doer

Well-Known Member
You need to calculate the area of the sink exposed surfaces not just the square inches of the total sink.

All the sinks have different fins in 4 different ways. So, you need the perimeter value of one profile x the inches.
 
Doer

Doer

Well-Known Member
medicinehuman said:
Not sure about perimeter. Your talking to a retired roofer who is lucky to absorb anything. I know a perimeter is on a roof, all the outside edges.
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:) I've done roofing, for myself. Detailed work. And it is confusing about special meaning to words. I forget the relevant date is over in a chart listed in an FAQ.

The 4.9 inch profile says it has a perimeter of 35.270 inches, but they mean square inches. :) OK, hold that thought.
http://www.heatsinkusa.com/content/AvailableProfiles2015.pdf

For passive the thumb rule is 110w/cm^2 and 25, btw, for active.
 
Doer

Doer

Well-Known Member
So, now we do some math.

what is a good 3590 heat sinks for passive cooling @1050mA and 700Ma and 1400mA. I'm a little confused right now (THAT IS NOTHING NEW) .:-?

But, that depends on the vF variant of the 3590s.

Let's use 72vF.

50w at 700ma
75w at 1050ma
100w at 1.4ma

Most will choose 50w but not me. It is 150w COB. So I run at 2/3 not 1/3 but I will pay more for power, but have less up front cost.

So, what do you pick?
 
alesh

alesh

Well-Known Member
Doer said:
:) I've done roofing, for myself. Detailed work. And it is confusing about special meaning to words. I forget the relevant date is over in a chart listed in an FAQ.

The 4.9 inch profile says it has a perimeter of 35.270 inches, but they mean square inches. :) OK, hold that thought.
http://www.heatsinkusa.com/content/AvailableProfiles2015.pdf

For passive the thumb rule is 110w/cm^2 and 25, btw, for active.
Click to expand...
No, they mean inches. It's perimeter. Not area. Once you multiply it by length, you get inch*inch, or square inch, Mr. degree in physics.
 
Doer

Doer

Well-Known Member
But, you can only buy 1 inch min. Mr Asshole. And I was relating it to the special use of the word, as perimeter for this guy, not you. And perimeter is not a measured of area, except in heat sinks.

You are really are a clumsy, little Ego snot, aren't you?
 
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