Lighting Help with 1212 build

[2Stoned2Care]

Would something like this work?

https://www.ebay.co.uk/itm/252559707114

Plan would be get one 2 foot long and then split it into 4 sections and mount a cob in the middle of each section, I'm guessing it's too thin, but if I could get a solid block it be great, mount cobs to it and just hang the whole block

This is what i got bro.i bought a 40cm length and put 4 1212's on it with a 120mm fan on top and the heat sink never goes above 72
http://www.ebay.co.uk/itm/Aluminum-...hash=item1ea01e42d1:m:mUmeObwN4TYRKRW3C5qYtlQ

 

[Whiskytoad]

This is what i got bro.i bought a 40cm length and put 4 1212's on it with a 120mm fan on top and the heat sink never goes above 72
http://www.ebay.co.uk/itm/Aluminum-...hash=item1ea01e42d1:m:mUmeObwN4TYRKRW3C5qYtlQ

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What length is that one? In thinking a 2 foot long one won't need a cooling fan which Is the route I want to go!

 

[2Stoned2Care]

What length is that one? In thinking a 2 foot long one won't need a cooling fan which Is the route I want to go!

That one is 40cm/15 inch long bro.i was thinking of getting a 80cm one to spread the cobs out more so a 2ft would be great

 

[Whiskytoad]

That one is 40cm/15 inch long bro.i was thinking of getting a 80cm one to spread the cobs out more so a 2ft would be great

I'm gonna order a 600mm one tonight, hopefully someone more expierenced than me can confirm it would work fine passive for 200w of cobs, can't be bothered with having to buy more cobs haha

 

[Whiskytoad]

Ok is there anyone that can check my math?

I'm gonna be running 4 1212s with hlg 185h 1400b I bought one of these heatsinks in 600mm
https://www.ebay.co.uk/itm/131535356625

Now I've got max case temp on the 1212 being 105, I rounded this down to 85 for safety and it makes the math easier I assume the cobs will be 30w heat, again making this higher for safety and math, ambient temp being 25ish so that gives me (85-25)/30 for one which is 2c/w, a 150mm is well below that running passive at 1.25c/w, I am unsure how this work for running it all on one block though? I can easy cut heatsinks into 4 of need be.

Or do I need to start buying some pc fans?

@BigSm0 since you seem to be the friendliest expert here

 

[2Stoned2Care]

Ok is there anyone that can check my math?

I'm gonna be running 4 1212s with hlg 185h 1400b I bought one of these heatsinks in 600mm
https://www.ebay.co.uk/itm/131535356625

Now I've got max case temp on the 1212 being 105, I rounded this down to 85 for safety and it makes the math easier I assume the cobs will be 30w heat, again making this higher for safety and math, ambient temp being 25ish so that gives me (85-25)/30 for one which is 2c/w, a 150mm is well below that running passive at 1.25c/w, I am unsure how this work for running it all on one block though? I can easy cut heatsinks into 4 of need be.

Or do I need to start buying some pc fans?

@BigSm0 since you seem to be the friendliest expert here

I would just put them all on the 600mm heat sink bro with 1 120mm fan in the middle,mine does not go over ambient temp in my tent

 

[2Stoned2Care]

I remember when i put mine on without the fan that i could not even touch the heat sink it was that hot,thats why the round pinfin heat sinks are so big to dissipate the heat more

 

[BigSm0]

There is more light from cobs than leds and hps so there is more thermal radiation which is part of the heat you get from light. The more efficient the more thermal radiation and the less conductive heat which is the part that gets the heatsink warm. Either way I'd assume full wattage when sizing the heatsinks and not the efficiency calculation. I'd say that sink is to small for the cobs without some sort of fans. Even though I like math I prefer to use my best judgement. An example is my side light bar that's 120cob watts on nothing but 1/8" aluminum stock measuring 3" wide. I spaced the 6 cobs out 16" on center. The math said it wouldn't work but with air movement in my room the highest temp behind the cobs was 90 degrees. For this build I'd add 2 pc fans to the top, a small apv meanwell and cover the backside fins to keep air between the channels and you'll have one super cool light.

 

[Whiskytoad]

There is more light from cobs than leds and hps so there is more thermal radiation which is part of the heat you get from light. The more efficient the more thermal radiation and the less conductive heat which is the part that gets the heatsink warm. Either way I'd assume full wattage when sizing the heatsinks and not the efficiency calculation. I'd say that sink is to small for the cobs without some sort of fans. Even though I like math I prefer to use my best judgement. An example is my side light bar that's 120cob watts on nothing but 1/8" aluminum stock measuring 3" wide. I spaced the 6 cobs out 16" on center. The math said it wouldn't work but with air movement in my room the highest temp behind the cobs was 90 degrees. For this build I'd add 2 pc fans to the top, a small apv meanwell and cover the backside fins to keep air between the channels and you'll have one super cool light.

Ahh was hoping you wouldn't say that..! But since you have, how easy would it be to add a couple UV LEDs in to the fan wiring just to make an extra kickass light

 

[dankle]

Ok ok looked at the artic sinks, will this work? https://www.scan.co.uk/products/arc...1151-1155-1156-up-to-47w-tdp-silent-aluminium

Chips are only running 50w so surely 47w of cooling is enough? Or am I an idiot?

A 50W cob or 048-1212 at 50% efficiency will disperse 50% heat and 50% light+heat. Running on a HLG-150H-48A all the up, at about 60W, the heatsink does get pretty hot, except with a fan near. 50W gets pretty warm with no air movement but the heatsink can definitely handle a 1212 at 50W.

I started out with cobs building active cooled systems but Im finding I can acheive better results running passive cobs softer. Im considering 36W or 25W with this heatsink for the next build.