Heatsinks in Europe

Nope.
I should change location in August/September, so I will wait til that's done before I make any new light.
If I'm lucky, maybe a new bin will be available by then ... but I doubt it.
 
I'm looking for heatsinks that can take the 3950 series of cobs. I'm looking at something to take 4 of them. Anyone got a good place to get them pretty cheap? I'm really not sure of the size I should be looking for. I once came across a post about the best sizes ..... lost that long ago (researching stoned didn't help).
 
Hello everyone
To be very clear and brief: what is the size i need to cool 1 cxb3590 @1.4? A square of 20x20x3cm is enough? 30x30x4, more, less?
Thanks and have a nice day★
 
...maybe help a bit...but its only my inexpert opinion...

Passive = 75 sq. cm/W or 11.62" in/w
Semi = 55 sq. cm/W or 8.52 in/w (weighted toward passive for safety)
Active = 25 sq. cm/W or 3.87" in/w

Typical Forward Voltage CXB3590

36 V @ 2400 mA (36 V version) (85°C) ....36 x 2400 / 1000 = 86,4 w
72 V @ 1200 mA (72 V version) (85°C) ....72 x 1200 / 1000 = 86.4 w

…+ or - ...87 W…

87 x 75 = 6.525 cm2 for 87 W… ...Passive...
87 x 55 = 4.785 cm2 for 87 W… ...Semi...
87 x 25 = 2,175 cm2 for 87 W… ...Active...

saludos
 
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Bonjour
@salmonetin, 75 square cm for 1 watt or 7, 5 square cm? Because 75 sq cm it is big? And 6, 5cm2 active for 87w look small but I'm going to run them at 50w.
Just tell me, if i go the passive cooling way for 50w dissipation without fan (i will had one anyway!) What is the size of the SQUARE heatsink i need to use, how many fins and how thick it must be: Exemple Take a 15x15x3cm to cool passively 50w...ho thank you that is clear answer for a noob like me!..See what i mean? Thanks!!!
 
75 square cm for 1 watt ...passive

....the numbers are only references... you must test if your size elected ... go ok with your personal conditions...

....the numbers are weighted toward passive for safety... ...but its only a reference...

....and its only my inexperts opinions.. maybe you need others experts opinions...

...i try a clear answer... but you search a better answer than mine answer...

...sorry.. im only one noob more....

pd... on the count of cm2 ...the number and size of fins counts too...

..we measure the perimeter (on perimeter count the number and size of pins too) of the heatsink in cm starting for example by base...
...after we multiply the perimeter by the length of heatsink to obtain the surface of the heatsink in cm2...

...and pardon for my short and bad english write explications...

pd2... cm2 its only one system of aproximation... other its search heatsink considerating Rth of heatsink....

https://www.rollitup.org/t/heatsinks-for-diy-led-lamps.851907/page-42#post-11595218

saludos
 
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Bonjour
I excuse your bad English. ..lol
Sorry but I m gonna spend a lot in my cxb 3590 so i want to be sure about every details!
I found 1000x165x35cm grilled alu plain 14 fins is it ok with 3 3590 cooled by 3 100mm or 120mm fans or will i need a bigger one and if the fans fry does my cobs too?
Sorry if i don't understand everything i am a noob in cob heatsink,electricity but i really want to learn to avoid any mistakes!
Have a great day★
 
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...well at least i try... time to see others answers...

...good luck LJ and have a nice day...

saludos
 
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Bonjour
Sorry but i am bad at math so i just want tp know if the heatsink (1000x165x35 14fins in inch about:40x7, 5x1, 4 ish)i "choose" is going to prevent 4 cxb3590 at 50w to fry if my fans stop, that's it!
Thanks and have a great day
 
Bonjour petit Jacob,

It's really not that complicated to (re)learn how to calculate perimeters and areas ;)

How tall are the fins/base ? Got a link ?
 
EfficientWatt said:
link is wrong in previous post, and can't edit anymore.

I mean 1371HS not 1071HS. It's 15cm for 15 fins. :bigjoint:(this is becoming embarassing) ;)
http://www.bal-group.com/heatsink_detail/200

heatsink-gif.3389286


Estimate : (3.95 * 2 + 15 * 2 + 28 * 3.05) * 2.54 = 313.182 cm² / inch
Click to expand...

example....for my pov.. the perimeter on red... not totally collored (im too bad editing pics) but its only an example...

heatsink perimeter1.JPG

...my short english its a wall for me... to explain...

...for me its...

...150 + 39,5 * 2 + XX (superior zone extrem "fins") * 2 + 30.5 * 28 + XX (inferior zones/sup zones of base) * 14 + XX (superior zones of fins) * 13 = .....cm

..after we multiply the cm of perimeter by the cm of length of heatsink to obtain the surface of the heatsink in cm2...

...for EW its....

Estimate: (3.95 * 2 + 15 * 2 + 28 * 3.05) * 2.54 = 313.182 cm² / inch

...better go with EW maths... im bad on maths...


saludos
 
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Yup,
that's the one I will go for, when I do go for it (couple of months to wait before i change location and start my build ... )

Looks so perfect to me :rolleyes:
 
salmonetin said:
...mmmm... 150 from base dont count on perimeter?...

....for my pov the perimeter on red... not totally collored (im too bad editing pics) but its only an example...

View attachment 3436774

...my short english its a wall for me... to explain...

...for my pov your count of perimeter its wrong...

saludos
Click to expand...
He's got it right, there's 2x15 for the base if you look carefully. The actual perimeter will be slightly higher as the fins are serrated.
 
....now i see my fault ....:wink: :lol::lol:... thank alesh...i edit the post...

...and thank EW for the "example"....;)
...my real math calculator to follow the perimeters ...good for people bad on maths... ;-) :fire:

images


:peace:

saludos
 
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The efficiency of a heat sink is non linear to the length.
therefore any calculation on the surface is incorrect

here we double the lenght from 50 to100 to 200mm
the red line is what you think you get out...

hs-eff.png

b.t.w. the function behind this curves is a inverse hyperbola
 
...thanks Guod...

...i know these Guod ...and yes its other great consideration when dealing with the large side... ...and the surface calculation its only one aproximation (maybe a bad one) system... ... its only one reference more... ...we not always have the Rth values for heatsinks... ... but its good know how to do the surface calculation on cm2 for an heatsink too...;-)

...the inverse hyperbola... too much for me... im bad on maths...

@guod please need your opinion... ...what multimeter/s brands/models you recomend?... on the economics range... on the midle range... on high range... sorry for my bad and short english write...

pd...Wilson... acepto esa apuesta... aunque no creo me conteste... tal vez por alguna mala accion perdi el favor de los dioses...

saludos
 
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Guod...thanks a lot ...

...La cuestion esta en ver que es lo que mas se necesita...
...el medidor que utilizo el fluke 7-300 es muy robusto y facil de usar...
luego esta el dm620, un poco lento, pero bueno para mediciones a largo plazo (es registrador de datos)
mi sueño es el mtx 3292

tu mix español- google es casi perfecto...

muchas gracias de nuevo...

...:hug:

....some news on your proyects?... i need some actualization on your thread ... i miss a second part... or maybe some other clues... ...i know i know... time.... i hear the sds voice eco... no have time...no have time...;)

...siempre hazlo cuando puedas y quieras...aprecio mucho tu punto de vista...

cuidate mucho

para ti saludos y un abrazo
 
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