Europe - where to buy cxb3590 or 1212 Cob KIT KIT KIT Plug and play

KonopCh said:

You didn't answer me.
I know about better coverage and penetration with strips. I was asking around but didn't find single row strips, that's why I am looking into cheaper Citizen 1212, which are 8€ per piece and 170 lm/w at 700 mA - same as strips. At Digikey and Arrow I must pay importing taxes, VAT and shipping so Citizens are way cheaper for me. I was thinking about 12-15 Citizens at ALU plate or U channels.

Click to expand...

I've already answered such a plate is enough for up to 480w. 12 Citi1212 @700mA would be ~280-290w. Multiply that by 55cm²/w and you need a heatsink with ~16.500cm². A plate with 900x 900mm would be sufficient for ~300w(16.200cm²). With added channels on the backside you need probably only 800x 800mm.

I've glued a small U-channel into a bigger ones to increase the surface area. Looks like this:


It's a 40x 30x 2mm and a 20x 25x 2mm profile and a 1150mm long piece is enough to keep 70w Bridgelux V18c COB's below 50°C. I measure stabilized 43°C on the backside of the heatsink with ~28-29°C ambient..
Hope that answers your question.

BTW,
when you use the 110cm²/heatwatt formula you can calculate surface area more precise because you can calculate COB effiency in. A CITI1212 @700mA is probably >55%, and if you calculate with 55cm²/w you calculate always with 50%.

PS.
From @diyled you could get strips without VAT/customs

@Randomblame I don't understand your math. 90 x 90 cm = 8100 cm2 ... why are you multiplying with 2 cm instead of 0.2 cm ? 2 mm is 0.2 cm.

X 2 not x 2cm! Because we calculate surface area and a sheet has 2 sides for heat convection. With 90 x 90 x 0,2cm you calculate volume in cm³.