led pcb mystery

Thread Starter

Heikki

Joined Sep 7, 2014
3
Pcb has 2 x 21 strings in series
leds are 3w and of 7 different kind
is it even possible to make such strings
with out burning the house down
 

mcgyvr

Joined Oct 15, 2009
5,394
Sure you just need a driver with an output voltage higher than the series strings forward voltage rating.

For safety many drivers only go to 48-52V (60V SELV) max DC output.. There are some that go higher.


Hope you realize too that ALL the leds in each string will get the same current so you can't mix 300mA and 750mA (well if you do you should only drive them at 300mA) .. They will all be driven at the same current level.
 

GopherT

Joined Nov 23, 2012
8,009
Assuming most white LEDs are 3.3 volt forward voltage, each string will have a 70 volt drop and 126 watts (3x42) on a 150x200 mm plate? Fire? It is possible.

Note that fire is possible from poorly designed electronics and circuitboard but, instead, from radient energy. LED flashlights of 30 watts and more can heat place paper or electrical tape to combustion (depending on focal length and distance).
 

Thread Starter

Heikki

Joined Sep 7, 2014
3
Hmm i guess i ll skip the white ones then and figure out a combination of the rest for a 21 string..

i have 2x 300x120x20 heatsinks i intend to use and 4 x 100mm fans for each 2xheatsink
20140907_204059.jpg
20140907_204059.jpg


I was hoping it would be possible to connect 2 x pcb on the heatsinks and then controll it all via arduino,

20140907_204128.jpg
20140907_204128.jpg


Thanks for all input and critic , now its back to the drawing board and back here for a revisit ,

tip of the hat..
 
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