Wiring Up Power Supply to 64 1 watt LED

[the kidson]

Hello all...Ive been a registered lurker for a while....my first official post...my question is as follows....I am building a 64 1 watt LED array to be used as a work light....it will operate off 12V DC....i figured i will need a power supply of about 80 watts to power all the LEDS off a 12 v DC source...correct?..now my next question is..how exactly would i wire them up to the power supply?...i am just a bit clueless on this...so any point in the right direction is much appreciated...i thank you for your time....

 

[Brevor]

Can you post the datasheet for your led's ?

 

[the kidson]

thanks for your reply Brevor...much appreciated...i couldnt find a datasheet...they are being bought off eBay...but the info posted in the sale states the leds Forward voltage is 3.2 to 3.5v at 350mA....i apologize if this is a bit vague...as always thanks..

 

[Reloadron]

Looking at the data if we figure the led Forward voltage at about 3.33 volts with a forward current of 350 mA. You could place the LEDs in series with groups of 3 for a voltage of 10 volts. That would give us Vsupply 12 volts - Vled 10 volts = 2 volts. The current is .350 amp so we get 2 volts / .350 amp = 5.71 ohms. So you want about a 6 ohm 1 watt resistor for each series group of 3 LEDs. Making 21 combinations like this would give you 63 LEDs used. The current in each of 21 branch circuits would be .350 amp so you get .350 * 21 = 7.35 amps or figure 8 amps * 12 volts = 96 watts so figure you want a 12 volt 100 watt PSU source.

That is just a rough one way to think about going about it.

Ron