Hi. I'm trying to figure out the whys of this board. It holds 12 high power led's in series. When I soldered the led's to the board and apply 18vdc, only 6 led's light up. The red traces are the power path (confirmed by meter). All of the led's work individually. Any ideas?
PS I bought these from China and there is no other data available. (at least not in English)
Thanks for any words of wisdom.

 

Can you find the current?

 

You need a constant current power supply and you need a voltage higher than the sum of the forward voltages of all the leds in series..

 

You need a constant current power supply and you need a voltage higher than the sum of the forward voltages of all the leds in series..

Thanks, i thought that none of the leds would light if the v was too low. I put 4-9v batteries in series, BINGO.
Thanx for your help

 

Thanks, i thought that none of the leds would light if the v was too low. I put 4-9v batteries in series, BINGO.
Thanx for your help

And what are you using to limit the current to the LEDs?