The LED emitters in my outdoor lamps blew out and I need to replace them but I have to rebuild the emitter from scratch because replacement parts are not available. The whole lamp was made in China. They are fed by AC.
I have the following: - 1 Luxeon K High Power LED Array. Forward voltage requirement of 20V with 730 lumens at 350mA. Perfect sized emitter and I have a good heat sink to mount it to. The Part number is LUXEON-K-COBWW08, an 8 emitter array.
1 AC to DC power converter. It is a MagTech AC Dimmable - 18-Watt, 700mA Constant Current LED Driver. I don't need it to be dimmable at the switch, but I don't mind adding a dimmer to the inner workings of the lamp. The Part number is M18-U24-0700
I can buy any resistor needed. That's not the issue.
Curiously, the DC output from the AC converters I measured to be 30V. Both of them. They are rated to be dimmable between 14-24 VDC. This is at a constant 700mA.
When I bought the drivers, I planned a 24V power to a 20V requirement and got planned for a resistor of 12 ohms. (24-20)/.35mA = 11.4 ohms. The lights are rated at 350mA. Any more current and they'll burn up.
Since the output is 30V, should I swap the 12 ohm resistor for a 30-35 ohm resistor? (30-20)/.35=28.5ohms
Is there a simple way of hardwiring a variable drop in voltage? I can set the output with my multimeter and leave it in the housing of the light.
I'm worried that, within this outdoor light, wiring a 35 ohm resistor will require me to radiate off too much heat. I'll need a 20 watt resistor.
This is getting out of my league and I think ledsupply.com sold me incorrect equipment.