First time poster, long time solder-eater.
I'm trying to piece together a lighting system for growing plants in sterile tissue culture; LED illumination is ideal, as we don't need the intensity used in other settings (for growing mature plants, for example).
I've decided on going with Osram Golden Dragon Plus LEDs, using two different models- one peaking in the red, one peaking in the blue. Reds run 2.15 volts, and I'm going to run them in a series of 9; at 700 mA each, that works out to about 14 watts (according to the calculator at http://led.linear1.org/led.wiz).
The other string is blue; they run 3.2 volts, and I want 1/3 as many as reds; so, with 3 blue LEDs, running at 400 mA, consumption is 4 watts. The problem is, they're at a separate voltage (10 volts).
Last night, I thought I had a solution using the website above using 20 volts for both, but Firefox crashed and I lost everything. I can't figure out how to run both strings off of 20 volts without huge resistors- and lots of wasted power.
My questions:
1) Is there any sort of way to figure out how to optimize efficiency without plugging in these numbers manually- maybe a spreadsheet? Or can someone else tell me how to optimize the values for 20 volts on both strings?
2) If I can't use separate voltage on each string, can I use a 20 volt power supply, and then a zener diode (or perhaps something else?) to get 10 volts for the other string?
Any help would be appreciated.
I'm trying to piece together a lighting system for growing plants in sterile tissue culture; LED illumination is ideal, as we don't need the intensity used in other settings (for growing mature plants, for example).
I've decided on going with Osram Golden Dragon Plus LEDs, using two different models- one peaking in the red, one peaking in the blue. Reds run 2.15 volts, and I'm going to run them in a series of 9; at 700 mA each, that works out to about 14 watts (according to the calculator at http://led.linear1.org/led.wiz).
The other string is blue; they run 3.2 volts, and I want 1/3 as many as reds; so, with 3 blue LEDs, running at 400 mA, consumption is 4 watts. The problem is, they're at a separate voltage (10 volts).
Last night, I thought I had a solution using the website above using 20 volts for both, but Firefox crashed and I lost everything. I can't figure out how to run both strings off of 20 volts without huge resistors- and lots of wasted power.
My questions:
1) Is there any sort of way to figure out how to optimize efficiency without plugging in these numbers manually- maybe a spreadsheet? Or can someone else tell me how to optimize the values for 20 volts on both strings?
2) If I can't use separate voltage on each string, can I use a 20 volt power supply, and then a zener diode (or perhaps something else?) to get 10 volts for the other string?
Any help would be appreciated.