knna

There is little difference in spectrum between LW and LUW. I carry LUW, currently. Its true that slighty warmer tones have better spectrum for us, as they emit more in the yellow and less in the green, and emits more far red. But currently, efficiency of warmer tones is way lower than ultra white ones, for all manufacturers.

Usually, when I have to choose between better spectrum and efficiency, I choose the second. For me, the ideal point of compromise is to get bins with CCT between 5000 and 5700K, which still is coolwhite, avalaible on the highest bins, but the spectrum is better than cooler tones of white. But getting at a time the best luminous bin and the right color range is difficult.

The only way of getting a reliable electric contact, good mechanical bond and thermal dissipation is by soldering. There is no magic solutions to this. There is alternatives, but all have their disadvantages. Soldering the Golden Dragons is very easy. Their leads are already pretin, so with just putting the solder iron tip on the copper tape but touching the lead, for 3 seconds and adding the tin, the soldering point is done. It get me some minutes to solder a full lamp with more than 100 GD. Do it near the open window with a fan blowing, and you wont be concerned at all about vapours.

Many people without any previous soldering experience has soldered the GD lamps without any problem on the spanish forum. About 100 growers has built their one DIY LED lamps and until now, no one had problems soldering or mounting the lamp. At least half of them hadnt soldered before. People had problems soldering the Cree, thus we give up using them.

I tried this past weekend that somebody record me on video building a LED module, but nobody has camera. Now Im going to take two free weeks, but when I come back, Ill try again to do a video, so people may see how easy is the soldering proccess.

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ProBudster

Hi Knna Awesome post! I just got a few questions if I got a driver with
Output Current: 700mA
Input Voltage: 120VAC 60Hz
OutPut Voltage: 7.8-24.6VDC
Output Power: 17W
and im interested in using K2's But the specs are different on the different colour K2's is it still possible to use the same driver for all the bulbs if the specs on the K2's are:
-Blue
21 lm @ 1000mA
35 lm @ 1500mA
1500mA - Max Drive Current
3.85Vf - Forward Voltage
470nm - Color Temperature
-Red
45 lm @ 350mA
75 lm @ 700mA
1500mA - Max Drive Current
3.4Vf - Forward Voltage
627nm - Color Temperature
-Cool White
100 lm @ 1000mA
130 lm @ 1500mA
1500mA - Max Drive Current
3.85Vf - Forward Voltage
6500K - Color Temperature

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knna

Yes, its possible to use different color LEDs from the same driver, as far as its a constant current one (as yours).

But then, you run all colors at same current. You dont have a ability of using the optimal current for each color or adjust the emission spectrum by varying the current of one color (or some).

But in order to take advantage of that, you would need current adjustable drivers. So in case you dont have them, there is no any problem or disadvantage running different colors from same driver.

But be aware that driver has a max output of 24.6V. The sum of the Vf of all LEDs conected to it can be higher than that. Its a 17W max driver, so I think you are going to need a buch of them except if your grow area is very, very smal.

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OzricTentacles

The major problem for using the led at their efficient montage is the distribution of colors for 2 or more current. Actually i try to figure a good circuit for using 2 drivers at 600mA and 700mA. I will use a larger copper tape to trace 2 ways and pass thrue around the heat disspation pad by cutting the tape. I figure to use soldered wire to make bridge because i think it's not possible to superpose the copper tape.

If i use 45 red 10 white and 5 blue, I need to distribute 1 white for average of 4 or 5 red and 1 bleu for 9 red.

It's difficult to verbally understand, but soon i will post a CorelDraw graphic about that.

ProBudster

Thanks for the speedy response I appreciate the help. Im not into electronics so might need a bit of help with understanding the concepts. Cool so now Im looking at two drivers a 25W 1050mA Driver and 17-Watt LED Driver with output current 700mA, output voltage 7.8-24.6VDC

Red leds are 700mA, 3,4Vf 0.7*3.4= 2.38W with 12 leds=28.56W
Blue leds are 1500mA, 3.85Vf correct me if im wrong but I think with the 1050mA driver then 1.050*2.695= 2.83W with two leds=5.66W
White leds are 1500mA, 3,85VF so im guessing 1.050*2.695=2.83W
with two leds=5.66W

So if I use one 25W 1050mA driver and two 17 Watt 700mA LED drivers could I power
12X Red 2XBlue and 2XWhite can the Wattage of the driver be higher than the Wattage of the lights without blowing them or do you have to have higher wattage in leds?

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knna

Going it is easier, OzricTentacles. You just need to put a layer of kapton tape between two copper traces that cross, thats all. The kapton tape is an excelent electrical insulator. Flexible circuits use alternated layers of copper and kapton to build them, and they can have up to 8 layered circuits.

I didnt want to shake people's heads more than needed, so I havent explained in detail how to build a double circuit on the panel, but I did on the tutorial of the spanish forum, with pics. Building a double circuit requires more job, but on the other hand, you can use the copper traces for electrical conections as extended thermal paths.

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knna

Instead of using Watts, its easier to use just Volts. Watts=Volts*Amperes (for DC current). So if you take out Amperes of the equation, its equivalent.

So, you have 12 reds that run at aprox 3.4V. Thus, they sum 40.8V. As the 700mA driver gives up to 24.6, its insufficient to run all those 12 LEDs. Each 24.6V driver can run a max of 7 of your reds (7*3.4=23.8V). So you will need two of these drivers to run the red LEDs, with 6 on each driver. You can use up two more red with same drivers.

For the Blue and White LEDs, they run at about 3.6-3.7V at 1.05A (1050mA). You have put a Vf at 1.05A of 2.695, that I think you have calculated by derating proportionally the Vf at 1500mA. It dont work that way, Vf varies way less than If: their relationship is exponential, not lineal (check the first pages of the tutorial for more detailed explanation about it).

So 2 Blues and two Whites needs about 14.6V in total. So you can drive then with one 1050mA driver. In fact, you still have room to drive up to 2-3 more LEDs from same driver.

You need to charge the driver with a total Vf load into its specifications. In your case, they need a minimun of 7.8V and a max of 24.6V. The only thing you must ensure is that the sum of the Vf of each LED conected to the driver is between those figures.

PS: always take in mind that Vf from datasheets is orientative, as it represents tha average Vf. Actual Vf of a given lot of LEDs surely will vary. Often, just a little, but it may vary for some tents of Volt sometimes. At the end, to determine the final configuration, you need to measure actual Vf of the LEDs to be used Luxeon LEDs are known for start with an higher Vf during first 1000h of use and then it drops, up to some tenths of Volt for a given If.

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OzricTentacles

For understand electricity i use water comparaison, each led is like a hole on a hose, the voltage is like the diameter of the hole. Each led require enough pression from the driver for having the same stream level for an harmonic fountain.

By the way ;-) Where you find your variable amp. driver ?

You-are not in vacation ? ;-)

Is it possible to superpose tape for drawing a complex circuit without loosing conductivity, for resistance of <0.5Ω is the resistance adding and will be <1.0Ω after one superposition ?

Buenas vacaciones

knna

Electrical resistance added is minimal. I measured it on a 120W LED lamp, 5m long, using 6mm wide copper tape (instead of 3mm, as I use almost always) and the impedance due all the copper tape was 0.1Ohm. So electrical resistance is negligible. Sandwiching some layers of copper and kapton dont add more resistance than paralell copper tapes of same lenght, on a measurable way.

I ordered my adjustable current drivers by custom demand. In general, comercial driver's manufcturers choose to do drivers with tapped max output voltage due two reasons: easier homologation to safety laws and to obligue you to buy more drivers Letely Im playing with some drivers I import from Taiwan that are working very well, although the current range is lower than I would like.

I went by other way myself. The circuit is not hard to build, but if I dont post schematics of it is due for any individual is going to be harder to build it manually and almost sure that more expensive, due the huge profit margin that electronic components shops charge for individual component that are very cheap when you buy it on large amounts from manufarturers, Capacitors, resistors, etc, costing cents on the industrial level cost near 1$ when you buy it at the retail level. So buying the built circuit is almost always cheaper than building it on your own. Just the MOSFET and the inductance probably will cost you more than the assembled driver.

PS: Ill go on Wednesday

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Them

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