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lighting LED Grow lights

I'd start now.

To figure out what you want I'd build a 12 or 18in square box or get a similar sized container to play with.Paint the inside of the box white.
Buy a bunch of 5mm LEDs and 6 or 8 3X4in perf boards.

About 100 5mm LEDS fit on a board with about 28 resistors.

To play with at first I'd build 6 or 8 panels in 430nm , 470nm , 625nm and 660nm.
My panels are red to blue in whatever worked out to put as many LEDs as I could fit on the board.
You can also make each board with all of 1 wave length on them...

I probably have between 3/4 to 1/2 red to blue.

Get as high a lumen and as small an angle LED as you can find,actually I like from 25-30 degree angles.

Lable your panels as to what wave lengths are on them.

Put a hook/sprout inside the box and see what panels it goes for and watch it grow...

I like putting 4 panels over the plant and 1 on each wall of the box vertically.

make the panels so you just wire nut them together so you can move them around in different combination.

Different LED wave lengths will be different mcd/Lumens.

You'll eventually find out what ones work above or on the sides best.

Whatever panels your plant seems to like best you can put over the plant rather than on the sides.

Figure out your resistor value here for LEDs.

http://led.linear1.org/led.wiz

Figure out a ballpark Lumen for LEDs here.

http://led.linear1.org/lumen.wiz

Resistor colors/value

http://www.dannyg.com/examples/res2/resistor.htm



Assembling boards.

Check data for your LEDs.

Example:
Led is usually rated at 3 voltage variations-min. typ. and max.
Use Typ. or min.

MA is the amps you run them on.

Example of data:

Part Number: RL5-B5515 - Super-Blue LED (GaN)
absolute maximum ratings: (TA=25°C)
PARAMETER SYMBOL RATING UNIT
Power Dissipation PD 120 mW
Continuous Forward Current IF 20 mA
Peak Forward Current (1/10th duty cycle, 0.1ms pulse width) IFM 50 mA
Reverse Voltage VR 5 V
Operating Temperature TA -40~+85 °C
Storage Temperature TSTG -40~+85 °C
Reverse Current (VR=5V) IR 10 µa
Lead Soldering Temperature (3mm from body) 260C (for 3 seconds)
optoelectric characteristics:
PARAMETER SYMBOL MAX TYP UNIT TEST
View Angle of Half Power 2ø1/2 30 Degree
Forward Voltage VF 4.0 3.5 V IF=20mA
Dominant Wavelength ÿ D 467 nm IF=20mA
Full Width at half Max FWHM 25.46 nm IF=20mA
Luminous Intensity IV 5500 mcd IF=20mA


See forward voltage

20ma(miliamps)

Typ forward voltage is

3.5v

Say we are using a 12 volt , 1 amp. supply.
-------------------------------------------------
You can run 3 of this particular LED on 12 volts.

10.5 volts
-------------------------------------------------
go to the calculator:

put in 12 volts - supply

3.5v - forward voltage

20ma forward urrent

3 Leds per string

-------------------------------------------------
---------------------------------------------------
You need a 82 ohm resistor for that string.
--------------------------------------------------
The string uses 10.5 volts at 20 ma.

there are 1000ma in 1 amp.(1000/20)

thats 50 strings to get to your limit of 1 amp.

150 LEDs at roughly 1.178mcd X 150= 176.8 Lumens per board with that LED.
12v X 1amp = 12 watts power used.

I don't know why but a power supply puts out unlimited amounts of 12 volts.
But you can't go over it's amp. output.

Voltage determins how many in a string.
Ma determins how many strings you can run on that supply.

From personal experiance I'd stick to shorter string because if 1 LED fails the whole string goes out.
Easier to use a 3 volt waffer battery to check individual LEDs for the bad one if you only have 3-6 out than if the whole panel goes out.

I wouldn't run stars on just a resistor.
Use a regulator/driver.LEDS are voltage/MA sensitive and a fluctuating power supply with a resistor can fry them and at the price you pay for each one ,it can get expensive.

Thats the basics in general for LEDS.
You can get into making drivers or power regulators but my typing finger is getting tired. :)

I may have skipped something and assuming I did the math right...

I just saw quite a few 10mm Leds on E Bay for about $.50 each,red and blue in 150,000mcd-190,000mcd (56.838 lumens- 71.99 lumens each) 620nm-635nm and 460nm -465nm.

5mm are any price you want to pay...200 blues for $10. , 1000 red for $20. etc.
 
Wow, thats a lot of info in one post! Thanks for the links too! I like the idea of making short strings and small panels and being able to change the configurations of the light. :cool:
 
After you play with cheap 5mm Leds and go to 1/2 or 1 watt 10mm LEDs use the 5mm panels to promote branching on your sprouts-supplamental light...

Nothing will go to waste and by starting out small you'll be more informed about how LEDs work and what you'll need for your particular needs.

One thing thats going to be strange is that LEDs are mini spotlights.

You'll find yourself putting them too close and they will only cover a small area with only the leds that are above that area.

Farther away sometimes means more lumens per sq. in./ft./whatever.

From farther away the Leds can overlap beams and add up to more lumens and a better mix of wave lengths.

You'll have to experiment with the particular LEDs you have to find their sweet spot.
 
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