LED Light Build Log - In Pre-Production

[Shpongled]

I am NOT an electronics expert. If you see errors in my posts please correct me so they can be fixed.

As some of you know I am working on designing a small LED grow light. This is purely a hobby interest for me and I am not looking to sell a product. Because of this any info I find or learn will end up right here for anyone that's interested. Currently I am in the research phase and I will document the progress in the first post of this thread. I will be using the second post for my appenidx. Any interesting websites, component sources and otherwise useful info will be there.

Enjoy!

11/15/09
My research is starting to pay off. I have finally found some high power LED's in the 660nm range (Dark Red). There seems to be a growing number of producers of LED's for the horticultural industry.

One such product is the LEDEngin 660nm Deep Red LED.

Press Release: LEDEngin 660nm LED

Mouser - LEDEngin 660nm RED LED:
5W ($11.70):LZ1-10R205 LedEngin LED High Power (> 0.5 W)
10W ($32.50):LZ4-40R210 LedEngin LED High Power (> 0.5 W)

Along with the Red 660nm spectrum range the Blue 453nm range is also important. LEDEngin also has 5W and 10W emitters that are close.

Mouser - LEDEngin 465nm BLUE LED:
5W ($9.90): LZ1-10B205 LedEngin LED High Power (> 0.5 W)
10W ($32.00):LZ4-20B210 LedEngin LED High Power (> 0.5 W)

Here is a link to all of the high power LED's from LEDEngin: LedEngin LED High Power (> 0.5 W)

To fill out the spectrum I will probably add few more colored LEDs but I will also be adding some Warm and possibly Cool White LED's.

This following site has some great prices on Luxeon 1W and 3W Warm White LED's. Currently they are selling the 1W for $3.50 and the 3W is $4.90. This is roughly half the price of elsewhere.

Luxeon 3300K Warm White LED:
Specs: PDF
Purchase: Luxeon LED


There are multiple ways to drive these LED's. You can use a simple resistor for each string of multiple LED's or use a LED Driver which will operate at a higher efficiency (90%+).
You can find drivers that operate off of either AC or DC inputs so you can find one that's right for your application.

This site sells many different LED drivers: LED Drivers - Constant Current Drivers - LuxDrive - LED Supply.com

You want to match the output current (mA)of the driver to match that of the LED's. For example the Luxeon 1W LED's have run at 350mA so you will need a driver that outputs the same value. Along with that the total output voltage limits the total number of LED's.


I am will be running my LED's in series which meas they are all connected to each other and the first and last LED is connected to the power supply.

Here is an illustration:

The image about is an example of LED's in series using a resistor to regulate the input current. The resistor is not necessary when using a LED Driver.

When LED's are in series the forward voltage(Vf) is cumulative for each LED. If the Vf of these LED's is 3.5V the total Vf for this series would be 10.5V. The current draw in a series is the same across the whole series. So if each LED draws 350mA the draw for the whole series would still only be 350mA.

NOTE: In my examples all of the LED's in the series are of the same type. I don't know what should be done if you are mixing and matching different LEDs with different forward voltage or current.

Time for another example:

Lets say I am using BuckPuck 350mA DC LED driver powered by a regulated 24V DC power supply. The BuckPuck has to have an input voltage that is at least 2V higher then the total Vf used by the LED's. That would mean the total voltage available to my LED's would be 22V.

You now need to look at your spec sheet for the Forward Voltage of the LED's you are using. The forward voltage(Vf) listed on the spec sheet is the average value so this could be a little different on each LED. You can test the LED's with a multimeter to see the actual voltage drop or just go by the spec sheet. If you are running multiple LED's on each driver this is not as big of an issue. The differences of each LED should even out.

Now lets say the forward voltage(Vf) of each LED is 3.5V. Remember my driver can provide a max of 21V.

This would mean I could power 6 LED's from each driver:
3.5V+3.5V+3.5V+3.5V+3.5V+3.5V=21V

In theory this is perfect but because of the differences in the forward voltage of LED's its a little tight. A small difference in the actual numbers could cause me to overstress my driver. Remember to keep that in mind, a little headroom is always a good thing.

To continue this lesson, if you are using a DC LED driver you will also need a AC - DC REGULATED power supply.

Power supply: 24VDC @ 4.2A POWER SUPPLY

So now we know that each 350mA BuckPuck driver can power up to 6 of my chosen LED's but how many BuckPucks can the power supply support?

Remember that when running LED's in series the same current flows through all of them. In this example the LED's will draw 350mA.

Each string will use 350mA (.35A) and the power supply can provide up to 4.2A.

4.2/.35 = 12.

I can run 12 series of 6 LEDs for a total of 72 LED's off of the power supply.

Each series will require its own driver but all 12 drivers can be powered by the one 24V 4.2A power supply.
11/16/09

I have been in contact with two LED suppliers today and am making progress.

First up is AOPLed.com
They are a US based manufacturer of high power LEDs. The have a few that they specifically marked for the horticulture industry.

The two 660nm LED's they produce are:
PU-1WRE 1W 660nm LED: AOPLed.com 1 Watt High Power 660nm True Red LED Lamp, 350mA, High Temperature, High Driving
L-995PUSRC: http://www.greenpassion.org/attachme...1&d=1258417577

I was told they both emit 6-8lm which is a bit disappointing compared to LEDEngin. The only place I can find them is directly from aopled. You will need to email them to order.

The pricing I received was:
L-995PUSRC - $1.65 (no min)
PU-1WRE - $2.80(min 100)

I am getting 5 of the L-995PUSRC next week for testing. I will snap some pics when I have them connected.

I also have been in contact with Roithner-Laser. They are based in Austria and have a decent selection of LED's. You can see their full list of high power LED's here: high power LED, led array, white power LED, power chip led, 350 nm LED, 370 nm LED, 380 nm LED, infrared power LED, power LED illuminator, TO-66 LED, LED current driver, LED heat sink, LED cooling fan

I am waiting on prices.

I hope some of you find this post useful. I will be updating it regularly as I source more parts, design the circuit and build my prototypes.

Please feel free to add any info or parts that you find! I am finding it tough to source good LED's so any help is appreciated.


All calculations are for the specific values in my examples. Make sure to use the correct values for the components you are using.

[Shpongled]

Appendix

Component Sources

Solidstate-lighting.com
Luxeon Star LEDs, High Power LED Products & Accessories
Cutter Electronics
Luxeon LED
Cutter Electronics (Australian)


Absorption Spectrums of Plants



Good article on PHOTOSYNTHESIS


LEDEngin Product Charts







Luxeon, Cree, SSC & Osram LED Bin Lumen Output

[PhotonCollector]

As a design engineer who has worked with several start up companies, I wish you well.

I would also like to stress that if this is a hobby endeavor, go for the gusto.

If you are trying to compete with the big boys, to bring a product to market, you will not be the first. Some people think outside the box, Bill Gates & Steve Jobs come to mind.

As well as numerous others not so well recongized individuals. I have started up many plants and shut down many plants.

If you have very deep pockets, you might beable to come out with a competitive product, myself I will research existing products and invest my money with an established product.

I wish you well.

[Shpongled]

Nope not trying to bring a product to market. This is simply a hobby . Im just trying to get some info out for people and get some help for myself. Looking at the math just the price of the components for a comparable product would be more expensive than buying one.

If I could source cheaper LED's I might be able to save a little money but it wouldn't even be close if I calculate in my time.

Im glad you stopped by, it could be hand having a product engineer around ;). Pull up a chair and stick around. You input is very welcome at all stages of this project.

[NoBsplz]

Now this...is going to be cool

[Shpongled]

Today's Update, also in first post:

11/16/09

I have been in contact with two LED suppliers today and am making progress.

First up is AOPLed.com
They are a US based manufacturer of high power LEDs. The have a few that they specifically marked for the horticulture industry.

The two 660nm LED's they produce are:
PU-1WRE 1W 660nm LED: AOPLed.com 1 Watt High Power 660nm True Red LED Lamp, 350mA, High Temperature, High Driving
L-995PUSRC: http://www.greenpassion.org/attachme...1&d=1258417577

I was told they both emit 6-8lm which is a bit disappointing compared to LEDEngin. The only place I can find them is directly from aopled. You will need to email them to order.

The pricing I received was:
L-995PUSRC - $1.65 (no min)
PU-1WRE - $2.80(min 100)

I am getting 5 of the L-995PUSRC next week for testing. I will snap some pics when I have them connected.

I also have been in contact with Roithner-Laser. They are based in Austria and have a decent selection of LED's. You can see their full list of high power LED's here: high power LED, led array, white power LED, power chip led, 350 nm LED, 370 nm LED, 380 nm LED, infrared power LED, power LED illuminator, TO-66 LED, LED current driver, LED heat sink, LED cooling fan

I am waiting on prices.

[Shpongled]

Here is a great page with great DIY LED grows:
Growing Marijuana with LED, Growshow

[howlin420]

i do wish you well .and thank you for sharing your info

[Shpongled]

Thanks, I realized today that I can no longer edit my first two posts. This kinda kills my formatting but I will survive. I am just going to make a new post for each update.

11/20/2009
Last night I discovered that LEDEngin has released a new LED for horticultural uses. it is a Far-Red 740nm 5W diode. I was intrigued but did not know what this particular wavelength was used for. I finally found some very good info in this article: http://irrecenvhort.ifas.ufl.edu/spe...Plas%20Con.pdf

One way that plants regulate growth and other functions are through a system of sensors that detect specific wavelengths of light. Without going into too much detail, it is possible to flash light in the 740nm range at the end of a light cycle to reduce the dark time needed by the plant in flowering. There have been people that have tried this with pot here: Phytochrome Questions - Cannabis-World

Sadly the opinion is that its not worth the trouble so I wont be bothering. If you know any other reasons to use these LED's let me know.

[JBeezy87]

http://www.growlight.cn/grow/High-po...tion_study.pdf

This is a slideshow from a lecture about a University Study, I found the actual study online but it costs money to view and I don't wanna pay. It's on using LEDs in wavelengths of 660, 640, 735, and 455 only. They/he used the lights on both lettuce and radishes in 4 different setups (varying amounts of each wavelength) and called them EXP1 through EXP4. In EXP2, he flashed the plants with 735nm light at the start of their sleep cycle and it didn't help. But in EXP4, he flashed the 735nm at least 4 hours after the sleep cycle for 1 hour and it really helped the radishes grow.

In this experiment, he didn't use the 730nm light to shorten the dark period, but the flash in the middle of the night really helped the plants grow much bigger. Just a thought.

I'm doing lots of research before building something similar to the DIY panel on ledgrow.eu except I will be using 660nm and 640nm in place of the 620nm he is using and include a tad violet (395-430), maybe a few 1W UVB leds. The Cool White leds are a great idea because they cover all the middle colors (green through orange) that plants actually do need and use.

[JBeezy87]

Actually upon looking at the actual LED he used for the 640nm component in the experiment, I discovered that the led is rated at a peak of around 620.

I can't find a high-power led rated at 640nm with 5W or 10W of power on Google, either.

Hmm...

[Shpongled]

You would want leds with a peak of 660nm for optimum plant growth. The only good options I have found are the LEDEngin ones I have listed on my first post.

[JBeezy87]

Yeah I know about those.

I looked at your warm white LED and the Specs sheet says discontinued. This means that there are better, more efficient White LEDs out there with higher luminous flux. And since delivering as much energy to your plants is your goal, more lumens is better.

Look at this Cree XLamp XP-G: http://www.cree.com/Products/pdf/XLampXP-G.pdf

It's cool white instead of warm white but they have a luminous flux around 130 lum at 350mA (they run up to 1 Amp I believe), and that's a lot for LEDs. So maybe you could use two of these and just one blue, since the cool white emit a lot of blue. (or other numbers, I just remember you saying small grow light).

How many LEDs were you planning on using? All 5W? All same current? Just wondering, I may have some input.
Were you going to include any wavelengths shorter than your blue led? maybe Longwave UV? LedEngin has some in the range of 390-410: http://www.ledengin.com/products/5wLZ/LZ1-00UA05.pdf if you like there LEDs

[Shpongled]

I did not think about using UV. Do you think it would be beneficial?

Lately I have been looking into 1W Edison Opto LEDs but I am having a hard time finding a supplier. I have emailed one in China with a small minimum order quantity of 50.

The two main LED's im looking at are:
EFED-1AE1: 1W 450-470nm Blue LED
EFEE-1AE1: 1W 650-670nm Red LED

The

[JBeezy87]

I would go with different LEDs. Since you are making a small panel, I would suggest using 3W or 5W leds (5W preferred) so you can put out more energy with each LED (The 10W versions of LEDEngin's Deep Red and Far Red LEDs cost 3x what the 5Ws cost on mouser so price-wise those aren't the best). Remember you're using high-power LEDs over 5mm high-brightness LEDs because they put out more energy per unit. Why stop at 1W when 5W are fairly affordable ($10-12 on mouser for 5W LEDEngin's on stars).

(I will be looking at LEDEngin LEDs for this post because you expressed interest in them earlier)

Take a look at this Constant Current power supply: LPC-20-700, Mean Well LPC-20-700

Output Specifications: Output Voltage: 30 Volts DC Voltage Range : 3~30 Volts DC Current: 700mA Power: 21 Watts
Input is universal AC.
Up to 30VDC so plan to not go over 27 or so and you're good unless you can test each led for it's exact Vf.

That's at least 9 5W Deep Red LEDs (2.7 forward voltage at 700mA http://www.ledengin.com/products/5wLZ/LZ1-00R205.pdf). And running these 1A LEDs at 700mA will help control heat issues and extend the life of the LED.

(Typical) Forward Voltages of useful 5W LEDEngin LEDs at 700mA:

LZ1-00R205 Deep Red (660) - 2.7
LZ1-00R105 Red (630*) - 2.5
LZ1-00DB05 Dental Blue (460) - 3.5
LZ1-00CW05 Cool White - 3.5
LZ1-00UA05 UVA (390-410 depending on bin) - 4.0

*Relative Spectral Power chart for this LED suggests a peak just over 625nm.

I included the UVA LEDs because your "Absorption Spectrum of Plants" chart shows a mini-peak for Chlorophyll-a at 410nm.

The Cool White LEDs will deliver light in between the Red and Blue due to phosphors. Warm White leds will give more mid-range light and less blue light but the phosphors used on this led absorb more energy (that's how the wavelengths shift) and are less efficient. I would use cool whites over warm whites.

Depending on the sized of your array, I would plan for one Dental Blue, One UVA (Bin U8 for peak closer to 410), one cool white, two Reds, and two Deep Reds as the minimum. If you want more LEDs, add more Red and Deep Red, maybe another cool white and dental blue if you get ambitious. The Cool White, Dental Blue, and UVA LEDs cover the 400-470nm range, the cool white deliver light in the 480 - 620 range, and the reds cover the rest. This way you deliver the full visible spectrum to your plants.

The Reds are much more efficient than the Deep Reds so using two of each gives a balance between total light output and output in preferred wavelengths. Unfortunately at this time, you gotta make this sacrifice because the Deep Reds and not the most efficient (higher voltage drop at a longer wavelength = less efficient).


Voltages sum to around 21 with the original 7 Leds I proposed so these room at add more leds with the same power supply. Adding one more Red and one more Deep Red adds to 26.6 so that one supply can power 9 leds.

And the supply is cheap ( like 16 or 17 dollars) so you can probably afford more than one if you want to add more leds at a later date.

Also, some Cree and Luxeon Rebel LEDs may deliver more radiant power than the LEDengin leds. If this sound like the path you want to take, I can help you find some efficient ones.

You can mix and match different LEDs from different manufacturers. They just need to be able to run at 700mA. Also, if two blue leds deliver the same radiant power at the same wavelength but one has a lower forward voltage (3.2 vs 3.6) the LED with the lower Forward Voltage is more efficient and should be used. Be sure to compare Forward Voltages at 700mA (may need to look at a graph in the LED's data sheet to figure it out).

Let me know what sound good and what doesn't work for you.

[Shpongled]

Yea that sounds good. Is there any reason not to use the buckpuck drivers? They offer a bit more output voltage for the same price.

I like the idea of using some regular red LED's to boost output. Also do you have any knowledge of the far red leds? Some of my reading about the photchrome system leads me to believe that these could be detrimental.

[JBeezy87]

In order to use the buckpuck drivers you would need to also buy a power supple. This one which has an output of 24VDC and 1.5A (S-40-24, Mean Well S-40-24) costs $21. Add in the two buck puck drivers (I'll use 700mA each: BuckPuck 700mA DC LED Driver (PCB Mount) [3021-D-E-700]) and at $18 each your total is $57.

Two of those 700mA supplies that I showed you (which you can plug into you outlet, $17 each) and your total is $34 : LPC-20-700, Mean Well LPC-20-700

If you need one at 350mA it's also $17 : LPC-20-350, Mean Well LPC-20-350 and that supplies up to 48VDC. Then you could mix 5W at 700mA and 3W at 350mA.

Here's one at 1A, cost $25: LPC-35-1050, Mean Well LPC-35-1050 up to 30VDC.

For a small board you would only need two of these (at most 1A and 700mA = $17+25=$42) and that is probably the most cost effective way to go.

And on the topic of heat-sinking, look at this page: DIY LEDs - The write-up - Reef Central Online Community

It's a very clean project, and he glued the 24 LEDs extremely close together on the heatsink, which is cooled with the fan.

The heatsink he got here: HeatsinkUSA, llc
Just click on the X-inxh profile option on the left and then select the length you want. You would probably want the 8.460 inch option since the 10 inch heatsink is over an inch taller.

If this is in your budget range (8.460 x 10 inches is $22.50) it's probably a great way to heatsink your LEDs.

[JBeezy87]

On far red leds look at this study: http://www.growlight.cn/grow/High-po...tion_study.pdf

I already posted it up above but here's more on what I get from it.
On page 15, the green mass production of EXP2 (where he exposed the plants to 730nm light at the START of their sleep cycle) is extremely small. But in EXP4 these is a lot of green mass production (this is where he exposed the plants to 730nm light from 2-3AM, in the middle of their sleep cycle). There is more production for Radishes with this exposure then there is for lettuce.

So for mj, this exposure may or may not help, but it doesn't seem to hurt the plant. The exposure just needs to be a few hours into the sleep cycle. Not at the start of it.

On page 17, the concentrations of chlorophylls a+b shows that the exposure didn't really boost photosynthesis for lettuce, but it did for radishes. (EXP4 is slightly higher than EXP1 for lettuce, but much higher for radishes).

Another interesting thing about page 17 is that EXP2, which had extremely low green mass production, had lots of chlorophyll in lettuce and some in radishes.

The difference is that lettuce doesn't flower in response to length of night, and therefore, phytochrome. Radish doesn't either. Cannabis does.

So it seems that stimulation with this light helps photosynthesis, when it is occurs a few hours into the plants sleep period.

This would be something I would attempt after building my light and testing it on a few grows. Keep really descriptive grow journals. Then add the 730nm light in the middle of the sleep cycle and see how your plants' growth is affected.