[AvidLerner]

Hey all! I hope everybody had a good weekend. Mine was filled with nice weather, good friends, and a few IPAs.

On Saturday, I got things rolling on this Samsung LM561C mid-power LED build and I’m liking what I’ve seen so far. I’ve tested half of the strips and am happy to say that I’ve got no failures yet, and they seem to be very uniform in terms of brightness and voltage drop.

All 25 strips lined up.

Close-up

Testing out different power and spacing. Holy hell these things are bright.

I’ve been mulling over what I want to do with this build for a few days, but came to a decision this afternoon. I could make one big-ass mega light, but I don’t really need a billion PPFD for anything right now. I DO intend to jam all the strips together just for shits just to see what kind of PPFD I can get out of all 25 together, but I won’t be keeping them as one light.
The Plan

What I’m planning on doing is splitting the 25 strips into 4 separate lights, each with 6 strips (I’ll keep one strip as a spare). I’ve done some really quick testing, and I figure if I can hang each light about a foot above the plants I’ll be growing, I should get at least 300-400 PPFD. This might be a little low for some types of plants, but not the types I want to grow with these.

One week ago, my work started a weight loss challenge and I signed up. I managed to eat pretty well for the first week, but have realized I’m going to need an absolute fuck-ton of salad on hand if I’m going to pull this off. With that in mind, I’m going to use my 4 new lights to grow leafy greens in big plastic totes, Kratky style (I might have some questions for you, Noel!). I’m hoping I can fit 6 plants ( in 3″ net cups) per tote, so I should end up with 24 delicious plants that I can snack on every night at midnight before I cry myself to sleep.
Power

I’d like to power all 4 lights off of a single driver to keep things simple.

Each individual diode has a maximum current of 200mA. On these strips, there are 3 parallel strings, each containing 8 diodes wired in series, for a total of 24 diodes. Since the 8 diodes in each string are wired in series, the max current of each string will be the same as the max current for a single diode: 200mA. Since there are 3 of these strings in parallel, we add the current from each string to get 200mA + 200mA + 200mA = 600mA max current for the whole strip.

The wiring diagram for each strip. There are 3 strings in parallel, each containing 8 diodes in series. The 2 positive connectors are wired together as are the 2 negative connectors.

At 600mA, the forward voltage of each strip is 24.2V.
I’d like to run these diodes at about half power, or 300mA per strip. Each of the 4 lights will have 6 strips in parallel, so I will need 6 x .3 = 1.8 Amps per light.
I’ll wire the 4 lights together in series, so my total voltage drop will be approximately 23V + 23V +23V +23V = 92V.
I’ll need a Mean Well HLG-240H-C1750 in order to provide 1.8 amps of current at 92V.

Edit 05/18/17: I ended up going with more power. I used an HLG-320H-C1750 and changed my series/parallel wiring in order to provide more power. Links to the final result are at the bottom of this post.
Thermal Management

After my brief testing, I really do think I could get away with not using heat sinks for these strips. I was getting a case temperature reading of about 40 degrees Celsius (take this with a grain of salt – I just taped a thermocouple to the solder point so there’s no way it was very accurate). That being said, I’m still going to attach each strip to a piece of 1″ aluminum U-channel. I figure that since I’m going to need to build some sort of structure for each light anyway, I might as well build it out of something that can dissipate heat.

I picked up a bunch of this U-channel from Home Depot and attached one strip to a chunk of it with some #6 self-tapping screws:

I found that despite using 3 screws, I wasn’t getting as uniform a pressure on the strip as I’d like. I had some old thermal paste kicking around, so I threw the rest on the back of the strip and reattached it. This seemed to make for a better fit, so I will be ordering a bunch of thermal paste for the rest. I’d like to just use a thermal adhesive and not have to worry about screwing the strips down, but I haven’t been able to find one that comes in a big enough package (and doesn’t cost a fortune). I may just end up doing 6 screws per strip since it’s aluminum and it’s easy as hell to drill anyway.

Edit 05/18/17: I ended up getting some decently-priced thermal adhesive for this build and went screwless.
Structure

I bought a couple lengths of 3/4″ square aluminum tube to use as the base structure for each light. Once I have the strips all mounted to 1 foot chunks of U-channel, I’ll attach each side of each channel to the square tubing. The tubing will run the length of the light, and I’ll hang the light by tying on to each corner of the tubing. Behold my paint depiction… these just keep getting better and better:
https://ledgardener.com/samsung-lm561...tting-started/

The above is an explanation for using Samsung hard strips with Constant Current Drivers or Constant Voltage drivers. I have been using both, and I the Constant Current is more efficient, but the Constant voltage is easier.

I have been playing with the flexible strips which you can cut into lengths versus hard strips with preset lengths like the article above. I have been experimenting with two predominant spectrums 3000k 90cri or 3500k 80 cri and 5000k 80cri. I have flexible strips in 3000k 90cri and they are great with NO HEAT. I mount mine on 1/8" th x 3/4" wide aluminum flat stoce and use light angles to hold it all together. The strips come with 3m mounting tape to stick to what you want. They are available in 5m to 50m amounts from $4-$6 a meter depending on how much you order. Larger orders can be processed by machine while smaller orders are processed by hand. All still great work. It was experimenting with these I decided to design and use a PCB board as well. I get the strips from Alibaba from Mufue Technologies an excellent company great folks Roget is very dependable and reliable too.
enjoy
namaste

[AvidLerner]

The two spectrum light is Constant Current and the 5000k is the constant voltage. Constant Voltage is 24v and you can connect as much as your 24v constant voltage power supply by amps can supply. I am using a 10 amp model. The second is Constant current using a meanwell HLG-185H-C1400B driver. The fixture has six strings of 49 diodes each at 2.9 Vf for a total of 149Vf with six parallel strings for 1200mA max average amps 1050mA
namaste

[AvidLerner]

The average wattage for the Continuous Current strips is about 32-36w per 5 meter strip. Not bad for wattge but the growth at that rate is great. Here is a garden shot of some veggie4s under the CC strips with 3000k 90cri and 5000k 80cri
namaste

[AvidLerner]

I have built two flexible strip lights so far. One is over my veggies the other is in my Veg. The strips are made with 70diodes/m for about 32w.

The first light I used 7 segments for a total of 49 diodes with a Vf; forward voltage of 142.1v and 200mA per string. I connected six strings together in parallel which adds the amperage but not the voltage, so I have 6x200mA or 1200mA total available current. For this light I am using a HLG-185H-C1400B driver so I can drive the diodes closer to 200mA current for about 170w.

The second light has ten segments in series for 203Vf @ 200mA. However, now I am using a HLG-240H-C1050B driver so I can only deliver a max of 1050mA but the circuit can only carry about 100mA per string because I have the circuit with twice the current demand so I am driving the diodes at 100mA real close to the max of 200umol/w which the plants love to veg under. The measured wattage is 32 watts at 300mA.
namaste

[AvidLerner]

Wonder what you can do with Samsung flexible strips?

build a Quantum Board Killer

Tired of waiting for a Quantum Board ? No problem.
First. The science behind the Quantum Board is they use 38 diodes wired in series with 8 strings, this is called 38S8P or 38 diodes wired in series and 8 strings of wired in parallel.

Second. Flexible Samsung strips are $6/m average order 40 meters. 1 meter is made up of 10 segments of 7 diodes each. Working with strips segments I would recommend using 6 segments for each string. However to compact the size I would recommend cutting the 6 segments in half into 3 segments each and rewire them in series making them 12” long by two strips wide. Do this for all 8 strips. A 40 meter reel of Samsung LM561C S6 bin diodes holds 10 segments per meter x 40 meters or 400 segments. It takes 48 segments to make one board. A reel of 40 meters might run $300 shipping included. For $300 you can build 8 Quantum Boards.

Third. I decided to use 3000k 90cri and 5000k 80cri for all of my builds with Samsung flexible strips. So I cut my 8 segments into three segments each and mixed the spectrum on each column. I provided some pictures to show you how I applied the strips to a Cookie Sheet and connected it to a HLG-185H-C1400B meanwell driver and I have a 150w GrowGreen Flexible Strip Board.

Parts:
1. 24 segments of 3500k 90cri cut into 12” lengths at 3 segments each. $15
2. 24 segments of 5000k 80cri cut into 12” lengths at 3 segments each. $15
3. 22 gauge wire to connect series strings and parallel strings. $ 5
4. 1 Meanwell HLG-185H-C1400B led driver (reuse) $58
5. 1. Cooikie sheet 12” x 13” flat from hardware store $12
Total cost $105

Samsung strips can be gotten at Mufue Technology at Alibaba ask for Roget
Enjoy your DIY Quantum Boards
namaste

[AvidLerner]

If you are interested in building the larger Quantum Board QB304, all you have to do is the following 21S8P parallel 2P two modules connected in parallel:
1. Use 3 segments of 21 diodes Vf 63v @ 200mA
2. Wire 8 strings in parallel 63Vf @ 175mA
3. Make two of these modules.
4. Wire the two modules together in series, and connect to a HLG-320H-C1400B driver and you have a QB288 Killer too.
easy
namaste

[OG Expressions]

Originally Posted by AvidLerner

If you are interested in building the larger Quantum Board QB288, all you have to do is the following 21S8P parallel 2P two modules connected in parallel:
1. Use 3 segments of 21 diodes Vf 63v @ 200mA
2. Wire 8 strings in parallel 63Vf @ 175mA
3. Make two of these modules.
4. Wire the two modules together in parallel negative to negative, positive to positive, and connect to a HLG-320H-C1400B driver and you have a QB288 Killer too.
easy
namaste

What is the total cost of your board you put together?

[AvidLerner]

It cost me about $45. I bought the reels of diodes already but I used about 5 meters worth, I had the wire and the driver and I bought the cookie sheet, my GF would not give me one
namaste

[OG Expressions]

Originally Posted by AvidLerner

It cost me about $45. I bought the reels of diodes already but I used about 5 meters worth, I had the wire and the driver and I bought the cookie sheet, my GF would not give me one
namaste

You mounted the LEDs on a cookie sheet? Oh this is not something i would be interested in my mistake though thank you for explaining.

[AvidLerner]

Originally Posted by OG Expressions

You mounted the LEDs on a cookie sheet? Oh this is not something i would be interested in my mistake though thank you for explaining.

I could have bought a fancy heat sink, but perhaps you missed the point, cheap, effective, efficient. You can mount on a bat wing reflector, I also use aluminum flat stock. You could also mount them in a spiral manner on a flat sheet. Many options available, that is what DIY is all about run what ya brung, like we say at MC rallies. I just hope I inspire you to build your own DIY QB Killer on the cheap or any way you want.

The key is understanding the science behind the design do you can do your own thing like I do. That is why I share. Sharing is Caring.
namaste