Samsung LM561C Strip Build: Finishing Touches

It’s been beautiful outside this past week so it’s been tough to get motivated to finish my DIY Quantum Board build, but I got it done today. I’m eager to see how the plants under these lights do – I think they’re going to work out really well! I’ll be growing lettuce, basil, swiss chard, and kale in Kratky totes. The nice thing about Kratky is that all you need to do is plop your seedlings into little mesh pots (net cups), cut these pots into a tote lid, then fill the tote with water, add nutrients, and just monitor the pH. The roots will grow down into the nutrient solution and drink away at it as required, so no watering is necessary.

Below are the steps I took to finish this light, but first, a quick recap of my final parts list:

  • 4x 8 foot lengths of 1″ aluminum U-channel for heat sinks. I cut these into 14″ pieces for the light strips.
  • 2x 8 foot lengths of 3/4″ aluminum square tubing for the light frame
  • 5 Tubes of heat sink plaster to glue strips to channel
  • 1x Mean Well HLG-320H-C1750A to drive the LEDs at 75% of max current
  • 24x Samsung SI-B8T05128HUS  1 foot LED strips (24x LM561C diodes per strip, 4000K color temperature)
    • These diodes are incredible. For a color temperature of 4000K, the MINIMUM efficacy of each strip is 169 lumens per watt (this would occur at the maximum current of 600mA per strip at which point the diodes are least efficient). Typical efficacy is 187 lumens per watt (at 240mA of current per strip) and maximum efficacy is 206 lumens per watt (low current).
  • 22 gauge stranded wire

Gluing the Strips to the Aluminum U-Channel

I received the thermal adhesive I ordered from Amazon a few days ago. I was pretty impressed with how quickly it arrived from China. I was able to do about 5 strips per tube.

I laid this stuff on thicker than usual to make sure it stuck well. I ran a bead down the length of each strip, then smoothed it out with an old plastic card from my wallet.

Half spread out.

Once I had smoothed out all the glue, I stuck them to my 14″ pieces of aluminum U-channel. I laid a bunch of weight across the surface of the them to keep pressure on them as they dried.

The finished product: 24 LED strips on 1″ U-channel.

Attaching the Strips to the Frame

I bought 2x 8-foot lengths of 3/4″ aluminum square tubing for my frame. For now, I have not cut these square tubes, and have just attached all my strips to them. As the different plants grow to different heights, I’ll have to cut the frame into 4 chunks so I’m able to raise them as needed over each tote. The nice thing about doing this yourself is that you’re able to choose exactly how you want the strips to space out. If you wanted to light a 2×2 grow tent, you could push them all together for a very bright and compact light. I chose to space mine out to cover as many plants as possible, since I won’t need a ton of light for these types of plants.

First, I needed to mark my tubing so I knew where to screw the channels down. I lined up all 4 totes end-to-end and laid one of the 8′ lengths of square tubing across them. I marked a line over the center of each of the net cups all the way across the 4 totes.

After marking lines on the first tube, I laid the 2 tubes side-by-side and transferred all the marks over to the second tube.

I’m using 2 LED strips over each net cup, so I attached a strip on either side of each of my center marks. I started by attaching the far right strip on one end, then the far left strip on the other end. I used 2 self-tapping #6 screws per strip to secure to the frame.

My frame. Now to fill it in with 22 more strips.

All strips mounted to the frame. Ready for wiring.

Wiring the Strips

I used 22 gauge 2 conductor wire for this project. I drilled a hole in the square tubing at each set of strips and used these holes to route all my cable. Concealing the cable in the tube kept it very neat and tidy .

The holes drilled for cable management.

Fishing the cable through the holes was easier than expected.

The completed wiring. Looks like some sort of weird ladder.

Each set of 2 strips is paralleled together on the top with 2 short jumpers. The bottom terminals are wired together through a combination of series and parallel wiring.

Bottom terminals.

Top terminals paralleled.

In order to hit ~150mA per diode, I needed to wire the strips in groups of 4. Each strip was wired in parallel with the other 3 strips in its group, then each group was wired in series with the rest of the groups. Here’s the math behind it:

Internal Wiring of Each 1-Foot Strip

We’ll start with the internal wiring of the individual strips. Each strip has 24 diodes on it and these are split up into 3 groups of 8 diodes. In each of these groups, the 8 diodes are wired in series, then the 3 groups are wired in parallel, as shown below:

Single Strip Current

In terms of each strip’s current handling, 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, which is 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. I want to give it about 75% of max, which is 450mA. This current will be split 3 ways to provide 150mA to each group of 8 diodes in series.

Single Strip Voltage

Each strip has a sticker stating that at max current, voltage will be 24.2V across it. Since we’ll only be running 75% of max current, with the help of the Samsung calculator, we can guess that the voltage of each strip will be somewhere between 23V and 24V, depending on the bin of the diodes. We’ll assume the voltage will be 23.5V across each strip at this current to make things simple.

Wiring the Strips Together

We now know that we need 450mA of current going to each strip, and that the voltage across each strip at this current will be about 23.5V, so we can start planning on how to combine the strips. There are 2 options for power: Constant voltage and constant current. Either way we go, we must keep the maximum current and voltage ratings of the connectors in mind. The connectors on the strips cannot exceed 300V or 9 amps of current, so it’s important to wire them properly.

Option 1 – Constant Voltage

A very simple solution would be to simply parallel every single strip together onto a 24V constant voltage driver and dial it down to 23.5V so that the strips pull the appropriate amount of current. If you were to go this route, you would need a 24V driver that is capable of providing 10.8 amps of current (24 strips * 450mA = 10.8 amps). This would be 254 watts of power, so a good match would be the Mean Well HLG-320H-24A, which can produce 23.5V and up to 13.3A of current. You could also just barely squeeze this onto an HLG-240H-24A, but I like to have some head room in case I ever expand or change things up. Do not daisy-chain the entire run together as you will exceed the connector’s current rating. Split the circuit up into multiple runs to avoid this.

Forum user Ted built a 24 strip light using 2 foot strips and found that if he used the built in connectors on the strips for this many in parallel, there was significant voltage drop towards the end of the run with apparent dimming:


The solution for this was to avoid using any of the board connectors to daisy chain the strips, and use his own connectors:

Using push-in connectors rather than the strips’ Molex connectors.

Fixed! Now there’s a nice, even brightness.


Option 2 – Constant Current

Going constant current will require a little creativity. I decided to get a constant current driver so I can use this it for a few other different tests in the future. With these 1 foot strips, you have flexibility in which driver you can use, because you’re able to rewire them in so many different ways. If, like me, you want to drive at 75% (approximately 450mA per strip), here are some different drivers you could use:

Mean Well HLG-320H-C1400
  • Break up your 24 strips into 8 groups of 3. Wire each of the 3 strips in every group in parallel, then wire all these groups in series.
    • 1,400 milliamps divided by 3 strips equals 467mA per strip, which translates to 156mA per diode. 
    • 23.5V times 8 groups equals a voltage of 188V, which is within range of the HLG-320H-C1400 (114V-229V).
Mean Well HLG-320H-C1750
  • Break up your 24 strips into 6 groups of 4. Wire each of the 4 strips in every group in parallel, then wire all these groups in series.
    • 1,750 milliamps divided by 4 strips equals 438mA per strip, which translates to 146mA per diode. 
    • 23.5V times 6 groups equals a voltage of 141V, which is within range of the HLG-320H-C1750 (114V-229V).
Mean Well HLG-320H-C2800
  • Break up your 24 strips into 4 groups of 6. Wire each of the 6 strips in every group in parallel, then wire all these groups in series.
    • 2,800 milliamps divided by 6 strips equals 467mA per strip, which translates to 156mA per diode. 
    • 23.5V times 6 groups equals a voltage of 94V, which is within range of the HLG-320H-C2800 (57V-114V).


I opted for the HLG-320H-C1750 since I think it will be most flexible for different lights in the future. Here is a schematic of how I wired my strips up – series connections between the 6 groups of strips are shown in blue:

All I had to do was throw a plug on the power cable and I was good to go.

The finished product with a NEMA 5-15 plug terminated on the power cable . I also spliced the LED output leads onto a chunk of 22 gauge cable that attached directly to my strips.

Lighting It Up – PPFD Results

The lights are about 12″ away from the seedlings right now, and Photosynthetic Photon Flux Density at the lid of the tote is 350-400 µMol/m2/S for all 6 plants on each tote. This number climbs quickly as you get closer to the lights. I’m pretty happy with this result, as I’m able to cover 24 plants and still get solid, even coverage across them all. A PPFD of 400 µMol/m2/S will be more than adequate for leafy greens and herbs, and I should only need to run these lights for 11-12 hours a day. The total power draw is 1,750mA * 141V = ~250W.

Firing the lights up for the first time. They’re nice and bright.

The light in place over the totes. I’ll need to rig up a more permanent suspension system – especially when I chop this big frame into 4 smaller pieces.

Lighting up the totes. Lettuce and kale are in place; I just need to transfer over the basil and swiss chard into the other 2 totes. I taped some reflective white poly to the wall to try and reflect more light back onto the plants.

A pair of Kale sprouts. I ended up thinning them all out to 1 sprout per net cup. The little ones that I chopped were pretty tasty.

I’ll be sure to post progress pictures of this grow and share how the lights perform.

Edit: 05/26/17: Added Reader’s Builds section.

Builds by Readers

Since this post I’ve worked with some readers on some similar builds and have seen some awesome work and new ideas. If you’re looking for more inspiration, check these DIY builds out:

Ted’s 2-Foot LM561C Strip Patio Box Build

This build consists of 24x 2′ strips, all wired in parallel. It’s run off of a Mean Well HLG-480H-24A. This is one of my all-time favourite micro grow setups.

The box.

Scaled diagram of the layout. Ted ended up ditching the fans and will soon be adding deep red and far red stars in their place.

Attachment of the driver to the outside of the box.

This absolute baller got actual heat sinks from

All laid out.

The finished product.

Lane’s 4-Foot LM561C Strip Shelf Build

This build consists of 6x 4′ strips, all wired in series. It’s run off of a Mean Well HLG-185H-C1400.

4' LM561C strips.

4′ LM561C strips.

Another build using real heat sinks for the strips. Nice!

Ozy’s 1-Foot LM561C Strip Build

This light consists of 24x 1′ LM561C strips, and is wired in a combination of series and parallel. It’s powered by a Mean Well HLG-240H-C1750.

Samsung LM561C Strips

Ozymandizz’s DIY QB

DIY Quantum Board

Ichi’s Build Using Rolls of LM561C Diodes

Rather than fixed strips, Ichi bought a couple rolls of LM561Cs, cut them to length, and mounted his custom strips to aluminum channels. 1x Mean Well HLG-185-24 runs all strips at 24V in parallel.

LM561C Strip LED DIY Quantum Board

Rather than using fixed strips, Ichi cut lengths from his reels of LM561C LEDs.

LM561C wired in parallel

The driver is an HLG-185H-24A. All LEDs are run at 24V in parallel.

Wiring on top of the base.

The strips mounted to aluminum channel.

Close-up of strips.

Strips lit up.


  1. Thanks for sharing.

    Which Meanwell driver would you use for a 12 strips setup ?
    How would you wire them ?
    APC-35-700 drivers (two of them) good choice ?

    • LEDGardener

      May 8, 2017 at 7:37 pm

      Hey Barnie. If I were running 12 of the 1 foot strips and they were on some sort of heat sink, I would do an HLG-120H-C1400. I’d wire 4 groups of 3 strips each. The 3 strips in each group would be in parallel with one another, and the 4 groups would be in series. Voltage would be ~23.5V * 4 groups = 94V. Current through each diode would be 155mA, which is 75% of max. You could dim this down as well.

      Each of those APC-35-700 drivers would only really be good for 4 strips. You’d wire 2 groups of 2 strips. The 2 strips in each group would be paralleled, then the 2 groups would wire together in series. Voltage would be ~47V, current through each diode would be ~117mA, or a little over 50% of max rating. You would need 3 of these drivers to run 12 strips – I’d recommend running them with more current like the HLG driver above though.

      • Thanks for your reply.

        Do you see any advantages running 3000k,3500k,4000k and 5000k 4 strips together as one group to cover the spectrum?
        I grow orchids idoor, mainly Phal.


        • LEDGardener

          May 8, 2017 at 9:33 pm

          Oh, neat! A lot of people will argue that spectrum doesnt matter as much as sheer photon output in the photosynthetic range, but recently I’ve read a few threads extolling the virtues of high-CRI LEDs and how different spectrums produced consistently better plants.

          If you have the patience for sorting out all the part numbers for the different colour temperatures on Digikey, I say give it a try!

  2. Great work those look to be very bright, I bet you could spread those out and get a lot more green under them. My first outdoor kratky experiment was with one of those totes, they are a little flimsy but with your bigger net cups your using you should not be filling them up very far as I do with 2″ cups. It should truly be a set it and forget it with enough water for the life of the plants, I get about 2 months of good growth out of lettuce plants before they start getting weird. It’s always a week or so that it all kind of stalls out until the roots get established, but once they get a good root mass going you can chop them back to a center nub and have a new head of lettuce in a week, with 24 plants you’ll have all the greens you can eat.

    • LEDGardener

      May 14, 2017 at 10:47 am

      Thanks Noel! I might be able to get away with 1 strip per 2 cups, but it would be really pushing it I think. I’d have to leave the lights on 16 hours a day probably, which, still, isn’t terrible either.

      These totes have bowed a little bit but they seem to be stable. The net cups do come down a fair bit so the totes aren’t totally full; I have the water level right at the bottom of the net cup so the hydroton can wick some up into the rock wool. I can see true leaves on most of the seedlings now, so yesterday I added my nutrients. PPM is about 400 (and my tap water alone is 200). I’m very eager to see how this works out!

  3. Super nice build. I was worrying about my lack of light on my build. I dont have any quantitive proof but my young plants are growing much better under the Samsung strips than the 3 T5 fixtures.

    • LEDGardener

      May 11, 2017 at 10:30 pm

      Thanks! I bet they like the spectrum better. Still, I can’t imagine you’d have a lack of light with this many diodes being driven over 50%. Do you have a meter to check the voltage of each circuit? Did you wire the entire thing in series?

      • I really think it’s just an illusion. I had 6500k T5’s. I now have 5000k. I’m getting way better light spread. Things seem to be responding better. Seedlings are growing faster. I wired to your diagram for the two shelf module. Positive and neutral leads are split into two then the three strips wired in series.

        • LEDGardener

          May 13, 2017 at 3:56 pm

          See I think that’s your problem – the leads shouldn’t be split in two… You should have the positive go to the positive input on strip 1, and the negative go to the negative input on strip 6, then series every strip in between. My original diagram was for 2′ strips, but as per my last email, if you’re going 4′ strips, it ALL has to be in series. Wire it like this and your lights will be twice as bright!

          Like so

          • Ahh now I see. I forgot about that. I’ll re wire when I get home. Also FYI I started using Advanced Nutrients pH perfect nutes. It is expensive but I never ever have to check or worry about my Kratky pH. I haven’t checked pH on anything in 2 months. I know checking pH isn’t a big deal but I go out of town a lot and when I’m home I work 12+ hr days. It’s just one less thing to worry about.

          • LEDGardener

            May 13, 2017 at 4:11 pm

            Okay right on… I KNEW there had to be something not quite right. You will be impressed with how much light these put out with double the current. A couple weeks ago I actually bought the Advanced Nutrient trio on your recommendation. I’ll have to read up on the pH perfect ones too. Sounds super handy.

          • Now it’s bright!!!! Really really bright. Thanks!!!

          • LEDGardener

            May 14, 2017 at 10:09 am

            Fantastic! Oh, and I looked at the nutes I bought…

    • Now that you have fixed the lights, how hot do the heatsinks get? Any chance you could post your build on the forum for those of us that are looking more into veg growing?

  4. Amazing post and thanks for your help with my LED setup ! great quality photos and writing, thanks!

  5. I modified my rig to follow your wiring:!AqYHuFBsYCyjhIkcAVGIdfo0YN80GQ

    Does this work ?

    Please can you explain why we need to break it down into groups of 4 ?

    • LEDGardener

      May 13, 2017 at 12:39 pm

      Yup, that looks good. We need to break it up into groups of 4 in order to get the right current through each diode with that particular driver. A couple examples:

      If you broke it up into groups of 6, you’d have 1,750mA / 6 strips = 292mA per strip. Each strip has 3 parallel groups of diodes, so that 292 gets split into 3, resulting in 97mA flowing through each group of diodes. 97mA is less than half of the LM561C’s max current, so we want to drive them harder.

      If you broke it into 2 strips per group, you’d have 1750mA / 2 strips = 875mA per strip, then divided by 3 = 291mA per group of diodes and this is over the max those diodes can take so they’d die.

      • Thanks. Just to understand further, 141V according to your post is the voltage across the boards – but the HLG-320H-C1750 is capable of 229V. does this mean we have to somehow set the voltage on the driver ?

        Further to this, how does the dimming work on the driver, does it lower the current ?

        sorry if this is all obvious, I am not very knowledgeable about electronics.

        • LEDGardener

          May 13, 2017 at 2:18 pm

          Since it’s a constant current driver, it will automatically adjust the output voltage to the voltage drop of the circuit, so long as the circuit voltage drop is within the constant current range of the driver. This voltage drop will vary depending on how much current you put through the LEDs and their temperature.

          In this case, our voltage drop is 141V, and the constant current range of that driver is 91V-183V (that 229V you mentioned is actually for the HLG-320H-C1400, not the 1750), so since 141V is between that range, we’re good to go. Have a read through this post for a better overview:

          As for dimming, you’ve got it. It lowers the output current.

  6. Thanks for sharing.I ‘m wondering about spacing and if you think your spacing would be good enough for flowering plants. Can’t get the quantum boards so I thought I would try your build. The quantum boards have 288 diodes on a 6.85 in X 11.25 board & they recommend 2 of these for a 2X4 flowering space, 8 sq ft,576 diodes. Your doing 16 sq ft with 576 diodes. It seems to me if I do your design & cut the space down to 8 sq ft it wold be adequate for flowering plants. In addition it seems to me your design is better because it spreads the diodes out vs the quantum boards and makes heat less of a problem and one could eliminate expensive heat sinks. I would appreciate your thoughts about the spacing and heat sinks,thanks.Tony

    • LEDGardener

      May 24, 2017 at 8:10 pm

      Hey Tony, my build is actually only covering 8 sq. feet, it’s just in a weird configuration. The light fixture is 8 feet long but only 1 foot wide. If you reconfigured the design so that it was 2x 4′ lengths rather than 1x 8′ length, and spaced the strips out evenly instead of staggering them like I did (so they would line up with my net cups), I think you could cover 8 square feet for flowering. Have a look at my buddy ozymandizz’s build here in the user gallery for an example of what I mean. He built his as a square and he’s currently covering a tent that’s about 2.5′ x 2.5′ (6.25 sq ft).

  7. Hey, love the article!

    Could you use the Samsung SMD rolls? Like from alibaba?

    Is there something special about the DigiKey ones?

    Thanks for your help!

  8. Hi ! just a quick question – I want to compare my new rig with my older led (it will clearly win hands down).

    First I am thinking of measuring the watts at the wall of each (using kill-a-watt or similar), so that I can compare light intensity per watt on each.

    To measure light intensity what tool is required ? presumably Id just take a measurement at the same distance below each rig ?

    thanks again!

    • LEDGardener

      May 29, 2017 at 5:02 pm

      The best way to do it is with a meter than can measure PPFD (photosynthetic photon flux density), like an Apogee MQ500/SQ500/SQ502, or Li-Cor LI-190R, or a spectrometer. Unfortunately, none of these options are cheap.

  9. I just ordered (13) SI-B8T11156HUS and am planning to run them all in parallel with a HLG-320H-24A. If I did my math correct, that’s 13340mA / 13 strips = 1026mA per strip. These strips are the 2ft versions of your strips so i believe I’m running them a little harder than you are. Do you think i should invest in 1″ heatsink material or just stick with the aluminum channels? I’m going to run this side by side against another 3×3 tent with a 315w CMH. Cheers!

    • LEDGardener

      May 31, 2017 at 8:07 am

      Hi Danny. The absolute max current for those strips is 1.2A each, which should occur somewhere around 24V or slightly higher (say, 24.2V). 1.2A * 13 strips would be a total draw of 15.6A, which that driver can almost hit (spec says 13.34A, test report says 14.78A), so you’re actually coming pretty close to the upper limit. Since you have an “A” driver (good call) I would adjust the voltage down to ~23.5V to start and see how things go. If you’re running at 24V and these things are pulling close to max current, there’s a chance you’ll have thermal runaway problems in a parallel configuration.

      If you check out this build in the user gallery, you’ll see that another reader used an actual heat sink rather than aluminum channel, which is a great idea if you can get it relatively cheap. If you’re planning on running high power, I’d recommend it.

      • I can get 1″ wide heatsinks from for about $50-60 for the whole build but I think it would be OK to use the channels as I have active cooling in the tent. I already have no heat issues with a 315w cmh so I would assume this fixture would offer even lower thermal load. Thermal runaway could happen with no active cooling right (the room has a mini split AC and I constantly exchange the tent with cool room air). Why is it more likely to have thermal runaway in the parallel config? Lastly…do you still recommend the thermal mounting paste for mounting?

        • LEDGardener

          May 31, 2017 at 9:41 pm

          I’d still recommend the heat sinks if you’re going to drive them hard.

          Whenever you wire in parallel, you’re susceptible to thermal runaway. As a diode heats up, its characteristics change: resistance drops, and an LED with a lower resistance can end up pulling too much current and cooking itself. I’ve done a few experiments with thermal runaway though and found it to be pretty rare.

          I’m sure with active cooling you’ll be fine, but I’d still recommend starting at a lower voltage than 24 and slowly working your way up.

          I’d recommend a thermal adhesive or thermal tape for mounting. Others have used the tape without issue.

          • Ok, I’ll look into using heatsinks instead of channel bar. Do you have a recommendation for a thermal adhesive or tape?

          • LEDGardener

            June 8, 2017 at 10:39 am

            This is what I used and I can attest it works very well: 10g Thermal Conductive Plaster Viscous Adhesive Glue for PC Heatsink GPU IC Chip LED Ovens I used 5 tubes for 24 strips. If you go the tape route, just make sure you get the right width. I would have preferred to use tape but it was way too expensive to get to Canada.

  10. So, in your opinion (for flowering) should I go with this setup or 4 CREE CXB?

    • LEDGardener

      June 1, 2017 at 1:05 pm

      If you’re in the states, I’d just order a real QB. It’s cheaper than DIY and way less hassle. If you aren’t in the states, it’s a toss-up. I have a 4x CXB light too, and it performs really well. I’d say it was easier to assemble the CXB lights than the strips, but the more even coverage and better efficacy of the strips are big benefits. If you’re looking for simplicity, go Cree. If you’re looking for performance and flexibility and don’t mind putting in the work, go with the strips.

      • Problem is you can’t buy the QB unless you get lucky :(. My order from arrived next day can’t beat that!

  11. Hey man thanks for all the great info and effort, you cleared a lot of doubts i had about those strips…I have a bit of a problems with a calc, just can’t get the numbers to match so if you can help out with my design and tell me if it’s gonna work or give an advice what to change i would appreciate it…so here is my plan
    I have hlg 240 1750…i also have 4 cxbs i used with that driver but now i want to include some strips too…here is my plan so if you can tell me if i got something wrong i would appreciate it…2 sets of 2 cxbs on parallel, each one at 875ma…that leaves me with around 71-72v for the strips…so i was thinking adding 3 sets of 3 parallel 2.5 feet strips each counting 48 diodes but i just can’t seem to get the numbers right on the calc…does my build makes any sense to you or am i doing something wrong?Appreciate any input or advice you could give me

    • LEDGardener

      June 11, 2017 at 4:41 pm

      Hey there. I’m mobile right now but off the top of my head your plan looks fine. Your math is good for the COBs. If you go 3 sets of 3 parallel strips, that’d be 1750/3 strips = 583mA per strip. 583/6 strings of diodes per strip = 97mA per diode, or just under 50% of max. That’s probably the softest I would run those – I drive mine at about 150mA (75% of max) each.

      • Thanks for the confirmation.Yeah i want to run them soft so i can keep the fixture at 10-12″ above canopy cause i’m having a bit of height problem.I can also go for 3 sets of 2 parallel and run them harder if you think that would be better.Will the same math apply if i use the flex strip which has 6 diodes in series instead of 8?Not sure which will be available to me in low moq on alibaba and if i’ll be able to get the 90CRi
        Sorry about not posting in the forum i saw it just after i already posted here

        • LEDGardener

          June 11, 2017 at 7:49 pm

          Right – if you’re that close to the plants, 100mA will be more than adequate. Can you link me to the other strips you’re thinking of?

          No sweat about the forum – I actually changed that sentence after you had posted already.

  12. Great article. How did you get the max current number of 450mA? The datasheet says 240mA for the 1 foot units.

    • LEDGardener

      June 27, 2017 at 6:30 am

      Thanks EJM. The max current is 200mA per diode sqo I worked backwards from here. That makes the max current per strip 600mA – that 450mA isn’t a maximum.

      • Thats a bummer, as I bought a 450mA driver to push one of the 2 foot units based on the datasheet saying 450 mA for the 2 foot unit. I guess, looking at the data sheet you do that based on 3parallel strips * 200mA? Does that mean I could drive the 2 foot unit with 6 * 200mA = 1.2 amps?

        Can you give me some noob advice about how to think about the rating/operating current on the datasheet vs deriving the number the way you did? This is my first time making a light.

        • I just finished wiring The 2 foot strips. They are 24.2 V and 1200 mA in the 4000 Kelvin temperature. I am driving six of them in series off an hlg-185h-c1050 so 1050ma driver. It can handle up to 8 strips at full power.

        • LEDGardener

          June 27, 2017 at 4:12 pm

          You’ve got it now – that 450mA was just the current they did all the other testing at. I just went to the LM561C data sheet, found the absolute max current per diode on that sheet, then applied that to the strips.

          Max current for 1′ strip = 200mA * 3 parallel groups = 600mA
          Max current for 2′ strip = 200mA * 6 parallel groups = 1200mA
          Max current for 4′ strip = 200mA * 12 parallel groups = 2400mA

  13. hugging-tree-smoker

    July 15, 2017 at 2:13 am

    Hi ledgardener!

    Your blog and articles are amazing. Excited by this article I ordered some SPMWHT541ML5XAUMS6 ( to make a passiv micro-quantum board for a spacebucket (270x270mm aluminum plate). Because they are on a roll I’d say they are wired in series.
    But I have no experience and the forward voltage is a bit confusing. I hope you can help.
    If I run them of a HLG-240H-24A should I cut 9 diodes in series and parallel them together so they get slightly underdriven or cut 8 diodes in series and parallel them together but dimm the driver to 22V?
    I just go of the forward voltage of up to 2,75V.

    Thanks for your help

    • LEDGardener

      July 18, 2017 at 11:04 pm

      Hey buddy, sorry for the delayed response on this. I would wire 8 of them in series and then parallel these strings together. This is how the pre-made Samsung strips are wired. If you run the diodes at half power, you can expect a voltage closer to 3V per diode (the Samsung calculator says you should get 2.92V at 100mA of current). If you’re getting 2.9V, 8 of these would give you a total voltage drop of 23.2V.

      Whatever you do, make sure you drop your voltage right down before connecting the diodes, then REALLY slowly increase it. That voltage will jump really quickly with hardly any adjustment. Put a multimeter on the circuit and take it up to 23V and see if that’s bright enough for ya.

      • hugging-tree-smoker

        July 19, 2017 at 10:22 am

        No worries about any delay. There’s still stuff missing before I can even start building.

        Thanks for the detailed response. If everything goes well, I will add to your user gallery and create a reddit-diy-post.


        • LEDGardener

          July 19, 2017 at 10:25 am

          Right on man. Since my little forum is now up and running, I’m trying to consolidate all of the cool builds people share over there. Please make a thread in the forum to share your pics!

          • hugging-tree-smoker

            July 22, 2017 at 3:36 am

            just for you to have a laugh:
            My hopes and dreams regarding selfmade quantum boards are crushed by reality. I recieved 250 individual LEDs and will probably send them back. I am not that kind of a solder-masochist (hell, they are tiny). Still got a vero 18 I will setup now 😀

          • LEDGardener

            July 22, 2017 at 8:31 am

            You know, I was seriously contemplating asking you if they came connected together in any way on that roll or not, but didn’t want to risk sounding like a dumb-dumb. We all learned something today! Thanks for sharing and good luck with the Vero. I have a couple of those 18s in space buckets myself.

  14. If i wanted to run 12 1footers what drive would run them 100% with dim if needed

    • LEDGardener

      September 2, 2017 at 8:18 pm

      The easiest way to do that would be to grab an HLG-185H-24A and run them all in parallel. That would be a great match for 12 strips.

  15. Hey Led Gardner, quick question. i was wondering how to split up “LT-M562C_G2” version of the strips.
    i was thinking of getting 24 of them and splitting them in groups of two to have a total of 12 . Whats the best option for a driver? Appreciate the help ~!

    • Hi Roberto, any reason in particular you’re looking at the 561B+ strips rather than the LM561C? You could run parallel and use 2x HLG-185H-24A (1 driver for each group of 12), or you could run them all in parallel of of an HLG-320H-24A. You’d want to be sure you grab the “A” version of the driver because these strips run a little higher voltage than the LM561C so you need to be able to adjust it higher to get the same current through them.

      When you run parallel on these strips, I’d recommend against using the built-in connectors on the strip, and use your own connectors (Wagos or similar) to make each splice. The board connectors drop a lot of voltage and you’ll end up with dimmer lights at the end of your run. Check out this thread in the forum for more info:

  16. Hey Ledgardener,

    would it be a bad idea to wire such a build just in Series?
    I´m planing to light out a 1,44m² tent with FB22B.
    The plan would be 18x FB22B (since they have 144 leds each and are 1120mm long they seem perfect for a 1,2mx1,2xm tent) running at 700mA.

    From my research they would need 794,88V in total which would be great with 2x HLG-320H since the driver can handle 428V at 700mA. The setup would run at 550Watts, 59,5% efficiency and 1104 PPFD.

    I will post a thread on the forum, just wanted to check with you first what you think about that setup.

    Thanks and have a good day.

    • LEDGardener

      October 12, 2017 at 9:48 pm

      Hey Andi, the main problem with running this many in series is the voltage. Having almost 400V on a single run is pretty dangerous and also exceeds the safety ratings for the connectors on those strips. You could certainly run these in series if you broke them up into multiple smaller drivers though.

      • Alright thanks for your reply. Would you mind giving me an example for a driver with wich i could parallel wire 9x strips. I only worked with series wiring before and am kinda confused on which driver to choose.
        From what I understand if Id want 9 stripes on 700mA each i need 6.3 amp driver.
        Maybe something like the HLG-150H-24. Just confused since it says max 150Watt on the driver, I guess it has to less V?


        • LEDGardener

          October 13, 2017 at 9:33 am

          Have you seen the calculator in the latest post?

          • Yea I looked at it, just didn´t quite get the “HOW HARD WILL YOU DRIVE YOUR STRIPS?” since it´s 25% steps. On a Grow forum there has been an excel sheet rlsed to that topic, I was planing my build after it: . That´s what I planed to run on 1 driver(700mA to have a total of ~550W whenh running 18 on 2x 700mA). But it seems the 50% drive from your calculator seems fine as well, guess I could just run them the following and dimm it down a bit:

            I´ll do some reading on how to power them up later tonight and post a thread on the forum than, don´t want to bother you too much with this.


          • LEDGardener

            October 13, 2017 at 5:41 pm

            Ah, yeah those percentages are based off of the max current the strips can take. The LT-FB22B has an absolute max of 1800mA, so driving at 50% of max would be a current of 900mA. If you wanted to run at 700mA, that’d be .7*18 = 12.6A and remember, these aren’t 24V strips, they are 48V (well, they’ll run at a slightly lower voltage at this current).

            That being said, you could run all 18 on an HLG-600H-48, or you could split it up and run 2 groups of 9 strips on 2x HLG-320H-48.

  17. James McWhorter Jr

    October 13, 2017 at 3:00 pm

    First thanks for doing the hard part for us, now my question is about the aluminum. I have access to 4 5/8 wide 1/8 thick c channel in any length I want. Would this be sufficient for these strips. I’m thinking 4 strips across. I’m I a 3ft x 1.5ft space. I ordered 24 PCS. Thanks in advance

  18. Hi! The build looks great. I’ve read through about a hundred times and I’m struggling to figure out what driver I’ll need.

    I’ve just got 8 of the foot long strips. So will either wire them in 2 groups of 4 or 4 of 2.

    How would you recommend I do this, I’m no electrician!

    Help would be greatly appreciated!

    • LEDGardener

      November 8, 2017 at 9:37 am

      Hey Curt. Easiest way to do this would be to grab an HLG-80H-24 and wire them all up in parallel. This’ll run your strips up to 70% of max, which is great, and you can always dim it down too.

  19. Thanks, very useful to see several different builds. I am planning to use (6) 4′ Samsung HB22 strips in series just like one of the examples shown above, but am confused about the current requirements.

    Datasheet says Operating Current = 960mA but the build on this page is using the 1400mA Mean Well driver, so clearly these boards can take more than 960mA.

    I don’t see a max operating current parameter on the datasheet, so how do we determine the optimum current to drive them with? I will also add a potentiometer on the driver to be able to lower the output when desired.

    Also how do we convert this output to PAR to know our actual light output? Thanks again for a super useful site.

    • LEDGardener

      November 8, 2017 at 11:50 pm

      Hey Joe, the 960mA in the data sheet is just the current that they happened to take their test measurements at. We can derive the true max current for these strips by figuring out how the strip is laid out and then referencing Samsung’s data sheet for an individual LM561C diode.

      According to the data sheet, the LT-HB22D is made up of 12 parallel runs of 8 diodes in series. This means that we can take the absolute max current of a single LM561C and multiply it by 12 to find the max for the strip. The LM561C data sheet indicates that the max for a single LM561C is 200mA, and 200mA * 12 parallel runs = 2.4A max for the strip. You’ll probably want to run it somewhere from 50% to 75% of this max.

      Unfortunately, there isn’t really an easy way to convert lumens to PPF or PPFD.

  20. Hello! I want to put 12 strips, 56cm, to a HLG-185 700A and want to run them at 500 – 700mA, so to ~185w. Could you please tell me how exactly I need to wire them? I dont really get it with serial and paralels, when I need to do what, maybe cause my english skills are too bad, and I am worried to do something wrong… So could you maybe show me a picture or something?
    Thanks in advance for your help. 🙂

  21. Thank you for this. It is exactly what I was looking for to replace my T5HO fixtures.
    Here’s my idea: to use B8R05128HUS (5000K) and B8T05128HUS (4000K) as 4 strips is series on an 4 foot aluminium bar that matches the T5 54W length, in a 5K-4K-5K-4K, alternate with 4K-5K-4K-5K and so on for a nice mixture (I hate the yellowish light on plants but I know they need the red portion of that and the 5000K might make it look better, although more expensive). Can these 4 strips be connected in series and if so, what do you recommend, a constant current or constant voltage? I did 3W led assemblies before and it was simple with the voltage drop from the constant current driver, but I seem to be staring in blank at these strips. I would actually need 4 of these bars to exactly match the T5HO fixture, so is a single driver OK, and if so, which?
    What is your opinion regarding the 26W T5s (3900 lm) that Philips is selling now? I already have those and they do seem very bright and the plants respond well, but to add another shelf would mean buying another fixture and then the replacement LED bulbs which would double the price (30 euro a piece means a steep 280 euro for the whole thing). That is why I am trying to pick some ideas, perhaps the LM561C option would be a (slightly) cheaper alternative.

    Thanks for any information you might share!

  22. Hi,

    Did you attempt to take temp measurements (before and after) in order to quantify the effectiveness of you U channel heat sinks?

    • LEDGardener

      December 12, 2017 at 1:55 pm

      Unfortunately I didn’t have my thermometer at the time so I did not get any measurements without the sinks. I saw a Gromau5 video where he checked some EB strips without sinks though and the small ones running at higher power got way too hot.

      • Cool, thanks for the reply. I’ll try and look for his video.
        I’ve got some 40mm wide x 415mm long strips coming… I’m just trying to gauge whether I can get away with mounting them to 1.75″ or 2″ wide 1/8 or 1/16 thick aluminum flat bar.

  23. Hey, me again. I see that no reply was given earlier, so I researched and found this easier (for me, at least) solution. I would really appreciate your input regarding the Vf-mA match: LT-QB22A 5000K 1120 mm board, each with a PLD-25-350 driver. I mention that these will be used for orchids, so only 4 pieces/shelf. I basically need not more than 18000 lm/ 120 x 50 (or 60) cm shelf, so will these drivers give me the desired output? Thank you!

    • LEDGardener

      December 18, 2017 at 11:50 pm

      Hey, sorry that other comment slipped through the cracks. If you want to run them all in series, for 4 of the 1120mm strips, an HLG-120H-C700 would fit the bill. If you wanted to run parallel, a good match would be an HLG-100H-48. Either of these methods will work nicely and will allow you to dim all 4 strips simultaneously.

      I’m trying to consolidate all questions like this in the forum so that they’re all in one place and there’s a better chance other people can benefit from them too – if you’re looking for more info, if you could please make a thread in the mid-power section of the forum, I would be much obliged!

  24. Great write-up, and SUPER helpful as I plan out my own build. Quick question… If I plan on using half the LED strips (12 total), and would like to follow your wiring instructions to the letter (I’m an avid DIY guy, but never wired something this complex), can I use a smaller (less expensive) driver? And if so, do you have a good recommend?

    • LEDGardener

      January 3, 2018 at 7:32 pm

      For sure. Will you use the same 1 footers? There’s a newer series called the Samsung F series of strips that packs more diodes in and doesn’t cost much more.

      • I was planning to use the same 1ft’ers, simply because of this post. I’ve been using a DIY CFL rig I made, and would like to move to LEDs. This post is a great “recipe” to follow, but I’m kind of a noob without much knowledge when it comes to LEDs. My tent is about 24x36x60, and I was thinking of cutting your 8ft rig in half, and squishing the strips a little closer together.

        What would you recommend for the F series, keeping it at 12″ strips?

      • I did some searching on Digikey and found the F-series you referenced. I was curious what you thought about using the 1 meter long F-series strips? Going by Digikeys specs, a single 1-meter strip puts out 8800 lm, while 3 of the SI-B8T05128HUS would put out roughly 3000 lm (I know this isn’t real world figures, but I’m just comparing apples to apples for comparison sake).

        So I’m now thinking that running two of the 1-meter F-series strips (roughly 18000 lm for about $50.00) would be more efficient/less cost than running 12 of the 1 ft. strips (roughly 12000 lm for about $120.00).

        If you agree, could you suggest a good driver for this setup?

        Link to the 1 meter strip:

        • LEDGardener

          January 7, 2018 at 5:24 pm

          For those ones in particular, to run 2 of them, an HLG-120H-C1400 would be a nice fit. That’d run them at about 75%. If you’re going with the 4 footers, you can get 2 types – the FB22B which you have linked or the FB24B which has twice the number of diodes on the same strip. If you went with the FB24B, to run a pair, you would need an HLG-240H-C2100.

          • Awesome, thanks for the advice. So to make sure I have this right, I’m grabbing 2 SI-B8U521B20WW’s and a HLG-120H-C1400. When you say to run it at 75%, I’m assuming you mean to put it on a PWM dimmer? Since this is my first build, does that dimmer go between the driver and lights? Or between the driver and power source?

          • LEDGardener

            January 22, 2018 at 7:54 pm

            Yup. Parts list is good. You don’t need to PWM with the HLGs. You can get either the HLG-120H-C1400A (comes with built-in dimming on the driver and dims from 100% to 50%) or the HLG-120H-C1400B (comes with dimmer leads so you can solder your own potentiometer to it and dims 100% to 10%).

  25. I was thinking of grabbing 6 of these and wiring of 2 lights with 3 SI-B8VZ91B20WW each. Can you recommend a driver? Are these the most efficient led strips out atm?

    • LEDGardener

      January 8, 2018 at 6:37 am

      Hey C.C. The most efficient strips are the Samsung W series with LM301B diodes. If you’d like some help with design, please make a thread in the forum.

    • I cant find the Samsung W series with LM301B diodes you speak of but what are your thoughts on the f series SI-B8VZ91B20WW. I was thinking 4 of them in parrellel on a 709-HLG-480H-48A
      would give best efficiency low heat and plenty of room to upgrade need be. Any thoughts my man. Thanks again

      ps are you that guy on youtube the ledgardener? great videos id love to see more about these light stroips i think in a years time everyone will have picked these over all other options.

  26. Hi, total newbie into grow lights. Have been following you for some time. Great work and very informative.
    Would benefit with some advice on my planned build. I plan to setup a 6′ L * 6′ H * 2′ W enclosed Aluminium box (have this already, will provide 3 fans in the top for active ventilation) for growing vegetables indoors. My plan is to have 6 vegetable beds at 1 ft height apart and provide grow lights from the front (6′ * 6′). The front is a split door, so this turns out to be 2 doors of 6′ * 3′ each into which I will attach the lights. Since the vegetable bed will be only about 18″ from the front, I am a bit concerned if the plants can get too close to the light source as they grow and light distribution taking a hit or plants getting burnt from the heat as they grow taller. I think COBs is a bad idea for my need due to their intensity at source, so LED strips / Quantum board make more sense. But even then, is this a terrible idea? Any suggestions?

    • Sounds like you want to do very close to what I am in the process of building, see forum post here: Its kind of hard to visualize what you have planned but it sounds like you will be providing light from the side (?) which will make things unnecessarily complicated.

      The type of density you describe (veg beds 1′ height apart) is only possible if you grow very short plants (~6″) on thin floating rafts or nft channels. Think of it this way, you need growing container & media (2-6″ min) + plant height (6-8″) + min. light distance at max plant height (6-12″) + light frame & hanging hardware (2-6″). This puts you at about 16 – 32″ depending on your setup, add in 0.5″ for shelf thickness and +6″ if you want to grow anything that’s ~12″ tall.

      Beyond that, its going to be a pain in the ass to inspect, maintain, and harvest your crops if you are fighting to see and manipulate plants when there is only 6″ of open air between each shelf. IMO you should do aim for 2′ MINIMUM and enjoy greater flexibility and being able to actually see what you are growing.

      • Yup, very similar approach I think. But dang… Really wanted to grow the plants 1 ft apart (each rail will be offset from the other by a minimum 6 inch like a step pattern, so height available for growth will be a minimum of 2 ft for any plant. There were some other advantages that I saw with such a step like configuration, but I am afraid I will not be able to get even 12 inch minimum distance to the plants from the lights once they grow. Going back to the drawing board again 🙁 Thumbs up to your design though and it gave me some new ideas as well.

  27. does samsung make those strips in 3500k

  28. Hi, so I can wire twelve 24 diode strips (288 diodes total) in series with HLG-120H-54A and it draws about 120w of power, im I right? Im planning to use that flexible tapestrip so less soldering and wires are best option for me.

  29. Hey LED Gardener,

    Thanks for all the great info on your site! I am a little jealous that you got kale growing in rockwool, I’ve tried that several times without much success (where other plants grew fine alongside). Was wondering if you had any special tricks for kale?


    • LEDGardener

      February 22, 2018 at 10:58 pm

      That’s interesting – I didn’t have any issue with it and treated the kale just like the other stuff. Did you pH the water you soaked your RW in?

      • Yeah I used ph’d water. They sprouted and then stayed sad little spindly seedlings and didn’t thrive. Thanks for the reply, I probably did something wrong without realizing it. I’ll try again!

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