Power LED Shield V2

Reposting this here as I had originally posted in the wrong forum.

I’m almost done with Power LED Shield V2. Here are some of the key specs:

  • 4 channels at up to 38 Watts each (152 Watts total output power!)
  • Driver modules available in 300, 350, 500, 700, 1000 and 1200 mA capacities
  • Up to 10 LEDs in series per channel (more if you run them in parallel)
  • Dimming selectable between PWM, Analog or BOTH, plus manual analog dimming adjustment on each channel
  • Each channel driven from any of the Arduino PWM pins - jumper selectable
  • Compatible with Duemilanove and Uno, possibly the MEGA boards too (I don’t have a MEGA to test on)
  • Input: 6-36 VDC @ up to 5A

The Power LED Shield V1 thread from the old forums:

My flagship application of V1 happened in the reef aquarium community:

More information at:

I’ve been through several redesigns to get the features I wanted in this version, which has taken a long time. I’m targeting sending it out for manufacturing this month and should have them available in March.



I am very interested in your solution. I would like to know which settings to use to 30W with a 12v battery.


There are many ways to accomplish 30W output at 12V. I need more information on your project to give you proper guidance on how to connect everything. Please provide a description of your project and any details about how you intend to build it. From there I can ask you for more specific details.


I'm trying to follow the schematics of your Power-LED shield V1.6 schematics.
The only thing that I don't quite get is the arrangement of the 220 uF capacitors.
Should they be connected in parallel like you show on the diagram or do I need to connect each capacitor between the exit port of each BuckPuck???

As I interpret from the schematics and from your note at the bottom of the diagram, each LED should be connected in Parallel with ONE capacitor and the parallel connected between Vin+ and Vin - and between the output terminals of the BuckPuck. Is this right???

T1 ---------------
220 uF LED
T2 ---------------

And so on for the other 3 channels...

Thanks for the kind reply,


Hello again! :slight_smile:

The 220 uF capacitors are for the power input of the BuckPucks. They do not connect to the LEDs.

Ugg. After reviewing the schematic, I can see why you are confused. I accidentally used the labels "T1" and "T2" on two different parts. (Let's call this another reason for making the V2 board.) The T1/T2 connected to the capacitors on the top left are for the power input - they do not connect to the LEDs. The T1/T2 connected to the LEDs on the right side are for the first LED channel. They should be connected to the LEDs, NOT the power input.

Sorry for the confusion!

Hi Koyaanisqatsi, I have in mind to develop a 30W lamp with LEDs Cree. I have a battery varies from 11.75 v and 13v. Using the UNO Arduino control the light intensity (PWM) as the level of battery charge (the less load less light). Being an autonomous system energy efficiency is important. I would like to limit the maximum current for the diodes do not burn. Could I serve your plate? How should I connect the LED and DC / DC you need?


For a lamp, it will be easy to connect the LEDs. You will need multiple drivers to get 30W.

I suggest using Cree XP-G LEDs as they have a very high brightness per watt rating, and can handle high current. The drivers on the Power LED Shield V2 can deliver 1200mA per channel (there are 4 channels), which will run the LEDs very bright!

Here are two options:
a. 3 drivers and 3 LEDs per driver. That will give you about 37W across 9 LEDs. You’ll have more light, but little ability to track the battery voltage.
b. 4 drivers and 2 LEDs per driver. That will give you about 33W across 8 LEDs. This will give slightly less light, but much better ability to track the voltage of the battery.

The drivers regulate the LED current. And, since the LEDs can handle more than the drivers can deliver, you don’t have to worry about burning the LEDs out. However, you DO have to make sure the LEDs remain cool during operation. Their lives depend on staying cool, especially when being driven at 1200mA.


Dear koyaanisqatsi,

thanks for the find reply! I realized what was the right placement for the capacitor looking at the datasheet of the BuckPuck.
I'm looking forward to see the schematics of the V2 of your shield.

Do you have any suggestion or advices to give me regarding the use of a LM317 regulator for driving power LED!?
Is there a way to use this regulator in combination with PWM?
What is the main advantage of your solution with respect the use of these cheep regulators?

Indeed and once again many compliments for your success!


Hello rikseventyseven,

I appreciate your compliments!

I have used the LM317 as a driver for power LEDs. It makes a very good low-cost constant current source. However, since it is a linear regulator, it has to burn off all the extra energy as heat. So a heat sink is usually needed.

You can use PWM to control brightness on this type of driver using a MOSFET as a switch. I have not tried using a MOSFET and LM317 together like this, so I can't say how well it will perform.

And here is a chart of values for R1

The biggest difference between the LM317 driver and the drivers on my Power LED Shield is the LM317 is a "linear" driver and the Power LED Shield uses "switch mode" drivers. Switch mode drivers are more energy efficient and run much cooler, so they rarely require heat sinks. If your project requires energy efficiency, you certainly need to use switch mode drivers. Linear drivers generate a lot of heat, so that has to be managed properly with a suitable heat sink.

EDIT: the schematic shows only one LED, but any number of LEDs can be used, up to V+ minus about 3V.


Hi Koyaanisqatsi,

I just registered with the intention of getting your expert advice and hopefully my hands on some of your LED shields. I was attempting to reverse engineer your V1 design (since it is no longer for sale), then I ran across this site several days later - ugh! I didnt realize that V2 was even in the works, but luckily I found out before ordering 6 Buckpucks from LEDsupply. I was literally 1 click away from check out... Anyway, I’m building a hood for my REEF aquarium (45 Gallon Pentagon), and was thinking I’d be running 36 LEDs (this being based off of the 6 max LED config using the LuxDrive buckpucks):

12 CREE XP-E Royal Blue

I can provide more detailed specs/possibly BINs of the LEDs if you like; off the top of my head I think the XP-G’s use 1000mA, whereas the Blues & Royal Blues use 700mA for “peak” efficiency. With your new version 2, will I only need 1 of your Shields (before I was thinking 2 since I would have needed 6 Bucks)? Could probabably run up to 40 Leds w/ V2 on a single shield, no? I have so many questions, but I'll save those for later. Hopefully you don't mind. What I want to know most right now is when do you plan on having them ready for sale? I will definitely buy!

Thanks in advance for your response – J

One thing I forgot to ask - is V2 going to work with the dangerduino/Krusduino project? Thanks again!

Hello again! :slight_smile:

Yes, the V2 shield will work with Krusduino - in fact I specifically made sure of it this time. With the V1 shield, I released it with some limitations and then learned about Krusduino later, to find out the limitations I accepted were in direct conflict with Krusduino. I'm not making that mistake twice. :wink:

The V2 shield can drive up to 10 LEDs per channel with a 36V power supply. At 24V, you can drive 6 or 7 LEDs on each channel, depending on the LED specs.

I should have the V2 shield available toward the end of May. I've had some delays, but I'm pushing to get it out asap.


Thanks for your quick reply Mark, both to my posts and the emails I sent! I'm responding to your post so maybe others can benefit from our dialogue (but I will gladly do email if you prefer). I think I read in another thread that you were switching from the LuxDrives to the Recom drivers. (FYI: I saw them priced quite well at Digi-Key, much better than FutureElectronics). I also like the prices at Jameco for Power Supplies. Wasn't sure if you were aware of these sites (I've used Digi-Key and Jameco several times to purchase various components for SUMO bots and have been very pleased with their rock bottom prices, customer service, and speedy delivery time). Digi-Key, btw, will give you a pretty nice price break at 25 units. Hopefully you will be making at least that many! Oh, are you planning on selling the V2 as a kit (where whoever you sell it to installs the components & buys the drivers seperately), or are you selling them made to order fully assembled?

At any rate, with this new shield, I'm now thinking I will have the following configuration:

20 CREE XP-G R5 WHT-L1 (Channels 1 & 2)
20 CREE XP-E Royal Blue (Channels 3 & 4) or 10 XP-E Royals (CH 3) & 10 XP-E BLU-L1 (CH 4)

As a 2nd option (not sure yet), I might do an additional 6-10 CREE XP-E BLU-L1 for the Lunar Cycle and stick with the 20 WHT:20 RoyBLU ratio for the daytime lights (maybe a little overkill for a 44 gallon pentagon?). If I go this route, I will most likely need a second shield. So if I decide to go this route, two shields (total of 5 channels), will one 36V Power Supply still be enough for both shields, or is another PS required? For the first configuration, what Amps should the PS be rated to handle the Arduino, up to those 40 LEDS, up to 3 fans, and leave some overhead for possibly an automatic feeder (thinking of gutting my Eheim 3581 feeder that runs on 2 AA batteries and having the arduino control the feeding times)? The fans will most likely be hooked up to a temperature sensor. And for option 2, what Amperage should the PS be rated to run all that and up to 50 LEDS (assuming that 1 PS can run two shields simultaneously)? Either way, I plan on buying two of your V2 shields for future upgradeability and the fact that you will most likely sell out of these puppies quick, leaving another long wait until V3 arrives! XD

Anyway, sorry for the long winded responses and questions. Thank you so much Mark!

Oh wow Mark,

I shoulda asked about the specs on the new version in the emails.....10 LED's per channel....am gonna need it now for sure...lol

Hello again! :slight_smile:

Yes, the V2 shield will work with Krusduino - in fact I specifically made sure of it this time. With the V1 shield, I released it with some limitations and then learned about Krusduino later, to find out the limitations I accepted were in direct conflict with Krusduino. I'm not making that mistake twice. :wink:

The V2 shield can drive up to 10 LEDs per channel with a 36V power supply. At 24V, you can drive 6 or 7 LEDs on each channel, depending on the LED specs.

I should have the V2 shield available toward the end of May. I've had some delays, but I'm pushing to get it out asap.


I haven't' decided yet if I will officially offer the new board as a kit. Kits tend to require a huge amount of time for support and can be very frustrating to the customer if theirs doesn't work. Also I can thoroughly test each board if I build them or have them manufactured. On the other hand, kits sell very well because they are less expensive than the complete boards. So I am still undecided. If you are well-skilled at soldering and building circuit boards, I could be persuaded to sell you a kit. :wink:

I'd like to clarify one point about the output specs: I previously stated the new drivers can run up to 10 LEDs per channel. This is a misleading statement, as I have discovered reading into the spec sheet further. The maximum output is actually 33V, which can only drive 10 LEDs if the LEDs are rated 3.3V or less at the desired current level. Many white, blue and green LEDs are rated as high as 3.6V in the 1000-1200mA range, so you could only run 9 of those per channel. I've changed the info where possible to show 33V output rather than "up to 10 LEDs".

Status: I've completed the circuit design and board layout. I'm in the validation/burn-in phase, which is when I build the entire board and push it to the limits to make sure it stands up to spec. Most of the time all goes well, but sometimes there is smoke and fire, at which point I have to circle back and fix the issue. :wink: This is a pretty straight forward circuit though, so I do not expect any troubles with the burn-in. Once burn-in is complete, the design goes out to manufacturing and I haggle, leverage and schmooze my vendors for the best pricing on parts.

Thanks for the vendor tips. I'm stoked to see Jameco has such a broad range of supplies. The others don't seem to carry many 36V supplies. I'm compiling a FAQ with links to resources and this will be a great addition to that.

On power supplies, with 5 channels fully populated, you'll need 250-300W (or more) at 36V. (each shield needs a 200W supply when fully populated) You could use a separate supply for each shield, which I sometimes suggest, especially when there are several shields. It just makes wiring a little easier to work with because you can use thinner supply wires. The fans are usually 12V, so three in series will run on a 36V supply. Or you can get a separate 12V supply for fans and other stuff. I also make a shield with fan, temperature and clock on it for reef tanks.

For moon lights, there are a few ways you can go with that. Some people use the daylight blue LEDs, but at their lowest brightness value, which seems to work well and saves some hardware cost. Also, you can use regular 5mm LEDs. If you're up for it, I have a circuit that allows for the moon to traverse the sky instead of just sitting still. It's from another project I'm working on for a paludarium. 8)

Power LED Shield V2 is now available at Chester's Garage!


I'm still working on documentation and it should be available in the next few days.

The shield is available with a variety of driver sizes, ranging from 350mA to 1200mA, or without drivers if you want to install your own selection. Any combination of driver sizes is supported.

I'm planning a project to modify my floor lamp to use RGB LEDs. I'm using this lamp:

For this project, I'm considering using the Power LED Shield to power one, preferably two of these RGB LED plates:

The green and blue channel require at least 32V, so it seems I need to find a 32V power supply. Unfortunately, I only need three channels, one for each color, so I'm not sure what to do with the four channel. Maybe I'll use it to power a white LED assembly.

Will I be able to power two of these RGB plates with one shield? If not, can two stacked shield share the same power supply?

For 32V, I think I can't use a laptop DC adapter as those supply only 24V. Any recommendations for those?

One of the many good things about the V2 is you don't have to fully populate the shield in order for it to work. You can have 1, 2, 3 OR 4 per shield. So really, you don't have to use all 4 channels, but it's there in case you want to. You could in fact use the 4th channel for a cooling fan, and use a temp sensor such as the DS18B20 to monitor you LED's temperture to control the fan via PWM through your Arduino. That's what I would do, use Channels 1-3 for the LEDs, and Channel 4 for the fan.

This is the power supply I used with the V2's:

The V2 uses RECOM drivers, so it will accept Power Supplies up to 36V. Many more PSUs that fit your needs are available at http://wattsupply.com/s.nl/sc.30/category.2200/.f

Both of these sites you will have a hard time beating their selection, price, and service. Enjoy!

I can't guarantee the Power LED Shield will drive those LEDs. The site is light on spec data, but the info posted by others suggests they could work. The Power LED Shield can handle up to 36V input voltage and can deliver up to 33V to the LEDs. As long as you don't get one that needs more than 33V on any of the colors, you should be OK. But it will be close. The 36V supply linked by TheDOdblG would work well.

You can't (at least you shouldn't) drive something like a fan with the LED drivers. They are constant current drivers and will push as much voltage as necessary to achieve the desired current. Fans and most other electrical devices require a specific voltage and will draw as much current as necessary to do what they need. LEDs are "different" in that they require a constant current value at whatever voltage is necessary to obtain the current. This is why LEDs are sometimes rated with a range of voltage rather than a specific voltage.

I have another product coming soon that controls fans and has the DS18B20 and a real time clock too. It's for aquarium and similar projects.

You can order the Power LED Shield with any combination or number of driver modules. My site doesn't show it because it would be a zillion different options. But email/PM me if you want to order a board with a custom selection of drivers.

I'm really happy to see that link to wattsupply.com. I have had a hard time finding sources of 36V supplies. They seemed so common when I started designing the V2 board. But once I released it, I couldn't find the 36V supplies as easily!


Are there limits to how far away the LEDs can be from the Power LED Shield? (I seem to recall that a BuckPuck wants the LED to be 6" away max.)