Go Down

Topic: Power LED shield (Read 21467 times) previous topic - next topic


OK, they're in and I've built and tested the first one!  It works without any mods - w00t!  (pics/vids coming soon).  

I ordered a bunch of PC boards and a couple sets of parts for kits.  I'm still trying to get my store running, but if you would like to buy them now, PM me and I'll give you my paypal account info and the prices.  I'm selling them to the first 10 Arduino Forum folks who PM me for cheaper than in my store.  Call now and receive free Ginsu knives!  Wait...  wrong commercial.

I currently have:
o lots of bare pcbs - buy 2 or three!
o two kits, will order more soon - NOTE: the kits do not come with the *Pucks because I can't get a good price on them for resale.  Buy them at ledsupply.com or wherever you can find them.
o zero complete boards other than my demo.  If you would like me to build yours, please PM me.  Any combination of up to four Buck/BoostPucks can be on one board.

Anything I run out of, I'll re-order quickly.  Don't be shy!  :)


Store: http://www.chestersgarage.com

The store is running and _should_ work properly.  Please email me at mark at chester family dot org if you have any problems on the site.  This is still a work-in-progress, but I should have it nailed down pretty quick.

Full-sized image: http://www.chestersgarage.com/wp-content/uploads/2010/03/IMG_1676-e1269324901608.jpg


Hey, my first post here. Are you still looking for beta's? I am building my LED array right now. I have 5/8 channels done and Ive already got some testing done with the ELN's and a Mega. A guy in NY sent me a shield to test for him and its working very well. Its outputs 10V that the ELNs need to Dim.
The only I see with yours, I havent read everything yet, but it seems it will only run 9 LEDs. Most of the decent ones for fish tanks are 3W, so 9*3W=27W.
I have a video I can send you of me just messing around with my array to get it to dim.
My tank is a 135g and Im using 42 XPG's and 42 XRE LEDs with 4XELN's.

The only real thing left for me is packaging and programing. The program, or sketch as its called, is kicking my butt. Thats what really brought me here, help with that.
O' and if you see the video, thats only my second day of having the mega in hand. Huge learning curve!!!


Well, I already have the fully tested product for sale, so I don't need testers any longer.  But if you PM me, I'll send you a code for a one-time discount on the kits.

The number of LEDs the Power LED Shield can drive at once depends on which Puck modules you install.  At best-case and with the right power supply, you should be able to drive 3 parallel strings of 8 LEDs per channel, for a total of 96 LEDs on a single shield.  Now that's only in theory and has not been tested.  However, I have seen many cases where a string of 6 LEDs can be driven by a BuckPuck, using a 24 volt power supply.  So if you did three parallel strings of 6 LEDs per channel, you would have 72 LEDs per shield.

These would have to be 1W LEDs (for a total of 72W) and you would need 1000mA BuckPucks in all 4 channels.  If you had higher wattage LEDs, you could still get around 72-96 Watts total.  It would just require a different connection pattern and the right power supply.

If you want to post your LED's specs, I can give you a schematic for the best possible utilization of the shield.


I've updated the store with fully built kits and additional documentation.  Scroll down to the "Additional Resources" section for Application Examples (PDF).



Aug 25, 2010, 02:07 am Last Edit: Aug 25, 2010, 02:08 am by mikevolzer Reason: 1
Hi koyaanisqatsi,

I'm looking to drive 10 cool white and 10 blue Cree XR-E 1W LEDs each color on a separate channel using your board. Do you have a recommendation for drivers that I should use?


Thanks for your help.


Hi Mike,

Sounds like a reef aquarium setup?

Those will run great with 4 1000mA BuckPucks and a 24V power supply.  Run 5 of each LED per BuckPuck and assign two BuckPucks to one PWM pin so they function as one channel, and the other two BuckPucks to another PWM pin.  That will give you a channel for the blue and a channel for the white.



It's actually for a 125 gallon tank of African cichlids. I just like the blue light to bring out some more of their colors. I think I've settled on 10 cool-white Cree XP-G and 10 royal blue Cree XP-E.

Now I'm looking at power supplies, am I correct in saying that I would need a 24V 4A power supply to run all of these LEDs?

That would be 4 1000mA BuckPucks, with 5 LEDs on each in series. I don't plan on running the cool-whites at their max of 1.5A.

What do you think I should use as a power supply?

On a side note I saw on your projects that you've also developed an aquarium controller specific for dimming lights at certain times. You said something about adding a real-time clock to it, is this something that is built into the Arduino or something that can be created through programming the chip?

Thanks much for your help, I'll be making a purchase on your website soon.


Awesome!  Thanks Mike!

You'll have about 75W of LED load, plus inefficiency of the drivers and whatever the Arduino uses (from the 5V reg on the shield).  I'd suggest a 24V 6.5A supply so you have some overhead available for the Arduino and some fans to keep the LEDs cool.  This MeanWell 150W unit is what a lot of the reef keepers use:

That controller project you saw is a SparkFun.com proto-shield with a ChronoDot from macetech.com, plus a DS18B20 OneWire temperature sensor and fan controller I built for a customer.  It works with the Power LED Shield for scheduling and thermal management of the LEDs.  This: http://www.chestersgarage.com/store/arduino-shields/fan-temp-rtc-proto-shield/ You talk to the ChronoDot within your sketch to get the date and time.  It also has the 1-second square wave pin assigned to pin 2 so you can get an interrupt every second.  It's not really specific to reef tanks, and I'm going to make it into a another shield/kit as a nice addition to the Power LED Shield for any project.  But I'd be glad to build the proto-shield for you if you're interested.



Just noticed I never posted the latest schematic:  

Full res image available at http://www.chesterfamily.org/pictures?g2_itemId=10299


Hi koyaanisqatsi,

Your shield is exactly what I need as without seing it I have already ordered 4 buckpuk 3021-D-I of 1000mA :) but unfortunately your store shows your shield as sold out :\ Is there any other way of getting one ?


Eek!  I didn't get the info out quick enough!  Sorry!

I'm revving the board to V2 which doesn't use BuckPucks.  I ran out of stock sooner than I anticipated and haven't had a chance to post the details of the new board yet.  I hope you don't get stuck with them (or you can use them for something else?)

Email me (address on my web site) and we can talk timing and availability.


So on this note...

Power LED Shield V2 is on its way.  It's a total redesign, using a higher capacity driver module by Recom Power (RCD-24).

Comparison of major features between V1 and V2: (V1 / V2)

Max input voltage: 24 / 36
Max output voltage: 22 / 33
Max output current: 1000mA / 1200mA
Max LEDs in series per channel: 6 / 10
Channels assignable to PWM pins: 3,9,10,11 / 3,5,6,9,10,11
Dimming method: trimpot + PWM / trimpot + PWM to analog conversion

Plus I fixed a few bugs and annoyances.

I'm especially happy with the PWM to analog conversion for dimming.  One of the big problems I have with PWM is using it to dim things like a bicycle headlight.  When you're moving, the PWM makes for a psychedelic experience - and it's sort of dangerous.  Also, analog dimming increases the efficacy of the LEDs because they produce more light per watt at lower currents.

One last feature I'm still working on is a logarithmic (or exponential) dimming curve.  The human eye senses light on a non-linear curve.  What looks twice as bright is actually about 10x as bright.  And what looks half as bright is actually 1/10 as bright.  I think the shield will be much more useful with this feature.

Go Up