Portable LED/RGB beam + controller

Hi !

I am currently designing a compact portable led beam system and would have liked to have your input regarding what boards and accessoires you would recommend in order for it to perform properly.

The goal of my project is to control an array of eight high power RGB LED's (the likes of Cree Mc-E's), seven of which are mounted in series under a focusing lens and sitting on a 90mm/3.5 inch round plate, said LED's would then be operated by a control box (wired to the Led's through a 2m/6.5 ft cable) which includes one of the following LED's as a color indicator and with which I could adjust the light's color/output and other settings described bellow.

The controller's casing should be big enough to fit both the Arduino, pcb, buttons/fader and eventually a rechargeable battery that would power the electronics and the lights (however if it proves to be too much of a hassle the battery could be external)

Arduino did seem to be the way to go since this is a rather compact standalone unit that did not require DMX connectivity.

The drawing included in this post should give you a better understanding of what I'm currently looking for.

Regarding the attached drawing :

1 = Hue selection (rotary switch) scrolls between the different colors of the rgb spectrum
2 = Strobe (push button / mechanical switch)
3 = Breathing effect (push button / mechanical switch) triggers a fade in / fade out loop
4 = Blackout (push button / mechanical switch) temporarily switches off the LED lights
5 = Power output (digital fader)
6 = Led color indicator shows a sample of the LED unit color/effects on the controller
7 = On/Off switch
8 = Led cabling connecting the controller to the LED unit
9 = Auxilary power input connecting the controller/LED's to an optional power supply

not included in the drawing, the USB in. The Power switch / strobe / blackout and breathing effect buttons also have dedicated light up indicators when switched on

Thank you for your input, all your recommendations are welcome.

Cheers

IMG_4216 (2).jpg

IMG_4216 (2).jpg

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...not included in the schematics...

You forgot to post the schematic!

My bad !

By the way I made a typo right there, I meant to include a simplified diagram (included in this message) and not detailed schematics.

Cheers.

Shall I post your image for you again?


Ah. Not what I was expecting. Do you have an electronics schematic that you could post please?

Thank you for posting the diagram,

I do have schematics and specs for the LED's themselves but I do not have proper documentation for the rest of the build (since I do not know which board would be best for this specific task and how I should go about wiring everything to it).

Ok, post those. The forum sticky post will show you how to post links correctly.

Here's the schematics for the LED's themselves as well as some extra info :

Maximum Drive Current : 0.7 A per LED die
Max Power (W) : 9.5 W
Max Light Output (lm) : 751 lm
Maximum Efficacy at Binning Conditions (lm/W) : 99 lm/W
Typical Forward Voltage : 3.1 V per LED die White @ 350 mA
2.1 V per LED die Red @: 350 mA
3.4 V per LED die Green @ : 350 mA
3.2 V per LED die Blue @ : 350 mA
Maximum Reverse Voltage : 5 V
Binning : 2- and 4-Step EasyWhite®
Maximum ESD Withstand Voltage : 8000 V (HBM per Mil-Std-883D)

There'll be eight of them running in series.

Got it for the pictures.

There'll be height of them running in series.

Did you mean eight?

If so, you are going to need a 30V+ power source. What batteries do you plan to use?

Eight it is ! (includes the offset LED color indicator mounted in the control box which requires a fraction of the output of the beams)

I was thinking about a hobby grade lithium polymer pack which could handle such a load for a short period of time, I do not plan on running the LED's at their maximum output tho which would ease the load on the battery pack.

However I also think that having a Dc input built in the system would be a great idea when using the fixture in a static fashion since It could enable me to run the lights for longer once plugged into the power supply.

Myoriginal post has been updated with the proper drawings and updated info.

Cheers.

I was thinking about a hobby grade lithium polymer pack

Can you post a link to an example power pack? I have not seen them with 30V+

These kind of batteries are generally used for powering electric bikes or big multirotors, here's a few exemples :

https://hobbyking.com/en_us/zippy-compact-5800mah-8s-25c-lipo-pack-xt90.html

http://www.batteryspace.com/hi-powerlifepo4li-ionmodule30v10ah5x2rpack300wh45arateprewiredwithpolyswitch.aspx

I might not need to have that much power tho since I do not plan on running the led's at their maximum output and only seven LED's are sitting under the lens, the 8th one runs on the controller as a color indicator.

Ok, I see.

One of those LEDs won't be suitable as an indicator for your control panel. Even at reduced power, it would be far too bright to look at, even wearing sunglasses! If it's in series with the other 7, you can't reduce its power without reducing the others to the same degree.

So behind the lens, you plan to 7 LEDs? The green diodes have the highest forward voltage (3.4V) so 7 in series would be about 24V, so a 30V battery has an extra 6V which should be enough to run the constant current drivers. Sparkfun make some that might be suitable (link). Only problem is, that has only 3 channels and you need 4, so you could add one of these to make the 4th channel.

You will also need a substantial heatsink to bond your LEDs to, otherwise they will have very short lives. I guess you will need a solder oven to do that, I don't see how it could be done with a soldering iron because you need to solder the heatsink pad underneath the led to the heatsink substrate.

I planned on using a frosted cover on top of the indicator in order to reduce the lumen output but I understand that it could be too much, is there any other way to get such an indicator on the control unit ? (I will not be able to see the LED beam myself so having an indicator is mandatory.)

I do plan on using 7 leds behind the lens yes, if it sounds overkill I might be inclined to use less as long as we can get the lens to be fully lit with an uniform beam coming out of it.

As far as heatsink goes I do plan on having all the LED's mounted on star shaped pcb's which are then mounted on dedicated individual elliptical finned heatsinks welded on a 90mm aluminium sheet which is then cooled by a 80mm fan.

What you ideally need is a 5mm RGBW led. But I've never seen one. You could either simulate the for with an RGB led, or maybe mount an RGB and a white led her your frosted cover.

Yep there doesn't seem to be any on offer, I know that Adafruit offers an RGBW solution tho, could this be paired to the beam Led's in your opinion ?

Yes, that's a potential solution, although it would make the software and hardware a bit more complex than it needs to be because of the built in driver chip. That will require another Arduino pin, a new library and some extra code. So I would try ordinary, separate 5mm RGB (common cathode) + white LED first to see if you are happy with the appearance. With those leds, you can wire (with 4 series resistors) the LEDs in parallel with the pwm signals going to the led drivers, so no extra Arduino pins used and no change to the sketch will be needed.

Got it, having the RGB and W 5mm Led's under a proper lens could work fine and save us quite a bit of extra work, thanks for the advice.

Now to the fun part then : the controller itself, I was wondering what arduino board could handle both the Led drivers and the 3 push buttons (with their led indicators), the digital fader and the rotary switch (as well as the DC/battery in).

Any basic Arduino can do this. If you have one already, such as Uno, then fine. If not, I recommend Nano 3 or Pro Mini (you will need a separate usb-serial convertor to program the Pro Mini, but this convertor can then be used again on other projects). Don't be put off by the word "Pro" because except for the need for usb-serial convertor, it is just as easy to use as Nano 3, Uno etc. Actually in my opinion, Pro Mini and Nano are easier to use than Uno if you will build your prototype on breadboard, which I would definitely recommend.

For a beginner, a pot will be easier to use than a rotary switch.

However, I don't think any Arduino can be supplied with 30V, so perhaps. Dc-Dc convertor will be needed to make 5V from 30V. The Arduino, LEDs and switches will not need much current, less than 500mA.

Perfect, I do need to get a new board for this project, the Nano 3 does seem to be the way to go since it has the same micro chip and more in/outs compared to the mini pro (which could help if I decide to expend on the project in the future), is there any difference between the two that I am not seeing ? (Safe for the usb in)

Noted for the pot.

The converter did seem to the way to go indeed.

Pro Mini and Nano 3 probably have the same number of pins, very similar to Uno. All 3 based on same chip.