Instructables
I have been drooling after some nice led panels for a while now, but just can't justify spending a fortune to buy them. 
These LED panel give a nice soft light source for photography, saves electricity, robust and won't heat much.
I am not a professional photographer, just enthusiast that sometimes has professional justify to build silly stuff like this.

I decide to do two big ones and one smaller that i would add battery later for outside shooting.



 
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Step 1: Planning and ingredients

Picture of planning and ingredients
My coal was to keep budget under 100 pounds for 3 led panels. Some how a 12v strip light felt like the best way to start. Also 12v meant that its easy to find power for. car batteries, power supplies and so on.  How much light I would want? Well let see 5 amp feels like maximum amount of power I want to draw and 5M 300-SMD 5730 LED strip rope light white looked like a good model. (although later found it to be too cool near 9900k) there is a warmer version also. 5730 LED where 0.5 watt each and strip light was split in group of 3 LED's, so these can be cut between these groups.  That was a good start for some calculations this site came handy.

http://ledcalculator.net/

So now I know that my bigger panels would take 99 leds and smaller would have 81 and you can left only 36 on by switch, if you want to increase battery life.

So where to house them. First looked into buying some aluminium briefcases for it, but then remembered that I had previously bought some aluminium school cooking containers from 70s for possible iPad and laptop bag, but now that project would wait and these cases would get a new purpose. I think these where perfect for the task. bigger panels where built on one container lid as one panl and botom

I wanted to able to dim this led although I know that it might be a possible problem and introduce flickering specially in low power, but then I decided that I will be mostly run them full power and I just went a head with a simple premade led dimmer.
Some switches i tried to find ones with bit of a retro style.
I think aesthetics are important I can find myself enjoy something I have built more if it also looks good.

List of parts

3x Led dimmer 12/24 volt 8 amp  
price of one 9£ 

3x power supply 5 amp
price of one 5£

Led strip
5M 300-SMD 5730 LED strip rope light white
40£

3x power switch
price of one 2£

3x power plug
price of one 2£

aluminium tape

some electric wire

total 94£

additional stuff

plexiglass
20£

mounts
14£

3x photography light stand
price of one 9£

Step 2: Led placement

Picture of Led placement
First I tested lights in groups this is important because I found out that 12 of my LEDs did not light up.
Remember to buy more than you need.
So after getting rid of non working ones I cutter the strip in smaller right length strips. And placed them pre planned position. And started to cut out wires and place switches on right places to get an idea if all would fit well.

I laid few layers of tape under led strips for isolation and then temporarely taped them in place.
clear tape works here fine as it does not block reflections from the aluminium container. 

Step 3: Dimmer

Picture of Dimmer
I opened one of the dimmers to see what it had eaten. See if i can reduce the size of it and I was really pleasantly surprised that it was perfect layout and it even had dimming control with wire so I could place it freely.

note: Remember these kind of dimmers are very basic and works with Pulse Width Modulation principle. witch means that when led is dimmed it actually cuts the current for really short periods rapidly. You can't see this by eye, but when used for video or photography camera can pick up these cuts and it looks like a flickering or produce artefacts when shooting video.
This comes more problem when lights are dimmed a lot and high speeds for shutter time is used. Problem goes away when full power is used.

Step 4: Holes

Picture of Holes
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After that I took few measurements for rest cables. Then I took the LEDs off and drilled holes for DC power input, dimmer control Knob and on/off switch. It's good to drill your holes for mounting also. If you are going to add  plexiglas or gel in front it's also time to drill mounts for that. For me it was a late update so I did this in the end.

note: buy round DC plug so you can mount it easy just by drilling one hole. My power supply had DC 2.5mm male plug so i bought corresponding 2.5mm female plug.

Step 5: Testing electronics

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It was time to test electronics and see if everything would still works.

note: be careful that no electric connectors touch metal or short circuit when you test. duhh :)

Step 6: Taping to final position

Picture of taping to final position
Then I covered all connectors with electric tape for insulation and used aluminium tape to tape strips in place. So far with my tests these panels are very cool and the aluminium body displaces the heat very well.

note. I used aluminium tape to maximise reflecting surface on the panel. 

Step 7: All done

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small_panel_back_d.jpg
main_picture_ready_d.jpg
Voila everything works. I made some measurements. Light temperature 9500k too cool so for now i decided to add panel of frosted slightly brown tinted Plexiglas which works as protection, light diffuser and changes light to more workable 7700k not perfect but closer.

This is a first version of these lights. I am really happy about the results, but here are few things i might re-think or do differently for next version.

Mounting. well this didn't go as planned I first bought flashgun mounts that seemed like perfect place to start, but company that sold them could not get them delivered and returned my money. I was running out of time to enter 4th Epilog Challenge  so I went a head and made them from mounts that I already owned ment for surveillance cameras.
Not ideal,flimsy and i don't recommend.

warmer leds or even adjustable color temperature

i would place every panel in own case though having two panels in one case lid and bottom takes less space. its not handy when you just need one also gives more freedom in control, switch and power plug placement. By placing them only one end can make more robust design.

Light intensity not measured with professional equipment just simple sensor.

without plexiglass

next to panel 5700 lux
1m 250 lux
2m 100 lux


with plexiglass

next to panel 2700 lux
1m 170 lux
2m 80 lux


Thanks to my girlfriend for being the best assistant ever.

Thanks to everybody for reading :)
alcurb5 months ago

Very nice project. I added your project to my FotoTrix collection.

I'm going to build one but with discrete straw-hat 8mm LEDs: 100-each 6000k 100k mcd and 100-each 2700k 90k mcd. I plan to lay them out in a checkerboard pattern. Each color string would be controlled by it's own brightness control. The idea is that I can select the color temperature I want. My concern is how to dim the LEDs without using PWM for the same reasons you stated above about shooting with high shutter speeds. One old-school solution I found was to use a rheostat pot, but the excess energy would be dumped as heat and I don't want that. It would need to be a non-PWM circuit. I'm currently searching for ready-made solutions. I want to keep my power supply adapters simple and light-weight, so I plan on using lap-top power adapters with no voltage controls. Regarding the PWM solution, could that be saved by adding a capacitor in parallel with the PWM output? My hope is that with the capacitor the output may look more like continuous DC rather than pulsed DC. Mkuha, would you please try it and let me know if the adding the cap works?

alcurb alcurb5 months ago

I think I answered my own PWM-to-smooth-DC question: https://arduino-info.wikispaces.com/Analog-Output

isashach3 years ago
Great project! I wanted to do something like this for a while but I couldn't quite figure out which batteries to use and stuff. I would recommend that you wouldn't buy your LED strips for 40 £ a roll, when you can get them for 3-4$ a meter...
Also, have you tried using 1 watt LEDs? They're very efficient, and I'm quite sure they would work much better, and your final product would be much smaller ;)
where do you get your led strips by the meter?
I get them directly from a factory in China, however eBay has some OK prices too. However it is much more cost efective if you buy them in 5 meter rolls.
Could you supply a link
alibaba.com ;)
nickvkn3 years ago
What are those metal panels called or where can I buy some?

mkuha (author)  nickvkn3 years ago
sorry i don't know what they are called. I found them from junk store. I only know that they where used for cooking at schools in 70's. searching aluminium cooking container i have managed find similar containers few times, but not much info about them.
I just know them as "Baking Trays", nothing special or complicated. I used Foil backed with cardboard for a similar project once.

Nice work.
Instead of the servo why didn't you use just a run of the potentiometer
kmurray243 years ago
I think adding some mirroring on the panel would make it all the brighter?>!
mkuha (author)  kmurray243 years ago
Yes first i was thinking of adding that aluminium tape also to containers bottom, but i felt that the bounce back light is not that massive and the material is fairly reflective already. Panels are really bright and easily enough for my lighting needs. Also being aluminium you could actually bit of work right tools polish it to close mirror finish, if you want to see the trouble :)
This project is very similar. Check the links for super cheep components. Going to make a couple at some point.


mkuha (author)  sensoryhouse3 years ago
that's cool to see that other people have took a similar approach. I was wondered why i haven't seen more something like this, one of the things that inspired me to do this.
What a fantastic project. It's clear that you where successful meeting your coal. Congrats...
lol @ coal
mkuha (author)  WhateverForever3 years ago
thank you! very nice of you.
tigerbomb83 years ago
you could go to a hobby store get some li-po batterys and a voltage regulator and make a battery pack for when you are out and about
mkuha (author)  tigerbomb83 years ago
yep i like that idea also, battery back was in plans already from beginning. I left some room for that in the smallest panel, so i can place it in. Haven't got around to do that yet. Big panels if needed can be run from external battery.
did you enter this in to the make it glow contest
mkuha (author)  tigerbomb83 years ago
now i did ;) thank you!
mikeasaurus3 years ago
I like the addition of the plexiglass diffuser, have you thought about other types of material as light filters?
mkuha (author)  mikeasaurus3 years ago
Thank you! yeah i have thought few other options also. I think i will end up adding some kind of mount so i can use thin light and diffuser gels that come in rolls. maybe magnetic mount, but that's still in thinking phase :)
i started making schematics for panel that used RGB leds
mkuha (author)  tigerbomb83 years ago
Great! I am very interested, keep me posted on progress.