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Make: Projects

Brownie Pan LED Light Panel

Roll your own photography light panel for a fraction of the cost of pro units.

LEDPanel_final-13

This project first appeared in MAKE Volume 38, on page 56.

Opinions are mixed on LED lighting, but anyone who has ever done location work won’t be able to deny their utility — they’re lightweight, they have very low power draw, and they generate very little heat. They’re an excellent tool to have in a one-man band style of shooting. They’re also expensive. But now, with the proliferation of LED lighting kits for home use, you can build a very good equivalent to $500 off-the-shelf products for under $100. More importantly, if you’re careful you’ll come away with a project that looks good — and won’t scream, “I built this in a shed!” — and that might be handy, depending on who your clients are.

The core of this project is the adhesive-mounted strands of LED lights that you can cut and resolder into any configuration that strikes your fancy. These are usually sold in kits that come with an external power supply and an inline dimmer. Unfortunately you won’t be able to use this dimmer for video lighting purposes. Dimming for LED lights is achieved through a process called pulse-width modulation, which introduces a very rapid flickering that dims or brightens the light depending on the length of the cycle. The included inline dimmer operates at a relatively slow cycle — it looks fine to your eyes, but in camera you’ll see a pretty noticeable flicker. We’ll be using the guts of an external dimmer to get the results we need.

There’s an awful lot of soldering in this project, but none of it is very tough, so if you’re still intimidated by the process, this is a good project to help you build your skills. Overall the project is fairly simple, and you can complete it in around 4–6 hours depending on how smoothly your soldering goes. The cost of parts will set you back around $70 to $100, but you’ll likely have plenty of plexiglass and corrugated plastic left over to build more of these panels in the future.

The dimmer on the left is an inline dimmer that comes with many LED kits. It is unsuitable for video use. The one on the right is much better suited for our needs.

The dimmer on the left is an inline dimmer that comes with many LED kits. It is unsuitable for video use. The one on the right is much better suited for our needs.

Steps

Step #1: Cut the panels.

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  • Cut the plexiglass to a 12½"×8" rectangle.
  • Cut the corrugated plastic to a 6"×10” rectangle.
  • Drill four ¼" mounting holes in the corners of the corrugated plastic panel, ½” inward from each edge of the panel. The holes should form a 5"×9” rectangle.

Step #2: Prepare the housing.

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Brownie Pan LED Light Panel
  • The baking tin will form the overall housing of the lighting panel.
  • Using the mounting holes in the corrugated plastic as your guide, mark out 4 holes on the back of the housing (I recommend using painters or masking tape for marking) and drill four ¼” holes, starting with the 1/16" bit for a pilot hole.
  • In the bottom of the long edge of the housing, drill 3 additional holes: one ¼” hole in the center for the mounting hardware, and two 5/16” holes for the DC jack and the dimmer knob. Put the hole for the DC jack no more than 2” away from the center hole; keeping the jack close to the mounting hardware will make cable management easier when using the light.

Step #3: Prepare the housing, cont'd.

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Brownie Pan LED Light Panel
  • At this point you’ll need to prepare the inside of the housing for adhesives. If you bought a tin with a teflon coating you'll get a nicer finish for the light, but you'll need to do some additional prep.
  • Use your grinding wheel to roughen the metal (and remove any teflon coating) around the inside of the ¼” center hole that you’ll use for the mounting hardware.
  • If your pan is teflon, also remove about a 1"×2½” swatch of teflon roughly 2” above the holes for the DC jack and dimmer knob. This is where you'll mount the PCB from the dimmer.

Step #4: Mount the internal threading.

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Brownie Pan LED Light Panel
  • Finally, use the grinding wheel to score one side of a ¼-20 nut. Mix up a small amount of your two-part epoxy, following the directions. Use the epoxy to bond the nut to the inside of the panel, centered on the ¼” center hole. This nut will become the internal threading you can use to mount the panel to any tripod stud.
  • TIP: To get a better bond, you can use the stud from the ballhead to hold the nut in place while the epoxy dries, but you may end up permanently fusing the ballhead to the housing. This may not be a concern for you, so proceed as fits your needs.
  • Set the panel aside to let the epoxy set.

Step #5: Cut and solder the LED segments.

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  • You can only cut the LED strip at the marked areas, which appear every 3 lights. Starting with the end of the LED strip that has the loose positive and negative wires, cut the strip into fourteen 10” segments. Set the remaining part of the spool aside for future projects.
  • Prepare 14 segments of speaker wire 2"–3" long, by splitting and stripping each end.
  • Now use the wire segments to solder all the LED segments back together. I find the best technique is to melt a small dot of solder onto each terminal of the LED segment, and then heat up that solder while poking the wire end into it. Connect all the LED segments, end to end, making sure you don’t cross up the positive and negative terminals.
  • Use a voltmeter to verify continuity through the circuit to check your work.

Step #6: Mount the dimmer and jack.

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Brownie Pan LED Light Panel
  • Disassemble the PWM dimmer and remove the PCB and potentiometer. Use double-sided foam tape to mount the PCB to the inside of the housing, on the patch of teflon you removed earlier.
  • Use a 3"–5" length of speaker wire to connect the DC jack to the input terminals on the dimmer PCB, following the manufacturer's instructions for both. Connect the positive and negative wires from the first segment of the LED strip into the output terminals of the dimmer PCB.
  • Mount the DC jack and potentiometer into their holes in the bottom of the housing. Connect your DC jack to power and check your circuit to make sure everything lights up, and dims when you twist the potentiometer.

Step #7: Mount the LED panel.

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  • Mount the corrugated plastic panel to the housing by fitting the Allen screws and washers into the coupling nuts.
  • Peel the adhesive backing from your first LED segment and mount it to the corrugated panel just above the washers. Mount each consecutive segment in the same way, zig-zagging your way up the panel until all segments are mounted and you run out of room.
  • Check your circuit again to make sure no solder joints have worked loose, and resolder as needed.

Step #8: Mount the plexiglass cover panel.

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  • Finally, cover the ends of the plexiglass panel with masking tape, and use the original holes at the ends of the baking pan to mark matching holes on the plexiglass. Drill ¼" holes at your marks, then remove the tape and mount the plexiglass cover to the front of the housing using the remaining Allen screws, washers, and nuts.
  • If you have access to a bandsaw, you can use it to cut the plexiglass cover to match the shape of the baking pan.
  • Use the grinding wheel to carefully clean up any rough edges.

Step #9: Go use it!

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  • You're done! You can use the threaded hole at the bottom of the ballhead to mount to any ¼” tripod stud, or use the shoe adapter included with the ballhead to mount to any shoe mount.
  • Because the LEDs generate little heat, you can use household items like baking parchment to diffuse the light. Binder clips can be used to attach diffusion material or gels to the outside of the housing.
  • There’s a lot of variation you can do with this project, from panel size to color temp to lots of other configurations. Happy shooting!
Tyler Winegarner

Tyler Winegarner

Tyler Winegarner is a filmmaker and photographer based in San Francisco. When he's not busy shooting, he's down in his shop grinding, soldering, or hacking at his next project. Follow him at @therealtylerw.


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