Introduction: UV LED Exposure Light for Screen Emulsion

By
About: Longtime DIYer liking the Instructable platform used mainly in the past for learning and ideas, but now hope to give back by sharing ideas I've found and developed myself.

My friend, a few weeks ago, contacted me about helping him make an Ultra Violet light for his printing applications. He was looking for a high-power (approximately 100-watt) UV (410nm) LED light that he said would help to speed up and improve the curing of his print jobs. Of course he text messaged me because his knowledge of LEDs is similar to my knowledge of printing and curing...Not good - but hey, what are friends for!

The project turned out great and while it's niche, it turns out the general concept could be applied to many other applications, so I decided to document it and share!

I came up with the idea from gear I had seen on LEDSupply.com. They mainly sell LEDs, LED drivers, Optics, Strips, etc..But, they also have a few cool LED kits with all the products required to build your own reef tank lights and grow lights, which I thought could be varied slightly and used for this project. I called them up and they agreed to customize their reef tank kit with UV LEDs special for us. The kit I was originally looking at is here if you want to see it, but I also listed out as many components and links as possible below. The major difference between the kit on their site and what we have is the amount and configuration of the UV LEDs (more later).

LED Parts & Accessories (Pictured)

  1. (1) MakersLED Heatsink Kit: 14" Heatsink, Fan, Acrylic Lens & Mounting Hardware
  2. (2) MakersDriver 2Up Pro with 700mA MeanWell Drivers (2 per unit)
  3. (2) Custom UV LED Boards: 18 LEDs per Board (6 LEDs per channel @ 3 channels)
  4. (1) 48Vdc Power Supply with Power Cord: 2.2 Amp output capable of 100-Watts
  5. (1) Arctic Silver Thermal Grease
  6. (24) Red & Black 24 Gauge Wire

Tools Required

  1. Wire Strippers
  2. Screw Drivers (Phillips & Flat Head)
  3. Drill
  4. Pencil
  5. Heat Shrink (Optional)

Step 1: Organize & Plan

Again, this project turned out great. It went smooth and was relatively easy to do and didn't require many tools...BUT, we definitely laid it all out and planned ahead. Here were the main areas we focused on before jumping into the build:

  1. Complete Kit: We placed all the parts and components out to get a feel for what we had and to make sure everything we needed was there (pictured).
  2. Overall Set-Up: The fan needs to be in the center of the heatsink, which means the location of the MakersDrivers have to be at each end of the heatsink. And, because each MakersDriver needs to have wires going to the LEDs, the best place to drill holes was on each end (Pictured).
  3. LED Board Layout: Each LED board has 5 channels which can contain as many as 6 LEDs in-series. Only channels 2, 3 & 4 were populated on our boards; for a total of 18 LEDs on each board. There are numbers marking each channel and corresponding numbers and polarity marking each screw-in terminal block.
  4. LED Driver Set-Up: These units are designed to take 48Vdc on the input and have 2 separate outputs labeled as channel 1 and channel 2. One channel can run as many as 14 LEDs, since we have 18 on each board we have to use both outputs. One output from the driver will run the LEDs in channel 2 and the second output from the driver will run the LEDs in channels 3 & 4.
  5. Things to Note: Test all wire connections with a slight tug. We had a wire come loose on the MakersDriver after completing and needed to unscrew the driver from the heatsink to access the screw terminals. Not a huge deal, but worth noting.

Step 2: Drill

Once we were happy with the location of the boards and how they matched up on the opposite side with the drivers we marked their location with a pencil (help with step 3) and marked spots to drill. The holes only need to be large enough to fit (4) 24 gauge wires (ours were plenty big). Once the location of the holes were marked we went ahead and drilled through from the side where the LEDs are placed.

Step 3: Mount LEDs

With the outer lines of the boards marked onto the heatsinks we were able to:

  1. Squeeze a line of grease down the center of each channel (pictured)
  2. Spread grease over the entire surface (pictured)
  3. In each corner (pictured) start screw and nut
  4. Carefully slide the nuts into the correct channel, while keeping the board orientation as originally planned (It might be easier to start the nuts in the channels before attaching the screw and nut to the board, but either or will work). I say that because sliding each board into the channels took a few minutes and was the most frustrating part of the whole build

Step 4: Wiring Stage 1

As I mentioned in Step 1 LED channels 3 & 4 are wired together in-series and require extra wiring to jump channel 3 to channel 4. To accomplish this:

  1. A wire was added jumping from the negative of channel 3 to the positive of channel 4. This puts both channels in-series with each other (12 LEDs). The other output from the MakersDriver ends up running channel 2 (6 LEDs) and is described further in Step 6.

Step 5: Driver Prep

The MakersDrivers each use two Meanwell 700mA power modules which needed to be connected:

  1. Match the pin configuration of the Meanwell drivers with the hole configuration of the MakersDriver
  2. Snap into place
  3. Wash, Rinse, Repeat (Pictured)

Step 6: Driver & LED Connections

Using red (positive) and black (negative) wires we first connected them to the output of the driver as well as the 48Vdc input to the driver. Then we fed the output wires from channel 1 & 2 down through the hole and to the appropriate screw-in terminal channel of LEDs. Lastly we connected the male fan plug to the female plug on the driver. Here are the specifics:

Example, Channel #1 Output from Driver to Channel #3 & Channel #4 LEDs (left board) :

  1. Positive (red wire) from output of driver goes to positive screw-in terminal block #3
  2. Red jumper wire (completed in Step 4) goes from negative screw-in terminal block #3 to the positive screw-in terminal block #4
  3. Finally to complete the circuit the negative output from the driver goes to the negative screw-in terminal block #4

Example, Channel #2 Output from Driver to Channel #2 LEDs (left board) :

  1. Positive (red wire) from output of driver goes to positive screw-in terminal block #2
  2. Finally to complete the circuit the negative output from the driver goes to the negative screw-in terminal block #2

Rinse and repeat for the second LED board.

Step 7: Power Connections

Before screwing down the fan, drivers and hardware to the heatsink we tested the unit by connecting the power:

  1. In Step 6 we connected wires to the input of each LED driver
  2. The next step was to run these four wires out one side and connect them to the power supply
  3. For example, the red wire (positive) from one driver we connected to the far right V+ (Pictured) and the black wire (negative) we connected to the far right COM (shown on power supply). The other driver connects to the other two V+ and COM (negative) locations
  4. Finally we connected the 72" power cord to the power supply. The wire with writing runs to the line voltage (L) and the other to the neutral (N)
  5. We double-checked all the connections and powered it up

At first it didn't appear to work, but that was because the dimming knobs were all turned down. We turned all 4-channels in the opposite direction and we had light.

WARNING: We didn't look for long because UV light can damage the human eye!!!

Step 8: Make It Pretty

Finally we attached all the hardware:

  1. Both drivers mount to the top of the heatsink
  2. Fan also mounts to the top of the heatsink
  3. Acrylic Lens slides into heatsink (optional)
  4. End Caps and Plugs for Heatsink (cosmetic)
  5. Heatshrink around Power Wires (optional)

My buddy can't hang this from the ceiling because it shines up from underneath a table, but my job here was done at this point! And, again the boards can be build with LEDs for growing plants, reef tanks, etc., or as we found out with UV. I think, don't quote me, with all the customization the project ended up costing him less than $500.