This UV Light is intended to be used at night along with a white sheet and a 12 volt battery to collect insects. The three way switch on the side allows for two modes of operation as well as off. When the left side of the switch is pressed in, the light will be on until the battery is fully drained. When the switch is in the middle position, the light is off. When the right side of the switch is pressed in, the light will only turn on if the battery is above the cutoff voltage and the ambient light is below the threshold level. The default voltage cutoff is 10 volts and can be adjusted. The brightness threshold can be adjusted as well.

Usually the light trap should be operated with the switch in the right position where the UV bulb is controlled by the light and voltage sensors. This keeps the battery safe and allows you to set up the trap before it gets dark without wasting battery life. The left position of the switch is useful if you want to test the light during the daylight or if you want to manually override the low voltage cutoff in order to continue collecting. See the video below for a demo of the light and switch.

The photos in this Instructable were taken from at least three different light traps that I assembled. There were slight differences between the traps, including step order, so if the photos don't look exactly like your light, don't worry about it. Just follow the steps in order and pay attention to the part of the photo that the step is talking about.

Supplies

7/3/24 Update: Some of the supply links have broken since I wrote this. The items are probably still available if you look around on ebay and amazon, potentially under different sellers. I can only vouch for the exact components I bought and put together so if you buy something else, caveat emptor.

Tools:

Laser Cutter
Pliers
Soldering Iron and Solder
Small Crescent Wrench
Ruler
2 mm and 2.5mm L Wrenches
Multimeter (optional, but can be helpful)
Wire Stripper
Scissors
Flush Cutter
Small Screwdriver Set
Spring Clamps
UV Blocking Glasses (UV can harm your eyes. Wear UV blocking glasses or at the very least, avoid looking at the bulb.)

Supplies:

Step 1: Laser Cut Acrylic Pieces

Download the appropriate file. The files are either .ai or .dxf. Select the file type and the version, (ventilated or unventilated), that you prefer. After several field tests I recommend the unventilated version. It's less leaky in rain and doesn't seem to overheat despite the lack of ventilation.
Send the file to your laser and use it to cut the pieces from 3mm or 1/8 inch clear acrylic.

Step 2: Initial Assembly

Place M3 screws into the acrylic piece as shown in photo 1. Make sure that the piece is oriented in the same way as the picture. Use a small crescent wrench and a 2 mm L wrench to fully tighten Nyloc nuts onto the screws. See photo 2.

Place the blue photocell module onto the screws as shown in photo 3. Set aside the long white wires that come with the photocell for now. Make sure the orientation is the same as in the photo. Press the photocell module all the way down until it is resting against the tops of the Nyloc nuts.

Do the same with the voltage cutoff module as shown in photo 4. Make sure the orientation is the same as in the photo. Press the module all the way down until it is resting against the tops of the Nyloc nuts.

Cut two pieces of 22 gauge wire, one black and one red, to 13 cm lengths. Strip a few mm of insulation off of the ends. See photo 5.

Slide the two wires under the photocell module as shown in photo 6.

See photo 7. Put one end of the wire in the receptacle labeled Vcc. Put the other end in the leftmost slot on the other side of the photocell module.

Cut and strip another black and white pair of 13cm wires. Run them under the two modules as shown in photo 8.

See photo 9. Attach the right end of the red wire to the lower right receptacle on the voltage cutoff module. Attach the other end to the same Vcc receptacle on the photocell module as the first red wire. Attach the right end of the black wire to the receptacle just above the red wire on the voltage cutoff module.

See photo 10. Plug the bottom two ends of the black wires into the GND receptacle at the bottom of the photocell module.

Use a small crescent wrench and/or a pair of pliers along with the L wrench to tighten 6 Nyloc nuts onto the M3 screws above the modules as shown in photo 11-12. Note the circled nuts. The lower right screw on each module won't receive a nut because there is not sufficient space.

Find the piece that is shown in photo 13. Plug it into the square hole between the two modules as shown in photos 14-15. Use Weld-on to fasten it in place.

Plug the long white wires that originally came with the photocell module into its white receptacle as shown in photo 16.

Wrap the excess white wire around the photocell module as shown in photo 17.

Cut a 3 cm long piece of heat shrink that is a large enough diameter to fit over the acrylic piece from step 11. See photo 18.

Twist the white wire around the acrylic piece and slide the heat shrink over it to keep it in place. See photo 19. Use a lighter to carefully melt the heat shrink without damaging anything. Make sure that the photocell on the end of the wires is facing up and unobscured by the heat shrink. See photo 20.

Step 3: Assembly II

Arrange 5 of the acrylic pieces as shown in photo 1.

Press the four sides into the square piece as shown in photo 2 and use Weld-On to fuse the pieces together.

Find the rounded corner pieces shown in photo 3. Check to make sure that one of the M4 steel hex nuts fits inside the corners that have hexagonal holes. If it doesn't, you either have the wrong size hex nut or a laser kerf issue. Do not proceed until you have corner pieces that the M4 nuts fit inside of.

Place one of the corners that has a hexagonal hole in it in the bottom corner of the box as shown in photo 4. Use Weld-On to fix it in place.

Place an M4 steel hex nut in the hexagonal hole as shown in photo 5.

Place one of the corner pieces that has a round hole over the hex nut as shown in photo 6. Use Weld-On to fix it in place.

Repeat steps 4-6 for the other three corners.

Cut the tip off of a dental syringe as shown in photo 7.

Pull the plunger out of the syringe and mix several mL of Gorilla glue epoxy. Scoop the epoxy into the back of the syringe and replace the plunger. See photos 8-9.

Use the syringe to apply epoxy to all of the seams inside the acrylic box. See photos 10-11. Be careful not to get epoxy in the threads of the nuts or in the way of the top of the box where the lid will go later.

Cut two lengths of the 18 gauge wire, one 20 cm and the other 28 cm long. See photos 12-13. Separate the black wires from the red.

Strip the ends of the black wires and twist them together as shown in photo 14.

Take the leftover 28 cm red wire and cut an 8 cm length from it as shown in photo 15. Strip the ends and bend one of them at a 90 degree angle as shown in photo 16.

If you aren't already familiar with EC5 connectors, watch this youtube video.

There are two kinds of brass pieces for the EC5 connectors, male and female. Solder the bent end of the red wire and the twisted ends of the black wires to the Male brass pieces. See photo 17 and don't use the female pieces by mistake.

The blue plastic EC5 pieces also come in male and female. Press the brass end of the red wire into the + side of the Female blue piece of plastic with the rest of the wire sticking out to the right. See photo 18.

Stand the blue plastic on its end and use a screwdriver with a flat or square head to press the brass into the plastic until it is firmly seated. You should hear a click. See photo 19. This can take a fair amount of force. Be careful not to slip and push the screwdriver into your hand.

Repeat the process for the brass piece attached to the black wires. See photo 20.

Cut a 20 cm length of 18 gauge wire. See photo 21.

Strip the ends of the wires and separate the black and red wires for about 5 cm as shown in photo 22.

Cut two 1 cm long pieces of heat shrink that have a large enough diameter to fit over the metal tabs on the Female Dean's plug. Place the heat shrink and the gray plastic piece of the female Dean's plug over the separated ends of the red and black wires. See photo 23.

Solder the wires onto the FemaleDean's plug and make sure that the red wire is attached to the side with a +. See photo 24.

Slide the heat shrink pieces over the wires and tabs and use a lighter to shrink them in place. See photo 25.

Press the gray plastic piece over the heat shrink as shown in photo 26.

Find the piece of acrylic shown in photo 27.

Press the completed Dean's plug through the acrylic piece as shown in photo 28. This may take some force.

Find the acrylic pieces shown in photo 29.

Check that the epoxy on the acrylic box is cured. If it isn't, wait until it is.

Place the four small acrylic pieces to the acrylic box as shown in photos 30-34, but don't use Weld-On yet.

Place the Dean's plug acrylic piece over the previous pieces as shown in photo 35. Use Weld-On liberally to attach all the pieces.

Press the 3-position switch into the rectangular hole in the side of the acrylic box as shown in photo 36. Make sure that the double line is towards the right.

Press the female EC5 connector into the hole between the switch and Dean's plug as shown in photo 37.

Find the three acrylic pieces shown in photo 38.

Place the acrylic pieces over the EC5 connector as shown in photos 39-40. Use Weld-On liberally to attach all the pieces.

Slide heat shrink over the red wire coming from the EC5 connector. Solder it to the middle prong on the back of the switch, then slide the heat shrink over the prong and use a lighter to shrink it. See photo 41.

Take the two 20 cm lengths of 18 gauge red wire leftover from previous steps and solder them to the two remaining prongs on the back of the switch. Use heat shrink to cover the exposed wire and prongs. See photo 42.

Step 4: Assembly III

Find the two acrylic washers as shown in photo 1. Use Weld-On to attach them to the base of the acrylic piece that houses the light and battery sensors. Make sure to line up the holes before attaching them. See photo 2.

Find the ballast and place it upside down as shown in photo 3.

Cut the thin red and gray wires short as shown in photo 4-5. These will not be used for this project.

Put heat shrink over the shortened wires and use a lighter or heat gun to shrink them, then use electrical tape to tape the wires to the bottom of the ballast. See photos 6 and 7. Make sure the wires don't get in the way of the notches at the ends of the ballast where screws will go later.

Apply Gorilla glue epoxy where the switch and the two plugs meet the acrylic and where the wires plug into them. Make sure not to get epoxy in the way of where the lid piece will go later. See photo 8. Wait until the epoxy has cured before proceeding to the next step.

Twist the long black wire from the EC5 connector together with the black wire on the left side of the ballast. See photo 9.

Solder the twisted wires together. Make sure that the end of the white wire sticks out farther than the black wire and try not to get solder on that end so that it remains flexible. See photo 10.

Slide a piece of heat shrink over the two twisted wires as shown in photo 11.

Bend the end of the wire that sticks out past the heat shrink at a right angle as shown in photo 12. Then use a lighter on the heat shrink as shown in photo 13.

Run all of the wires through the rounded rectangular hole at the bottom of the acrylic box as shown in photo 14. All of the wires will need to be attached through this hole in the following steps.

Slide heat shrink over the thick red and yellow wires on the side of the ballast as shown in photo 15.

Slightly separate the black and red wires that are attached to the Dean's plug as shown in photo 16.

Solder the red wire from the Dean's plug to the thick red wire on the ballast and the black wire from the Dean's plug to the yellow wire on the ballast. See photo 17.

Slide the heat shrink over the solder and shrink it with a lighter or a heat gun. See photo 18.

Find the diode shown in photo 19. Note the light colored band towards one side of the black plastic part.

Bend the wire at the end that doesn't have the light colored band at a right angle and then cut it short as shown in photo 20. Make sure you have the orientation right or else your electronics will release their magic smoke when you turn them on later.

Cut the other wire on the diode to about half of its length. Double check to make sure that your diode looks exactly like photo 21.

Locate the wire that is attached to the three way switch closest to the edge of the acrylic box. See the highlighted wire in photo 22.

Take the red wire from the previous step and the white wire that is attached to the ballast and put them together. Slide a piece of heat shrink over both of them as shown in photo 23. Twist the ends of the wires together as shown in photo 24.

Solder the long wire on the diode to the two wires that are twisted together. Double check photo 25 to make sure that you soldered the correct side. The light colored band on the diode should be on the side that is soldered to the twisted wires.

Orient all of your components as shown in photo 26.

Find the small black wire that is coming from under the photocell and the two black wires that are soldered together as shown in photo 27. Put them both into the top right slot in the photocell and tighten the screw. See photo 28.

Find the red and white wires that are attached to the diode as shown in photo 29. Put the end of the diode in the middle slot of the photocell as shown in photo 30.

Gently place the ballast so that its notches light up with the raised holes on the acrylic as shown in photo 31. Be careful not to knock any of the wires out of the photocell. Use the 2.5 mm L wrench to attach the ballast with two M4 screws and nuts as shown in photo 32.

Attach the last red wire from the 3 way switch to the green plastic slot on the low voltage sensor that is labeled +VIN. See photo 33.

Attach the last black wire from the EC5 plug to the slot next to the one that you plugged the red wire into. See photo 34.

Use Weld-On to attach the lid to the acrylic box as shown in photo 35. Do not close the box yet.

Step 5: Battery to Box Wire

Cut about 70 cm of 18 gauge wire, separate the ends on one side by a few cm, then strip them. Slide heat shrink over the stripped ends. See photos 1-3.

Find 2 of the Female brass pieces for an EC5 connector. See photo 4.

Solder the wires to the brass connectors and then use a lighter or heat gun to shrink the heat shrink over the exposed wire. See photo 5.

Use a screwdriver to press the brass pieces into one of the Male blue plastic EC5 pieces while making sure that the black wire goes into the slot marked - and the red wire goes with the +. Apply Gorilla glue epoxy around where the wires meet the plug, but don't allow it to drip onto the male part or else it won't fit into the female plug. See photos 6-7. Wait for the epoxy to cure before continuing.

Slide a large and a medium piece of heat shrink over the other end of the wire. The larger piece should cover the wires where they meet the plug and the medium piece will stick out behind and underneath the larger piece. See photos 8-9.

Use a lighter or heat gun to shrink the heat shrink. See photo 10.

Separate the wires at the other end by about 20 cm and strip them. See photo 11.

Take the red alligator clip and lay it next to the red wire. Slide the red plastic piece off of the alligator clip and onto the red wire. See photos 12-13.

Put the bare copper of the red wire into the groove in the alligator slip. Use a pliers to crush the copper tabs and hold the wire in place. See photo 14.

Solder the wire to the copper alligator clip. See photo 15. Slide the red plastic back onto the clip as shown in photo 16.

Repeat this process for the black wire and alligator clip. This wire is now ready to carry electricity from the batter to the electronics box.

Step 6: Box to Bulb Wires

Cut about 10 feet or 3 meters of 16 gauge wire. See photo 1.

Separate the wires at each end of the cable by several cm and strip the ends. See photo 2.

Put a medium/large piece of heat shrink, 2 small pieces of heat shrink, and a gray plastic Dean's plug piece over the ends of the cable. See photo 3.

Solder a male Dean's plug on one end of the cable and a female on the other. Polarity for the first plug doesn't matter, but make sure that the polarities match for the second one. This can be done by carefully tracing the length of the cable. The two strands in the cable can also be distinguished by the faint lettering that is stamped on just one of them. See photo 4.

Slide the small heat shrinks over the exposed metal wires and use a heat gun or lighter to shrink them. See photo 5. Do this for both male and female plugs.

Press the gray plastic piece onto the rest of the Dean's plug as shown in photo 6. Do this for both male and female plugs.

Hang the ends of the cables vertically and drip Gorilla glue epoxy into the holes in the gray plastic and onto the wires themselves. See photo 7.

Wait for the epoxy to cure, then slide the medium/large heat shrink over the wires all the way up to the gray plastic. See photo 8. Use a heat gun or lighter to shrink the heat shrink as shown in photo 9.

Slide a large piece of heat shrink over the Dean's plug until it is flush with the end of the plug as shown in photo 10. Use a heat gun or a lighter to shrink the heat shrink as shown in photo 11. The cable is now finished. It is used to carry electricity from the box to the next wire which you will start making in the next step.

Open the bag with the UV bulb wires. Keep the two white cables and discard the hardware. See photo 12.

Take one of the two white cables, separate the two wires at the end of it by a cm or so, and strip the ends of the wires. Use the flush cutters to cut off the pre-soldered ends of the wires. See photos 13-15. Do the same with the other white cable.

Attach the twisted ends of the white cables to a Male Dean's plug using the same technique as as you used for steps 4-9 with the 16 gauge wire. For this plug though, the polarity doesn't matter. See photos 16-17. The cable is now finished. It will carry electricity from the 10 foot (3m) cable to the UV bulb.

Step 7: Testing and Adjustments

Set the switch on the box to the middle position, which is off. Clip the alligator leads onto the battery and plug the other end into the box. Plug the short white wire into the box and attach the other ends to the UV bulb. See photo 1.

Press in the side of the switch that has a single vertical line. The UV bulb should turn on while the LEDs on the sensors should remain off. See photo 2.

Press in the side of the switch that has two vertical lines. The LEDs on the sensors should turn on. The UV bulb may or may not turn on depending on the brightness of the room. See photo 3.

Turn off the lights and close your windows so that the room is dark. The bulb should now be on. use a Phillips screwdriver to turn the adjustment dial on the photocell counter-clockwise until the bulb turns off. Then turn it 1/4 turn clockwise so that the bulb is on again. See photo 4. Turn on the lights to confirm that the bulb turns off.

The cutoff voltage module has two black buttons below the LED voltage display. Press the one on the left to display the cutoff voltage, which is probably set at 10 volts for the default. Press and hold the left button for 3 seconds until the display starts flashing. Press the left button to increase the cutoff voltage by 0.1 volt and the right button to decrease it by the same amount. I like to set mine to 11.3 volts, which means that the battery will be disconnected when it drops to about 10% of a full charge. When it is set to the correct cutoff, stop pressing buttons and after a few seconds the display will stop flashing. See photo 5.

The UV electronics box is now completed. Use 4 M4 screws and the 2.5 mm L wrench to attach close the box and be careful not to pull or pinch any wires and don't cover up the photocell sensor. See photos 6-7. Once it is closed, test it one more time to be sure that the wires are still properly attached.

Step 8: Setting Up the Trap

Tie a rope between two tree branches at least 5 feet off of the ground in the area where you want to trap insects.

Hang a sheet from the rope and hold it in place with spring clamps at the top. Hang additional clamps from the bottom to minimize movement due to wind. See photo 1.

Place the battery, cables, and UV lamp at the bottom of the sheet.

Attach the bulb to the white cables and plug the end of the white cables into the black 10 foot (3 meter) cable.

Run the cables up the back of the sheet and hang the bulb over the top on the front of the sheet. See photo 2. Hold it in place with a spring clamp.

Plug the end of the 10 foot cable into the electronics box.

Set the switch on the box to off, which is the middle position.

Attach the alligator clips to the battery and then plug the other end into the electronics box.

Put on your UV blocking glasses, or at least avoid looking at the bulb while it is on.

Flip the switch to the 2 vertical line setting. The light and battery sensors should come on and the UV bulb will come on as soon as it is dark enough.

Collect insects!

Introduction: UV Light Trap for Insect Collecting