Introduction: Free UV Flashlight ( If You Have the LED's )

This Instructable is to show you how to take apart a FREE Harbor Freight Flashlight and replace the LED's with UV LED's.


If you have the LED's it is FREE! If not then it's potentially 11 Flashlights for 45¢ each.

But it's all about the Build Anyway!

Step 1: Title , Reason, and Uses

"Free UV Light "( If you have the LED's )


"How to Modify a POS Flashlight into a UV emitting tool for detecting Vaseline and Depression glass due to the fluorescent properties exhibited by glass with Uranium content"

Harbor Freight usually has FREE Coupons for 3 items in almost every circular and even online ad's. The do vary a bit but you can count on them being one of these:

  1. Free 9 LED Flashlight <( what we will be using )
  2. Free 5x7 Tarp ( won't last long but free )
  3. Free 25ft Tape Measure ( the last about a year )
  4. Free Multimeter ( Total Junk!!! get only if you don't have a real Multimeter )
  5. Free 6 piece Screwdriver set ( If you just need a spare for emergencies )
  6. Free Scissors ( last about 3 months )

If for some reason your Harbor Freight does not have the flashlight you can check your Dollar Tree if they have a 9 LED flashlight it is the exact same piece of garbage.

Now the reason I make UV Flashlights is I collect Uranium glass and live in one of the Antique Belts I also hit up lots of yard sales. The problem is that there is a lot of green glass made in the 60's and early 70's that might have the same color characteristics as true Uranium glass. Even Depression glass varies a lot in green color. The green is actually the Iron Oxide not the Uranium. It is easy to tell a nice Victorian Canary piece and even true Vaseline has a particular look but when you get into the darker green Depression glass then it sometimes gets a little hard and I really only care about how it looks in my china cabinet under the UV lights.

You could also make this for your kid an invisible ink pen from the dollar store.

You could use it to check on the cleanliness of your hotel room ( but somethings are best left unknown )

For hunting Scorpions

I am sure there are many other uses.

Now on to the making part.

Step 2: Tools and Supplies

This Instructable will really only REQUIRE one must have tool and that is a Soldering Iron ! You could really wing the rest but I am giving you a full list of what I usually use.


  1. Soldering Iron
  2. Small wire cutters or Nail Clippers
  3. Small Vice or Something to hold PCB ( not required but helpful )
  4. De soldering tool or De soldering wick ( not required but helpful )
  5. 5/8" or 16mm Socket and small extension ( not required but helpful )
  6. Small Jewelers pliers ( not required but helpful )


  1. Solder
  2. Flux
  3. 1 - Donor HF 9 LED flashlight
  4. 9 - UV LED's

Now I have lots of various LED's. So technically it's not something I had to buy. If you need UV LED's Ebay has them for 100 for under $5 after shipping

Regardless if you think you will ever need that many I have less than 20 left out of 100 so you do use them. I think I got them for a Time Fountain project that I never did.

Step 3: Disassembly

  1. Unscrew bottom cap
  2. Remove Batter pack
  3. Remove the Lens/Reflector/PCB ( SEE BELOW )

First I take something like a file or in this case I used some type of cuticle tool or something and scrap around the outer edge of the lens. If the tool is slightly curved make sure it is facing outward. You will hear a scraping sound and will see that you scraped a line in the housing around the lens. You only need to make out pass around the lens. Not sure if it is actually necessary but the point is if the did glue the lens on it will help scrape off any excess and make it easier to come out, with this one it wasn't but I have damaged the lens before because it did not want to give.

Removing the Lens/Reflector/PCB without damaging it can be
tricky depending on what version or who made the flashlight. The one in this Instructable must be a newer version. The previous ones never said Harbor freight on the sides of them and the PCB was round. This on is an octagon. Older ones are harder to get out as the usually have a leg or two wedged bent over the reflector as to make a connection with the housing.

Take a 16mm or 5/8" socket with small extension and place it in the bottom of the housing against the edges of the PCB. You might be able to get away with a deep socket if you don't have an extension. Now you can apply steady pressure to the top until it gives slightly. It is only about 1 to 2 mm in the housing.

It is very important steady pressure! Do not hammer it down or bang on it or you risk damaging the lens/ PCB/ or even the reflector!

This on was easy but I have had old ones that just didn't want to give they probably used adhesive . If this happens then you can use the method I always use although overkill for this unit.


For those with an Arbor Press or Hydraulic Press. I use my Hydraulic Press. Once the head is on the extension just 1/4 of a pull down will free up the Lens/Reflector/PCB. DON"T DO MORE THAN THAT YOU WILL JUST CRUSH IT! Then it can be just pushed out by hand. This unit could have been pushed out by hand from the start.

Step 4: De Soldering and Soldering

You now have the Lens out and the reflector and PCB.

Pull the PCB with the LEDs out of the reflector and set the lens and reflector to the side.

Flips over the PCB and De Solder the spring for the + side of the battery

Now De Solder the LED's.

I am not going to go into Soldering or De soldering as I would imagine anyone who is going to do this already has that skill set down.

Now it is important to note the orientation of the LED's . Think of the center as + and the outside as negative, Or the Cathode ( Big Pointy part ) facing inward toward the Anode ( Little part ) , or as far as the LED's legs go Small Leg outside , Long Leg inside. Or just look at the LED's your removing and you get the proper orientation.

When Soldering the LED's . I do it one at a time. I also bend the legs at a slight angle rather than just inner and outer before I solder More like the the teeth of a saw blade. This is to make sure everything stays on its proper trace, if you look at the pictures you will understand why. After you solder each one cut off the excess leg.

I left two of the Cathode legs long to hang over the reflector like the way the lights used to be. This will made a much snugger fit as well as insure there is good contact to complete the circuit as opposed to the 4 little solder points at the edge of these new versions.

The last LED I Solder in is the center one. This on I do orientate the legs up and down so to the follow their respectable trace. The spring goes on the Anode but you can figure that out by looking at the traces or the image above.

Before you put the spring back on you might want to protect that (-) soldering point, so when the spring bends it doesn't actually touch it and short out the light. You could use a small piece of electrical tape but I prefer just to paint a dab of nail polish on it to insulate it. Nail Polish can also be used for PCB repair but I am not going into that. Color does not matter just No Metallic ! after it dries than solder the spring onto the positive.

Step 5: Reassemble and Test

1 ) First place the PCB in the Reflector. You might have to wiggle it around a little bit and it will be snug but if you soldered your LED's in straight it will go in.

2) Then push in place the reflector. If you did the 2 legs it will be very snug and should not require any adhesive. ( either way don't do adhesive yet! )

3) Reassemble the light, battery and end cap and TEST!

4) If it works go to step 5 if not?

4a) Remove PCB . If you have some wires and an adjustable power source then put the center positive point in the PCB and the negative on any of the points on the outside trace, if it lights up then try adjusting the spring to be more center.

4b) Make sure that negative in the center of the PCB is insulated.

4c) Put it back together with everything but the end cap and put a wire to the housing and hold it to the negative bottom of the battery pack while pushing it in. If it works then the button on the bottom could be messed up.

4d) Mess with it some more

5) If the reflector is loose then remove it and put a small amount of adhesive in the top of the housing but toward the lower part of where the reflector sits. Then push in the reflector with PCB completely in and wait till it sets.

6) Now you can press the lens it. I didn't need any adhesive just direct pressure and press it in good. It's not going anywhere and it really isn't necessary even if it ever did come out. It's cheap plastic.

Now to give it the Real TEST!

Step 6: Testing on Various Vintage Glassware

To show the reason I make these and always have one on hand.

The first picture is a collection of various glassware most is uranium but 3 are not and just for Example.

The second picture shows various fluorescence of the proper pieces. The image is a little deceiving though . The glass to the very left of the pet turtle bowl is not the glow on the stem is from the other pieces, the stem of the glass to the left of it is, The plate to the upper right bowl is actual Vaseline Glass but does not have a real high content of uranium, it glows a little but do to lighting didn't show up well.

Again I make these so if I am at a yard sale or Antique store, Fleas Market or where ever if I see something for sale that I might want. I can pick it up and test it.

After that it just goes in one of the cabinets.

Make It Glow! Contest

Participated in the
Make It Glow! Contest