Introduction: Handheld Dimmable LED Flashlight (from an Old Vacuum Cleaner!)

About: I've been making Instructables since I was 13. Now, I mostly make videos of my projects, however I'm still active here, so don't hesitate to reach out! Sick with a deadly disease called DIY-itis!

Close to two years ago, I was given a small car vacuum cleaner. It died after a few months, so I took it apart. About at that time I also saw DIY Perks' DIY "Sun-Blaster", so I knew EXACTLY what I was going to do with the enclosure!

I've been needing a flashlight when going outside for walks w̶h̶i̶l̶e̶ ̶s̶e̶a̶r̶c̶h̶i̶n̶g̶ ̶f̶o̶r̶ ̶j̶u̶n̶k̶ ̶f̶o̶r̶ ̶u̶p̶c̶o̶m̶i̶n̶g̶ ̶p̶r̶o̶j̶e̶c̶t̶s̶. I already own a small, cheap, cylindrical shaped flashlight, but it's really uncomfortable to use, and keeps slipping out of my hand. I have an overnight school field trip coming up very soon, and have also been needing a flashlight for taking pictures for my Instructables, when I don't feel like hauling SpectrumLED V2.0 outside.

So... For short, I need a light-weight, battery powered flashlight that WON'T SLIP OUT OF MY HANDS ALL THE TIME AND FALL!

I think I've had enough time for procrastinating about the project.

Let's get started!

(Watch the YouTube video: LINK FOR MOBILE VIEWERS!)

Step 1: ​What You'll Need:

Want to make this project? Here's what you'll need, or at least what I used!

For those who aren't able to salvage parts for free, I've added some links to eBay below. Keep in mind that these parts can be acquired at a hardware store, or anywhere else online. If you don't see something that you think should be here, or would like to know more about a specific tool/part that I used, feel free to ask in the comments.

I made it for FREE since I already had everything that was needed on hand. I mean, I bought the dimmer, the LED, and the battery for a different project so...


Hardware, Materials & Consumables:



  • Soldering iron
  • Drill
  • Drill bit set
  • Hot glue gun
  • Screwdriver
  • Knife

Subjects: Electronics, Electronics Teardowns, Lighting

Approximate Time: 3 hours

Difficulty: Medium


Step 2: The Battery

After opening up the enclosure and removing all of the small pieces of plastic that weren't needed, I placed the battery at the bottom, marked where the switch was located, and drilled a 10mm hole (which I enlarged later). This is done so I can reach the tiny switch that's on the battery with my pinky.

I glued the battery and wires of the battery in place, making sure that the switch was still accessible through the hole that was previously drilled. Keep in mind that you're gluing a Li-ion battery with hot glue, and many things can go wrong!

Why does this plastic smell like CA glue!?

Step 3: Glue in the Heat Sink

I mixed up some 2-part epoxy, and then glued in one half of the heatsink that I chose to one side of the vacuum cleaner enclosure. If I glued it to both sides, I wouldn't have been able to open the flashlight later on!

Step 4: Making the Power Jack & Connecting the Wires

I made this specific part close to two years ago for a different project, so please forgive me for the obvious lack of pictures. Let's imagine that I made it now:

I soldered a 2.5mm power jack onto a small PCB that was clamped in my vise, and then soldered a red (+) wire, and a black (-) wire, which will allow me to get power from the battery without having to cut off the male power jack. The PCB and all of the contacts/wires were then insulated with hot glue.

I do my best to avoid soldering as much as possible, so I used some screw clamps to connect the battery to the adapter, the adapter to the resistor* and the input of the dimmer. The output of the dimmer will be soldered later onto the LED. Another advantage of using these is that I can replace the resistor with a diode easily if needed.

*The battery I'm using supplies 12.6V, and the LED that I'm using should receive 12V maximum. To lower the voltage a bit, I added a 1ohm resistor.

Step 5: Gluing and Soldering the LED

I squeezed a small amount of thermal adhesive into the heatsink, which was then squeezed by the LED that I pressed onto to the heatsink.

After it had dried, I soldered the wires of the output of the dimmer to the LED (+ to +, - to -), I had to drill a small hole in the enclosure as it was needed for the wires to pass through.

Step 6: The Charger, and the Last Step for the Dimmer

I drilled an 8mm hole in the top, and hot glued the charging jack of the battery, so I could charge it through the hole.

I hot glued the dimmer onto the top after drilling a hole so the wires could pass through the enclosure.

Step 7: The Reflector / Coverer Thingy

This LED emits light at pretty much 180°, and I want to concentrate the beam to less than 180°, since it blinds me if I move raise my hand. I planned on using a small magnifying glass that I already had to do that, but unfortunately, that didn't work well (in terms of connecting it) so I might buy a proper lens on eBay.

Until then, I decided that a reflector would do. I found a small plastic (salsa?) container, and cut the bottom and cap off with a knife. I wrapped gorilla tape all along the outside, cut the remaining pieces that overlapped off with a knife, and glued it right in front of the LED with TONS of hot glue!

This is good enough. Probably even better than a lens!

Step 8: ​DONE! | More Thoughts | Video!

See it in action, on Youtube!

Some more thoughts:

  • Add a diffuser, and turn up the color to be a bit warmer (higher kelvin, I believe)?
  • This enclosure can also be 3D printed!
  • Why is drilling into plastic is so fun?

I will be giving away free Instructables memberships to members that make their own handheld flashlights from old vacuum cleaners based on this Instructable. Will you be the first one?


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