Turn A Free Flashlight Into LED Strips

Harbor Freight is always trying to sweeten the deal by throwing in a free flashlight, or a multimeter with a CAT III rating so poorly-met it might as well be a hand grenade. We usually donate the meters to our local hackerspace, but the flashlights tend to accumulate around the shop. Aside from borrowing the occasional magnet, we’ve not found a good use for them till now.

[Ben Brandt] realized that a ultra-low cost board such as the one likely to be in a free flashlight is probably going to contain a very easily hackable single-sided board. Which is exactly the case here. Once the plastic casing is removed it’s only a quick trip to the saw until you have four fresh mini LED strips.

[Ben] uses his hacked loot to build a neat little, “Thanks For Watching,” sign. We can picture lots of places these could fit in the occasional project, and the work to break these up into parts is less than making equivalent boards with any proto technique. We love his wooden battery compartment. Video after the break.

34 thoughts on “Turn A Free Flashlight Into LED Strips

    1. The free DMVs are good for project meters. Cut the leads and wire them directly into the project if, for instance, you’re interested in voltage and current draw from your prototype.

      Apropos the CAT III rating, I’ve checked the *accuracy* and found these meters to be very accurate – comparing favorably to my higher-end meters.

      1. When I taught Intro to Computer Hardware at the local community college, I’d regularly sacrifice a couple of Harbor Freight meters in the “don’t do this unless you want to die” section of the course.

      2. Their accuracy is fine, and since they are essentially free I have several attached to the pegboard in front of my bench and use them to probe circuits in various places. Just ignore the HV rating and only use them for low voltage stuff, I’ve never used mine for over 50v so far.

  1. I’ve often thought about how to install a charging circuit inside those lights so I can just put three high capacity NiMh cells in and never have to bother with replacing the carbon zinc or alkalines.

  2. The auto white balance fluctuating constantly is maddening! I’m not sure what this was shot with, but watch the color of the grey background at the beginning as he takes his hands in and out of frame.

    It’s a nice build though!

        1. I typically record the work on my phone, mounted on a tripod, and capture the “shop sounds” with the phone’s built-in mic. I record the voiceover separately using a good value-priced USB microphone (Samson GoMic) with a cheap pop filter connected to my PC as I edit the video together.

      1. Or you could shell out just a few bucks for a better camera app. I installed Cinema FV-5 on my Android phone after getting annoyed at the focus seeking of the default video app (resulting in slight blurring a few times a minute). I don’t remember the price, but I’m pretty sure it was less than $5. FV-5 locks white balance and focus at the start of the video. My only gripes with it are: to take a photo from within the app, you have to buy the FV-5 camera app too and it won’t save to my SD card for some reason.

  3. Hope he was using a particle mask when he cut the PCB on the bandsaw. Even cheap paper based PCB’s are nasty on the lungs. Need I comment on the hazards of wood dust too?

  4. I just find a current capable phone charger and a small resistance to make an always on flashlight. No more batteries, leaving on, loosing, winking, and blinking. Sticks up on any steel surface. Leave on stuck in dark under bench areas.

  5. “Aside from borrowing the occasional magnet, we’ve not found a good use for them till now.” How about as a flash light? I love these things and use them all the time. The magnet is great to have it held somewhere like my hood or trunk or other places I might use it, and it lights up quite nicely, especially for being free!

  6. b2ben, and for your next project, you could turn one of this flashlights into a circular videolight for your cellphone which goes around the lens, so you will have way better lighting at near distances :-)

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.