Hacklet 43 – Flashlight projects

Mankind has always looked for ways to light up the night as they walk around. Fires are great for this, but they aren’t very safe or portable. Even kept safe in a lantern, an open flame is still dangerous – especially around cows.  Enter the flashlight, or torch if you’re from the other side of the pond. Since its invention in 1899, the flashlight has become a vital tool in modern society. From patrolling the dark corners of the city, to reading a book under the covers, flashlights enable us to beat back the night. The last decade or so has seen the everyday flashlight change from incandescent bulbs to LEDs as a light source. Hackers and makers were some of the first people to try out LED flashlights, and they’re still tinkering and improving them today. This weeks Hacklet focuses on some of the best flashlight projects on Hackaday.io!

light1We start with [Norman], and the LED Flashlight V2. Norman built a flashlight around a 100 Watt LED. These LEDs used to be quite expensive, but thanks to mass production, they’ve gotten down to around $6 USD or so. Norman mounted his LED a custom aluminum case. At this power level, even LEDs get hot. An extruded aluminum heatsink and fan keeps things cool. Power is from a 6 cell LiPo battery, which powers the LED through a boost converter. It goes without saying that this flashing is incredibly bright. Even if the low-cost LEDs aren’t quite 100 Watts, they still put many automotive headlights to shame! Nice work, [Norman].

light2A tip of the fedora to [Terrence Kayne] and his Grain-Of-Light LED LIGHT. [Terrence] loves LED flashlights, be he wanted one that had a bit of old school elegance. Anyone familiar with LEDs knows CREE is one of the biggest names in the industry. [Terrence] used a CREE XM-L2 emitter for his flashlight. He coupled the LED to a reflector package from Carlco Optics. The power source is an 18650 Lithium cell, which powers a multi-mode LED driver. [Terrence] spent much of his time turning down the wooden shell and aluminum tube frame of the flashlight. His workmanship shows! Our only suggestion would be to go with a lower profile switch. The toggle [Terrence] used would have us constantly checking our pockets to make sure the flashlight hadn’t accidentally been activated.

light3Harbor Freight’s flashlights are a lot like their multimeters: They generally work, but you wouldn’t want to trust your life to them. That wasn’t a problem for [Steel_9] since he needed a strobe/party light. [Steel_9] hacked a $5 “27 LED” light into a stylish strobe light. He started by cutting the power traces running to the LED array. He then added in an adjustable oscillator circuit: two BJTs and a handful of discrete components make up an astable multivibrator. A third transistor switches the LEDs. Switching a load like this with a 2N3906 probably isn’t the most efficient way to do things, but it works, and the magic smoke is still safely inside the semiconductors.  [Steel_9] built the circuit dead bug style, and was able to fit everything inside the original plastic case.  Rave on, [Steel_9]!

If you want to see more flashlight projects, check out our new list on Hackaday.io! That’s about all the time we have for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

10 thoughts on “Hacklet 43 – Flashlight projects

  1. I had a large 39 LED light from Harbor Freight. It didn’t last long, after about 20 minutes I smelled smoke and saw some coming out of the light (which lost one entire row). When I opened it and checked inside, the LEDs were arrainged in 3 sets of 13 LEDS in parallel and all 3 in series with a single blackened crispy 1/4w resistor. It takes only one faulty shorted LED to dump excess current through 2 remaining clusters of LED and burn the resistor out.

  2. I like Horror Frights digital multimeters, there is usually a coupon for a “free” one in the back of automotive magazines e.g. Street Rodder, Hot Rod, I probably have 8 or 10 of them now, and have a couple of coupons in my car to “buy” another.
    I keep one in my toolbox, one on my desk, one in my backpack, one in each car, about 3 spares…

    They are much more reliable than the flashlight(s)

  3. I took one of the blue HF ones that a friend had that wouldn’t work and found the battery clip was stamped bad. Any light that uses three tiny cells of old tech power is just going to get wired up to an old cellphone adapter with a small resistor to set the current at 20 mill per LED. To run this blue HF light I opened a wall wort and modded the voltage divider on the feedback to the opto diode so, no waste at all.
    Those blue lights are all parallel if I remember, on throwaways if one shorts the whole thing becomes a throwaway. The wall wort ain’t good for much more current, so it seems safe. I stick it under part of the metal desk so it lights up the floor, handy anytime parts fall or I grab it to see into gear. A light always on wired so it can’t walk off. I took off the chrome mask and over cover of plastic so they don’t heat up from cold as much. The C/V power supply should not cause too much drive range. Oh’ and the switch was jumped so all are on. There are tiny resistors as fuses in branches of the circuit still all in parallel.
    There are active fora on flashlights on the web for sure. Candlepower forum is one.

    1. Just checked aliexpress.com and they have one source for such cheap ones. But I don’t know if you get anything workable from it.
      But you are right, generally they start at about $13.- on sites like dx.com and aliexpress.

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