In the very late 1990s, something amazing was invented. White LEDs. These magical pieces of semiconductors first became commercially available in 1996, and by the early 2000s, you could buy a single 5mm white LED for less than a dollar in quantity one. A year or two later, an astonishing product showed up on infomercials airing on basic cable at 2 a.m. It was a flashlight that never needed batteries. With a small white LED, a few coils wrapped around a tube, and a magnet, you could just shake this flashlight to charge it. It’s just what you needed for when the Y2K virus killed all electronics.
Of course, no one uses these flashlights now because they suck. The early white LEDs never put out enough light, and charging a flashlight by shaking it every twenty seconds is annoying. There is another technology that desperately needs a battery-less solution, though: remote controls. They hardly use any power at all. That’s exactly what [oneohm] did for his Hackaday Prize entry. He created the Undead Remote.
The dream of a battery-less remote control has been dead since your parents got rid of that old Zenith Space Command, but here it is. This is really just a shake flashlight, a diode rectifier, a large capacitor, and some glue. Shake the remote, and you can change the channel. Is it useful? Certainly. Does it look weird and is it slightly inconvenient? Also yes. But there you go. If you want an easy way to deal with batteries in your remote control, this is a solution.
The principle is well understood: use a motor in reverse and you get a generator. Using this bit of knowledge back in 2001 is what kick-started [Ted Yapo]’s Hackaday Prize entry. At the time, [Ted] was searching for a small flashlight for astronomy, but didn’t like dealing with dead batteries. He quickly cobbled together a makeshift solution out of some supercapacitors and a servo-as-a-generator, hacked for continuous rotation.
A testament to the supercapacitors, 17 years later it’s still going strong – leading [Ted] to document the project and also improve it. The original circuit was as simple as a servo, protection diode, some supercapacitors, and a LED with accompanying resistor; but now greater things are afoot.
A DC-DC boost converter enables constant power through the LED, regardless of the capacitor voltage. This is achieved by connecting the feedback pin of an MCP1624 switcher to an INA199 current-shunt monitor. The MCP1624 kicks in at 0.65V and stays active down to 0.35V. This is all possible due to the supercapacitors, which happily keep increasing current as voltage drops – all the way to 0.35V. Batteries are less ideal in this situation, as their internal resistance increases as voltage drops, as well as increasing with age.
When testing the new design, [Ted] found that the gears on his servos kept stripping when he was using them to charge capacitors. Though at first he attributed it to the fact that the gears were plastic, he realized that his original prototype from 2001 had been plastic as well. Eventually, he discovered the cause: modern supercapacitors are too good! The ones he’d been using in 2001 were significantly less advanced and had a much higher ESR, limiting the charging current. The only solution is to use metal gear servos
[VanTourist] — irked by what he sees as complicated project videos — has demonstrated that you can build a high quality, multi-function Bluetooth speaker inside three hours.
Using simple hand tools — primarily a crimper, wire stripper, razor cutter and some glue — he’s packed this repurposed GoPro accessory bag with quite a bit of tech. The main components are a Bluetooth amplifier with a spiffy knob, and a pair of 15W speakers, but he’s also added a 1W LED flashlight, 1A and 2.1A charging ports, a battery charge monitor display, and pilot cover toggle switches for style points. Despite all that crammed into the bag, there’s still a bit of room left to pack in a few possessions! You can check out the build pictures here, or the video after the break.
We have all at some point have made a flashlight. It used to be a staple of childhood electronics, the screw-in bulb in a holder, and a cycle lamp battery. If you were a particularly accomplished youthful hacker you might even have fitted a proper switch, otherwise, you probably made do with a bent paperclip and a drawing pin.
So you might think that flashlights offer no challenges, after all, how many ways can you connect a bulb or an LED to a battery? [Peter Fröhlich] though has a project that should put those thoughts out of your mind. It uses a power LED driven by a TI TPS61165 boost driver, with an ATTiny44 microcontroller providing control, battery sensing, and button interface. The result is a dimmable flashlight in a 3D printed case housing both control circuitry and a single 18650 cell which he sourced from a dead laptop. Suddenly that bent paperclip doesn’t cut it anymore.
The result is a flashlight that is the equal of any commercial offering, and quite possibly better than most of them. You can build one yourself, given that he’s published the physical files necessary, but probably because this is a work in progress there are as yet no software files.
Sometimes the hack is a masterwork of circuit design, crafting, 3D printing and programming. Other times, the hack is knowing which tool is right for the job, even when the job isn’t your regular, run-of-the-mill, job. [John]’s son lost his tooth on their gravel driveway, so [John] set out to find it.
When [John] set out to help his son and find the tooth, he needed a plan of attack – there was a large area to cover and, when [John] looked over the expanse of gravel the terms “needle” and “haystack” came to mind. Just scanning the ground wasn’t going to work, he needed a way to differentiate the tooth from the background. Luckily, he had a UV flashlight handy and, after testing it on his own teeth, realized that his son’s tooth would fluoresce under UV light and the gravel wouldn’t.
Off [John] went at night to find the tooth with his flashlight. He soon realized that many things fluoresce under UV light – bits of plastic, quartz crystal in the rocks, his socks. [John] eventually found the tooth, and his son is happier now. No soldering was involved, no development on breadboards, no high-voltage, but this is one of those hacks that is more about problem solving than throwing microcontrollers at a situation. In the end, though, everyone’s happy, and that’s what counts.
Flashlights are handy around the house, but what if you want a stealthier approach to illuminating the night? Infrared LED flashlights can be acquired at relatively low cost, but where’s the fun in that? To that end [johnaldmilligan] spent a couple hours building an infrared flashlight-gun with an LED display to venture into the night.
[johnaldmilligan] disassembled a handheld spotlight to use as the housing, leaving the trigger assembly and 12V DC charge port in place. A miniature camera was used as the video source after removing its infrared filter. Note: if you do this, don’t forget that you will need to manually readjust the focus! The camera was mounted where the flashlight bulb used to be instead of the LED array since the latter was impractically large for the small space — but attaching it to the top of the flashlight works just as effectively. The infrared LEDs were wired in eight groups of three LEDs in parallel to deliver 1.5V to each bank and preventing burnout. Here is an extremely detailed diagram if that sounds confusing.
If you’ve ever wanted to bring the brightest day into the blackest night, this flashlight shall give you sight. With a 100W LED array powered by up to 32V, this thing is exceedingly bright — it clocks in at about 9000 lumens! But the best part is that all every little detail of the build was documented along the way so that we can tag along for the ride.
The all-aluminium case houses the LEDs and their heat sink, voltage regulator and display, the AD and DC adapter and converter boards and their connectors, and fans to ensure adequate ventilation. It’s powered by a custom-assembled 6400 mAh 11.1V lipo battery or DC 20V 10Amp power supply via XLR for rugged, locking connection. The battery pack connection was vacuum formed for quick-swapping, and the pack itself will sound off an alert if any of the three batteries inside the pack run out of power. A nifty added feature is the ability to check the remaining charge — especially useful if you’re looking to bring this uncommonly powerful flashlight along on camping trips or other excursions.