Toothbrush Goes From Mouth-Whitening To Room-Brightening

Some of the hacks we see make us wonder why they aren’t already a commercial product, and this electric toothbrush turned rechargeable flashlight is one of them. Sure, these things exist, but we haven’t seen one with a dedicated charging stand. They usually just take micro USB or whatever, so it’s on you to remember to plug it in. How great would it be to have a fully-charged flashlight always at the ready, especially one in a position to illuminate the room? Although [wannabemadsci] makes it look easy, this conversion took quite a bit of doing.

Perhaps the most amazing part is that [wannabemadsci] found a halfway decent flashlight at the dollar store. Better than average, this thing has a main light, a side light, and takes 3xAAs instead of a couple of AAAs. The only issue is that the toothbrush batteries don’t quite put out enough voltage for the flashlight’s LED, so [wannabemadsci] used a booster board.

Of course, there’s a lot more to this hack than sawing off the USB connector from the boost converter so it fits. The toothbrush handle had to be modified to accept the flashlight guts, and the threads relocated from the flashlight. Since the battery charge indicator shines through the momentary button on the toothbrush, [wannabemadsci] wanted to reuse it, but it required a small board that converts it to a latching push button. Finally, the flashlight bezel had to be painted white. Paint is such an easy thing to do, and this detail makes all the difference in how professional this looks.

There’s a lot you can do with a functioning electric toothbrush as your base, like brute-forcing the pins of a lock with vibration.

Improved Outdoor Solar Harvester Now Handles All The Parts

[Vadim Panov]’s 3D printed solar harvester is in effect a rechargeable outdoor battery, and the real challenge he faced when designing it was having it handle the outdoors reliably. The good news is that part is solved, and his newest design is now also flexible enough to handle a variety of common and economical components such as different battery connectors, charge controllers, and solar panel sizes. All that’s left is to set it up using the GoPro-style mounting clamp and let it soak up those solar rays.

We saw his first version earlier this year, which uses inventive and low-cost solutions for weatherproofing like coating the 3D print with epoxy (the new version makes this easier and less messy, by the way.) It was a fine design, but only worked with one specific solar panel size and one specific configuration of parts. His newest version makes a few mechanical improvements and accommodates a wide variety of different components and solar panel sizes. The CAD files are all available on the GitHub repository but he’s conveniently provided STL files for about a dozen common sizes.

When it comes to harvesting light, staying indoors offers less power but requires a far less rugged setup. If that interests you, be sure to check out the Tiny Solar Energy Module (TSEM) which can scrape up even indoor light.

That E-Cig Battery Probably Fits Into Sunglasses

This particular e-cigarette is a little bigger than a typical cigarette, with a matching battery.

E-cigarettes use electrical power to rapidly heat and vaporize a base liquid such as propylene glycol, and that power comes from a battery. These devices are functionally straightforward but it can be a messy process on the inside. Thankfully though the batteries can be salvaged once components like heating elements either gum up or burn out.

[facelesstech] decided to use the battery from an e-cig as the power source for a smart sunglasses project, which uses two RGB LED rings to put on a light show. Opening up the device it was discovered that the battery was a straightforward lithium-polymer cell, in AAAA size. If you’ve ever torn open a 9 v battery and discovered the six diminutive cylinders inside, an AAAA cell is about the same size as one of those. However, the battery from the e-cig is both rechargeable and has a nominal voltage of 3.7 volts, which can happily drive a microcontroller project. The small battery fit nicely into one arm of the glasses, and when covered with heat-shrink, was hardly noticeable. The battery charger doesn’t fit inside the glasses, but one can’t have everything.

The ability of an e-cigarette to pump out clouds of vapor has led to some interesting hacks. One such is a DIY portable fog machine, which opens all kinds of doors for costuming applications.

A Better Charger For Your Coin Cell Batteries

Rechargeable coin cell batteries are great for all your small projects. They look exactly like regular coin-cell batteries, but in a shocking turn of events you can recharge these little guys. They can put out a reasonable amount of current, and they’re small. Just what you need for your Arduino smart watch, or whatever else the kids are doing these days.

But if these batteries are rechargeable, you need a charger. That’s where [Jon]’s entry for the Hackaday Prize comes in handy. It’s a small, cheap charger for LIR2032 and other rechargeable batteries comes in. It’s barely larger than the battery itself, and it plugs right into a USB port. How this isn’t a product already, we’ll never know.

The circuit on this coin cell charger is built from an MCP73831, a nice single cell, lithium ion and lithium polymer charge management controller. In the standard, ‘I only need to read the first page of the datasheet’ configuration, this chip can put 500 mA into a battery. Standard rechargeable coin cells only have a capacity of 40 mAh, so you’ve got plenty of headroom at 1C.

The total cost for this project was under $8 for three boards, and a BOM cost of $2 for one. That’s fourteen bucks for three of them, if you know how to solder, compared to a standard, off-the-shelf charger for about $20. Building this is cheaper than buying the equivalent product. It’s unbelievable, but true.

PTPM Energy Scavenger Aims For Maintenance-Free Sensor Nodes

[Mile]’s PTPM Energy Scavenger takes the scavenging idea seriously and is designed to gather not only solar power but also energy from temperature differentials, vibrations, and magnetic induction. The idea is to make wireless sensor nodes that can be self-powered and require minimal maintenance. There’s more to the idea than simply doing away with batteries; if the devices are rugged and don’t need maintenance, they can be installed in locations that would otherwise be impractical or awkward. [Mile] says that goal is to reduce the most costly part of any supply chain: human labor.

The prototype is working well with solar energy and supercapacitors for energy storage, but [Mile] sees potential in harvesting other sources, such as piezoelectric energy by mounting the units to active machinery. With a selectable output voltage, optional battery for longer-term storage, and a reference design complete with enclosure, the PPTM Energy Scavenger aims to provide a robust power solution for wireless sensor platforms.

Tiny PIC Clock Is Not A Tiny Bomb

It’s been a few weeks since the incident where Ahmed Mohamed, a student, had one of his inventions mistaken for a bomb by his school and the police, despite the device clearly being a clock. We asked for submissions of all of your clock builds to show our support for Ahmed, and the latest one is the tiniest yet but still has all of the features of a full-sized clock (none of which is explosions).

[Markus]’s tiny clock uses a PIC24 which is a small yet powerful chip. The timekeeping is done on an RTCC peripheral, and the clock’s seven segment displays are temporarily lit when the user presses a button. Since the LEDs aren’t on all the time, and the PIC only consumes a few microamps on standby, the clock can go for years on a single charge of the small lithium-ion battery in the back. There’s also a phototransistor which dims the display in the dark, and a white LED which could be used as a small flashlight in a pinch. If these features and the build technique look familiar it’s because of [Markus’] tiny MSP430 clock which he was showing around last year.

Both of his tiny clocks are quite impressive for their size, features, and power consumption. Some of the other clocks we’ve featured recently include robot clocks, clocks for social good, and clocks that are not just clocks (but still won’t explode). We’re suckers for a good clock project here, so keep sending them in!

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Hackaday Prize Semifinalist: A Smart Battery Analyzer

[K.C. Lee]’s entry for the Hackaday Prize won’t cure cancer, wipe a disease from the planet, stop an alien invasion, or save the world. His battery charger and analyzer is, however, a useful little device for determining the charge and discharge characteristics of batteries, and can also be used as dual channel electronic load, current source, or power supply.

Inside [K.C.]’s device are all the tools required for charging and discharging lithium-ion, lead acid, and NiMH batteries. He’s doing this with a few slightly unusual circuits, including a SEPIC DC to DC converter, and an ‘analog’ PWM controller. these two techniques together mean [K.C.] can get away with smaller caps and inductors in his design, which also means less ripple on the output. As far as battery chargers and dischargers go, this one is very well designed.

Control of battery discharging and charging happens through a SILabs 8051-based microcontroller with USB. The UI is a simple Nokia LCD and an app running in Windows. If you want to save the world, this isn’t the project for you. If you need to test a few rechargeable batteries, this is a great device to have on the workbench.

The 2015 Hackaday Prize is sponsored by: