Home Brew Supercapacitor Whipped Up In The Kitchen

[Taavi] has a problem – a wonky alarm clock is causing him to repeatedly miss his chemistry class. His solution? Outfit his clock radio with a supercapacitor, of course! But not just any supercapacitor – a home-brew 400 Farad supercap in a Tic Tac container (YouTube video in Estonian with English subtitles.)

[Taavi] turns out to be quite a resourceful lad with his build. A bit of hardware cloth and some stainless steel from a scouring pad form a support for the porous carbon electrode, made by mixing crushed activated charcoal with epoxy and squeezing them in a field-expedient press. We’ll bet his roommates weren’t too keen with the way he harvested materials for the press from the kitchen table, nor were they likely thrilled with what he did to the coffee grinder, but science isn’t about the “why?”; it’s about the “why not?” Electrodes are sandwiched with a dielectric made from polypropylene shade cloth, squeezed into a Tic Tac container, and filled with drain cleaner for the electrolyte. A quick bit of charging circuitry, and [Taavi] doesn’t have to sweat that tardy slip anymore.

The video is part of a series of 111 chemistry lessons developed by the chemistry faculty of the University of Tartu in Estonia. The list of experiments is impressive, and a lot of the teaser stills show impressively exothermic reactions, like the reduction of lead oxide with aluminum to get metallic lead or what happens when rubidium and water get together. Some of this is serious “do not try this at home” stuff, but there’s no denying the appeal of watching stuff blow up.

As for [Taavi]’s supercap, we’ve seen a few applications for them before, like this hybrid scooter. [Taavi] may also want to earn points for Tic Tac hacks by pairing his supercapacitor with this Tic Tac clock.

[Thanks, Lloyd!]

Self Powered Camera Powers Itself

Cameras sense light to create images, and solar cells turn light into energy. Why not mash the two together and create a self-powered camera?

The Computer Vision Laboratory at Columbia built this unique camera, which harvests power from its photodiode sensors. These photodiodes also act as an array of pixels that can recover an image. The result is a black and white video camera that needs no external power supply.

The energy harvester circuit charges up a supercap that provides power to the system. The frame rate of the camera is limited by the energy that can be harvested: higher frame rates require more juice. For this reason, the team developed an algorithm that varies the frame rate based on available energy.

The MC13226V microcontroller that was used for this build features an internal 2.4 GHz radio. The group mentions wireless functionality as a possibility feature in the future, which would make for a completely untethered, battery free camera.

Replacing the Lead in a Motorcycle Battery with Supercaps

[Raphael] has a motorcycle he’s constantly working on, and for him that means replacing the battery occasionally. Tired of the lead-acid batteries that have been used for 100 years now, he took a look at some of the alternatives, namely lithium and the much cooler supercapacitor option. A trip to the local electronics distributor, and [Raphael] had a new supercapacitor battery for his bike, and hopefully he’ll never need to buy another chunk of lead again.

The battery pack is built from six 2.7V, 350F caps, a few connectors, and a handful of diodes. These are lashed together with rubber bands to form a 16V, 58F capacitor that makes for a great stand-in for a chunk of lead or a potentially puffy lithium battery.

[Raphael] put up a walkthrough video of his battery pack where he shows off the enclosure – an old, empty lead acid cell. He also goes through the back current protection and his method of balancing the supercaps with a few diodes.

Supercapacitors for the Raspberry Pi

As versatile as the Raspberry Pi is, it has a weakness when it needs to be able to shut down properly during a power outage, especially when handling data-sensitive or industrial applications. To solve this problem, [Pavol Sedlacek] has created a supercapacitor-based UPS specifically for the Raspberry Pi that gives it enough time to properly halt its processes and shut down if it detects a power failure.

The device is called the Juice4Halt. It uses a DC-DC converter to provide power to the Pi from the normal power supply and to charge the supercapacitors during normal operation. It is bidirectional, so in the event of a power failure it works in reverse to take power from the capacitors and feed it back to the Pi. A second DC-DC converter handles power from an external power supply.

A side effect of using supercapacitors as a UPS is that they can also help the Pi survive brownouts. The project site has an incredible amount of detail about the functionality of the device, including circuit diagrams and the source code. We’ve seen other supercapacitor-based UPS units before but this particular one is much more robust and would be truly at home in any industrial or other sensitive setting.

Hackaday Links: April 27, 2014



The HackFFM hackerspace in Frankfurt finally got their CO2 laser up and running, and the folks there were looking for something to engrave. They realized the labels on IC packages are commonly laser engraved, so they made a DIP-sized Arduino. The pins are labelled just as they would be on an Arduino, and a few SMD components dead bugged onto the pins provide all the required circuitry. Video here.

A few years ago, we heard [David Mellis] built a DIY cell phone for an MIT Media Lab thingy. Apparently it’s making the blog rounds again thanks to the Raspi cell phone we featured yesterday. Here’s the Arduino cell phone again. Honestly we’d prefer the minimalist DIY Nokia inspired version.

The Raspberry Pi is now a form factor, with the HummingBoard, a Freescale i.MX6-powered clone, being released soon. There’s another form factor compatible platform out there, the Banana Pi, and you can actually buy it now. It’s an ARM A20 dual core running at 1GHz, Gig of RAM, and Gigabit Ethernet for about $60. That SATA port is really, really cool, too.

[Richard] has been working on a solar-powered sun jar this winter and now he’s done. The design uses two small solar panels to charge up two 500F (!) supercapacitors. There’s a very cool and very small supercap charging circuit in there, and unless this thing is placed in a very dark closet, it’ll probably keep running forever. Or until something breaks.

Here’s something awesome for the synth heads out there: it’s an analog modeling synthesizer currently on Indiegogo. Three DCOs, 18dB lowpass filter, 2 envelopes and an LFO, for all that classic Moog, Oberheim, and Roland goodness. It’s also pretty cheap at $120 USD. We really don’t get enough synth and musical builds here at Hackaday, so if you’re working on something, send it in.

A glass-based PCB? Sure. Here’s [Masataka Joei] put gold and silver on a piece of glass, masked off a few decorative shapes, and sandblasted the excess electrum away. [Masataka] is using it for jewelery, but the mind races once you realize you could solder stuff to it.

Raspberry Pi UPS Using Supercapacitors

What happens when you want to integrate a Raspberry Pi into some kind of project that gets turned on and off with mains voltage? Do you power the Pi separately, or make a UPS for it?

[Lutz Lisseck] decided he wanted to turn his ambient-lamp (Rundbuntplasma) on and off with only the main power switch in his Hackerpsace. He could build a traditional UPS using a battery pack (it’s only 5V after all!) but decided to take it a step further. He picked up a pair of 50F supercapacitors. This way his UPS would last longer than his Pi would! The caps store just enough power that when the main supply is cut, a GPIO notices, tells the Pi, and it begins a shutdown sequence lasting about 30 seconds.

While [Lutz] is using two 2.7V supercapacitors, he mentions it would be a lot cheaper to use a step-up converter instead of putting them in series — but he had the caps on hand so decided to use both.

If you need it to last a bit longer, you could make one with rechargeable batteries…

Add-on panel brings automated vents flaps to a PC

[SXRguyinMA] built a replacement top bezel for his computer case. He wanted to add vents that would automatically open or close based on the cooling needs of the computer. With some careful measurements he modeled the parts in Sketchup and sent out for them to be cut from styrene with a water jet cutter. The parts came back looking great and the assembly of the shutters went swimmingly. The bezel also includes a lighted screen for temperature information, as well as the front USB ports, headphone and mic jacks, etc. Hidden underneath is an Arduino board and servo motor. The Arduino polls the temperature and drives the servo to adjust the fins accordingly. There’s even a supercap in the circuit that will close the vents when the PC powers down or when power is unexpectedly lost. See it in action after the break.

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