A betta fish swims in an MFC.

Microbial Fuel Cell With A Side Of Betta Fish

October 16, 2014 by 35 Comments

Move over, potato batteries: DIY microbial fuel cells are here to stay! A microbial fuel cell (MFC) is a device that uses bacteria in an anaerobic (oxygen-poor) environment to convert chemical energy into electricity. [drdan152] posted steps on how to make a soil-based MFC  with a neat twist: it’s also a fishbowl for a betta fish.

[drdan152] used soil from the wetlands, referred to as “muck.” This nutrient-rich soil provided a hearty supply of bacteria, especially Geobacter species, known for their uncanny ability to transport electrons outside their cells using bacterial nanowires. The proton exchange membrane (PEM) was made up of salt, water, and agar. After some initial runs, [drdan152] determined that flat char cloth made the best anode, while red copper wire served as the cathode. Assembling the MFC was as simple as surrounding the anode with a thick layer of muck on all sides, adding the PEM on top, followed by water. The cathode was situated halfway out of the water.

After a couple of days, the voltage increased in proportion to the amount of bacteria growing on the anode. The betta fish can happily live in this habitat for a short period of time(it still has to be fed, of course), and the bacteria certainly won’t mind – the fish’s excrement provides an additional food supply. As a bonus, the water is kept clean. However, like any aquarium, the water will need to be changed periodically as carbon dioxide byproduct accumulates from the fish’s respiration and the MFC (high carbon dioxide levels = dead betta fish).

The MFC generates 725 mV. [drdan152] is not satisfied with that number, and is testing out charge pump circuits to generate as much as 3V. We are looking forward to seeing the results. We also wonder if a small aquatic plant could help make it a more self-sustaining environment for the fish. In the meantime, [drdan152] is encouraging others to try larger-scale versions of this MFC. Perhaps MFC-powered carnivorous robots doubling as mobile aquariums are in our near future.

A breakdown of the various parts of the Game Tin

Game Tin: Handheld Games With No Batteries

October 16, 2014 by 54 Comments

Anyone who grew up with a Game Boy knows how well they sucked through AA batteries. [Nick]’s Game Tin console solves this problem by running of an ultracapacitor charged by solar power.

The console is based on a EFM32 microcontroller: an ARM device designed for low power applications. The 128×128 pixel monochrome memory display provides low-fi graphics while maintaining low power consumption.

There’s two solar cells and a BQ25570 energy harvesting IC to charge the ultracap. This chip takes care of maximum power point tracking to get the most out of the solar cells. If it’s dark out, the device can be charged in about 30 seconds by connecting USB power.

The 10 F Maxwell ultracapacitor can run a game on the device for 1.5 hours without sunlight, and the device runs indefinitely in the sun. Thanks to the memory display, applications that have lower refresh rates will have much lower power consumption.

The Game Tin is open source, and is being developed using KiCad. You can grab all the EDA files from Bitbucket. [Nick] is also gauging interest in the Game Tin, and hopes to release it as a kit.

Fail Of The Week: [Chris] Vs. The Gorn

October 16, 2014 by 30 Comments

This week, [Chris] tips the scales but ultimately fails. He’s on the road, hacking through the Great White North and improvising from a poorly-lit echo chamber that happens to have a vise.

Knowing nothing about firearms (do you believe that?), he decided to build a BB cannon out of pure scrap. Several kinds of sparks fly, starting with a Hitachi drill-as-lathe and ending with a tiny cupcake sparkler. [Chris] proceeds to bore out some redi-rod by eyeballing it and offers helpful tips for course correction should you attempt same. Having centered the cavity, he drills out a tiny hole for a fuse.

His first fuse is of the crushed up match head paste variety. It burns kind of slowly and does not launch the BB. Naturally, Plan B is to make napalm glue to adhere Pyrodex pistol powder to paper. As you might imagine, it worked quite well. The wadding was singed, but still no joy. After packing her full of propellant, it still didn’t explode and merely burned out the blowhole. So, what gives? Insufficient barrel length? Should have used bamboo instead of redi-rod? Didn’t want it badly enough? Give us your fodder below.

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Hackaday Munich — Get Your Ticket Now!

October 16, 2014 by 24 Comments

If you’re anywhere remotely near Munich in November you’re not going to want to miss this. Hackaday is throwing our first European event! The fun runs from 12:30-23:30 on Thursday, November 13th, 2014.

Take the afternoon off of work

Tell your boss this is professional development, then grab all your hacking gear and head on down to Technikum at the Munich Kultfabrik.

Our set of workshops will test your embedded skills whether you’re a beginner or seasoned veteran. These include controlling small robots, working with audio processing from a Moog synth, reverse engineering some mystery hardware, and trying your hand at machine vision.

Try win the afternoon’s challenges. Implement the fastest and most reliable robot brain, design the best Moog synth add-on circuit. Or prove your logic skills by coding a perfect Computer Vision game solver. We’ll bring some prizes for those that show the most clever and impressive skill.

Take in the talks and learn the winner of The Hackaday Prize

Beginning at 19:00 we present a couple of talks about embedded hardware sure to impress the most discerning of hackers. Immediately following we will announce the Grand Prize winner of the 2014 Hackaday Prize. This Open Hardware build is the project that made it through more than 800 entries to secure a trip into space and eternal recognition from the Hackaday community.

Finish the day with a party

Finally, we’ll dim the lights and turn up the music for The Hackaday Prize Party. Enjoy some food and beverages, get yourself 3D scanned, try your hand at some vintage video games, and enjoy the company of the Hackaday Community. In attendance will be [Mike Szczys], [Brian Benchoff], [Aleksandar Bradic], [Jasmine Brackett], and [Ben Delarre].

We’ll see you there!

Robotic Terminator Teddy Will Protect You While You Sleep

October 16, 2014 by 13 Comments

This animatronic teddy bear is the stuff of nightmares… or dreams if you’re into mutant robot toys. In either case, this project by [Erwin Ried] is charming and creepy, as he gives life to an unassuming stuffed animal by implanting it with motorized parts.

[Erwin] achieves several degrees of motion throughout the bear’s body by filling the skin with a series of 3D printed bones, conjoined by servo motors at its shoulders, elbows and neck. The motors are controlled via an Arduino running slave to a custom application written in C#. This application uses the motion tracking and facial recognition features of the Xbox Kinect, mapping the input from the puppeteer’s movement to the motors of the doll’s skeleton. Additionally, two red LEDs illuminate under the bear’s cheeks in response to the facial expression of the person controlling it, as an additional reminder that teddy feels what you feel.

bearSkeleton

In [Erwin’s] video, he demonstrates what his application sees through the Kinect’s camera side-by-side with the mechanical skeleton its controlling. The finished product isn’t something I’d soon cuddle up to at night, but looks amazing and is fun to watch in action :

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Goldilocks Climate Box Keeps Lager Fermentation Environment Just Right

October 15, 2014 by 8 Comments

September was warmish in many places around the world including [Ole]’s native Denmark. But that did not stop him from brewing lager flavored with plums from his own garden, and neither did his indifference to lagers in general.

Lager fermentation requires a consistent, low temperature. While many homebrewers might modify an electric refrigerator, [Ole] wasn’t interested in the cost of running a second one just for brewing beer. Instead, he built a climate box to work with the cool temperature in his garage. Starting with scrap wood from other projects, he lined the walls with polystyrene and put a layer of wood on the floor to help support the fermentation bucket.

Maintaining a consistent temperature in the box called for both heating and cooling. He pulled the Peltier from a 12V cooler meant to run off a car’s cigarette lighter, and used a spare ceramic heater that was lying around in case his primary reptile warmer went on the fritz.

An Arduino and a custom shield drive separate PID controllers for the Peltier and the heater. The shield has a temperature probe, and he extended the USB outside the climate box so the PIDs can be adjusted without disturbing the inside temperature. The schematic, board file, and code are all available in a zip you can get from his post.

The Peltier couldn’t quite compensate for the overly warm weather and the heat caused by the fermentation, but it was stable enough to produce a nice, plum-flavored lager he has dubbed Lektor Blom­mes malt­bol­che, which is a triple Danish pun he explains in the write-up.

Palatable Pallet Procurement Procedures

October 15, 2014 by 14 Comments

Wooden pallets are a versatile and widely-available starting point for a multitude of projects. Best of all, they can usually be acquired free of charge. But choose the wrong kind of pallet and you could end up paying dearly. [Eric] has compiled a great deal of useful information about pallets that will help you find ideal candidates and prepare them for whatever project you have in mind, be it a coffee table or a backyard roller coaster.

Pallets come in several styles and loader configurations. Some are made with space between the boards, and others are closed. If you take nothing else away from his article, just remember to look for plain, untinted pallets with no markings and you’ll be fine.

No markings means the pallet was used domestically, so markings aren’t required. Marked pallets from abroad should feature the IPPC logo as well as a treatment code indicating the method used on the material. Debarked (DB), heat treated (HT), and pallets with the European Pallet Association logo (EPAL) are all safe choices. Pallets labeled (MB) were treated with methyl bromide, which is a poisonous fungicide. Colored pallets should be avoided as well. If you find one in a cool color, take a picture of it and find some paint in a similar hue.

Safe pallets can be had from many places ranging from hardware stores to feed and tack supply stores. Find someone you can ask for permission to take pallets—they might even help you load them. Keep some gloves in your trunk to avoid splinters.