Open-Source Water Quality Tester

Open-Source Water Quality Tester

Contaminated water is a huge problem in many third-world countries. Impure water leads to many serious health problems, especially in children. Installing a water purification system seems like a simple solution to this problem, but choosing the right purification system depends on the level of contaminants in the water.

Water turbidity testers are often used to measure the severity of water contamination. Unfortunately most commercial water turbidity testers are very expensive, so [Wijnen, Anzalone, and Pearce] set out to develop a much more affordable open-source tester. Their tester performs just as well as commercial units, but costs 7-15 times less.

The open-source water tester was designed in OpenSCAD and 3d printed. It houses an Arduino with a custom shield that measures the frequency from several TSL235R light-to-frequency converters. An LED illuminates the water and the sensors measure how much light is diffused and reflected off of particles in the water. Another sensor measures the brightness of the LED as a baseline reference. The turbidity of the water is calculated from the brightness values, and is displayed on a character LCD. More details about the tester are included in a fairly extensive paper.

[Thanks Andrew]

Microbial Fuel Cell with a Side of Betta Fish

A betta fish swims in an MFC.

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.

The Joys Of Shipping From China

Trucks A few months ago, news of a new PCB fab service headed up by [Ian] over at Dangerous Prototypes leaked onto the Internet. It’s extremely cheap – $14 USD for a 5cm square board with free worldwide shipping. [Ian] admits the boards aren’t the greatest quality, that’s not the point; the site’s motto is simply, ‘No bull, just crappy PCBs.’

What began as an internal website to handle all of DP’s PCB orders was now on the Internet, and orders were flying in. At first, shipping a few dozen PCBs around the globe every week was easy, but since Dirty PCBs hit the big time, customers rightfully or not, started freaking out because of the oddities of Chinese shipping and logistics companies.

[Ian] is using Espeed Post for all their shipping, and if you’ve ever ordered anything from China off of Ebay, it’s possible you’ve had something shipped through Espeed before. Because of the oddities of shipping, and the fact that Shenzhen and Hong Kong are right next to each other, even the people at Dangerous Prototypes don’t know which countries your PCBs will go through on the trip from the fab house to your front door. This has caused much consternation with DirtyPCB customers that don’t seem to realize they’re getting custom PCBs for under two dollars a board, shipped to them across the world in a week for free. Some people’s children, huh?

Things get significantly, ahem, dirtier, when Chinese holidays are taken into account. China has a lot of them, and they’re long. They’re just wrapping up the National Day holiday, 10 days in the first week of October. Everyone is backlogged, and the China/Hong Kong border is the mess of trucks seen above.

If a holiday isn’t bad enough, the new President of China is cracking down on corruption. 500 officials were fired at the largest land border with Hong Kong, due in no small part to vans full of meth and tons of counterfeit currency. Every package leaving China is inspected individually, and shipping times have exploded.

To deal with this, Dangerous Prototypes has posted a big red warning on the dirtypcb site, but experience in dealing with people on the Internet tells them this won’t be a viable solution. They’re now dealing directly with DHL, and are apparently getting priority clearance through customs. It’s not fun, as DP will now have to figure out how to work with DHL’s API. It’s a lot of work and a lot of trouble, but DP still has a few tricks up their sleeve – they’re working on an online schematic entry and PCB layout site and the extremely interesting DirtyCables – custom cables shipped to your door.

Remote Control for an Elevator


The elevator at [Alex]‘s office building has some quirks which make it very inconvenient to everyone in the building. The major problem was that the doors of the elevator at each floor stay locked until someone walks down the hall to hit a button. Obviously this was a hassle, so [Alex] built a controller that can remotely call and unlock the elevator. (Part 2 of the project is located on a separate page.)

The first step was to source the hardware and figure out exactly how the controls for the elevator worked. [Alex] decided to use an Electric Imp for this project, and after getting it connected to the Internet, he realized that he could power it directly off of the elevator’s 10V supply. From there, he used relays to interface the Electric Imp with the “elevator call” and “elevator unlock” buttons inside the elevator’s control panel.

Once the hardware side was completed, it was time to move on to the software side. [Alex] wrote a mobile app for a user interface that can be accessed from anywhere, and also wrote the code for the Electric Imp agent and the code that runs on the Electric Imp itself. Now, a simple tap of a button on a mobile device is enough to call the elevator or unlock it, rather than in the past where someone had to run down a hall to hit the button.

We hope there is some security on the mobile app, otherwise anyone in the world will be able to call the elevator and turn it into a passenger-less useless machine!

TwoBitCircus: The Business of Building Interactive Entertainment


The Hackaday 10th anniversary was an awful lot of fun, and part of what made it awesome was all the cool things that the community brought to the event. We hadn’t really had a chance to get down to meet the guys from TwoBitCircus before now but they were more than happy to bring along their excellent Hexacade machine. The 6-player custom built arcade game that was an absolute blast!

After the party TwoBitCircus’ fearless leaders [Brent Bushnell] and [Eric Gradman] invited us over to their space for a quick look at their workshop, and to give us a personal invite to the Hacker Preview day for their upcoming STEAM Carnival. No this isn’t Steam as in Steam-punk, but STEAM as in Science Technology Engineering Art and Mathematics.

TwoBitCircus Workshop

Their space is really quite amazing, part of The Brewery Art Colony near downton Los Angeles. The building is actually an old steam power plant with incredibly high ceilings. The TwoBitCircus crew is now about 30 people all building interactive games and art pieces for events. They call themselves a digital circus and a lot of their work harkens back to old carnival games of yore with a new digital twist.

[Eric] and [Brent] spared a few minutes to give us a quick run down of what sort of games to expect at the STEAM Carnival. There will be a wide array of entertainment: giant marble runs controlled by see-saws, whack-a-mole/twister mashups on huge glowing button walls, laser based foosball, and the more extreme immolation dunk tank! It will be a most entertaining and educational event. The main public days are on the weekend of 25th – 26th of October, but there is an invite only hacker preview for the local community on Thursday October 23rd which we will be attending. If you’d like to go to the main event, use the code HACKADAY for $5 off the ticket price of $25.

What was most interesting about TwoBitCircus for me as a maker of things was how these guys have turned their hobby into a thriving events business. Brent tells us that they’ve been at this for 8 years now and the company has been around for 3. They’re doing pretty well too, making incredible things for some of the biggest companies around. This really is the best possible job for any inventive hacker sort, building crazy stuff all day for people to play with! I left the place feeling incredibly envious.

Check out the photos below for some impression of the sort of craziness you might see at the carnival!

[Read more...]

Writing a Message in Hypnotizing Style


If you’ve ever encountered a rapidly spinning split-flap displays at an airport terminal, it’s hard not to stop and marvel at them in action for a few extra seconds. Because of this same fascination, [M1k3y] began restoring an old one-hundred and twenty character sign, which he outlines the process of on his blog.

Finding documentation on this old relic turned out to be an impossibility; the producers of the model themselves didn’t even keep it off-hand any longer. In spite of that, [M1k3y] was able to determine the function of the small amount of circuitry driving the sign through process of elimination by studying the components. After nearly a year of poking at it, he happened across a video by the Trollhöhle Compute Club, demonstrating the successful use of the same display model. Luckily, they were kind enough to share their working source code. By reverse engineering the serial protocol in their example, he was able to write his own software to get the sign moving at last.

Once up and running, [M1k3y] learned that only eighty of the sign’s characters were still operable, but that is plenty to make a mesmerizing statement! Here is a video of the cycling letters in action:

[Read more...]

Ghost Gunner Machines Your AR-15


Defense Distributed and founder [Cody Wilson] have released Ghost Gunner. Defense Distributed entered the public eye a couple of years ago with The Liberator, the world’s first 3D printed gun. Since anyone with a 3D printer can print a Liberator, it is effectively untraceable. This raised a lot of questions in the media and public eye.

Ghost Gunner is a variation on the untraceable theme. Essentially, Ghost Gunner is a CNC designed for one purpose: final drilling and milling steps for AR-15 lower receivers. The reason for this has to do with federal gun laws in the United States. According to US law, the lower receiver is the actual firearm, and is regulated. But when does a block of aluminum become a lower receiver? Here, US law states that the metal becomes a regulated receiver when the machining operations are more than 80% complete.

ghostgunnergunAnyone can legally buy a barrel, trigger, stock, upper receiver, and various other parts to build an AR-15. To complete the weapon, they only need to buy an 80% lower receiver and perform the last 20% of the metal work. This work can be performed with everything from a drill press to a milling machine to hand tools. Ghost Gunner partially automates this process, making it easier and faster to complete lower receivers and build weapons.

Defense Distributed calls Ghost Gunner an open source hardware project, though we were unable to find the files available for download at this time. It appears that the slides are made up of MakerSlide or a similar aluminum extrusion. The steppers appear to be standard Nema 17 size.

Defense Distributed says that they’ve been having a hard time keeping up with the Ghost Gunner pre-orders. At $1300 each though, we think a general purpose mill or small CNC would be a better deal.

[Read more...]


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