Hackaday Prize Entry: An Oven Of Raspberry Pis

When the Raspberry Pi was introduced, the world was given a very cheap, usable Linux computer. Cheap is good, and it enables one kind of project that was previously fairly expensive. This, of course, is cluster computing, and now we can imagine an Aronofsky-esque Beowulf cluster in our apartment.

This Hackaday Prize entry is for a 100-board cluster of Raspberry Pis running Hadoop. Has something like this been done before? Most certainly. The trick is getting it right, being able to physically scale the cluster, and putting the right software on it.

The Raspberry Pi doesn’t have connectors in all the right places. The Ethernet and USB is on one side, power input is on another, and god help you if you need a direct serial connection to a Pi in the middle of a stack. This is the physical problem of putting a cluster of Pis together. If you’re exceptionally clever and are using Pi Zeros, you’ll come up with something like this, but for normal Pis, you’ll need an enclosure, a beefy, efficient power supply, and a mess of network switches.

For the software, the team behind this box of Raspberries is turning to Hadoop. Yahoo recently built a Hadoop cluster with 32,000 nodes used for deep learning and other very computationally intensive tasks. This much smaller cluster won’t be used for very demanding work. Instead, this cluster will be used for education, training, and training those ever important STEAM students. It’s big data in a small package, and a great project for the Hackaday Prize.

Retrofitted Retro Radio

In a world full of products that are only used for a brief time and then discarded, it gives a lot of us solace to know that there was a time when furniture was made out of solid wood and not particle board, or when coffee makers were made out of metal and not plastic. It’s hard to say exactly what precipitated the change to our one-time-use culture, but in the meantime there are projects that serve to re-purpose those old, durable products from another time so that they can stay relevant in today’s ever-changing world. [Jose]’s new old radio is a great example of this style of hack.

[Jose] had a 1970s-era single-speaker radio that he found in a thrift store. The first thought that he had to get the aesthetically pleasing radio working again was to install a Bluetooth receiver into the radio’s amplifier. This proved to be too time-consuming of a task, and [Jose] decided to drive the Bluetooth module off of the power circuit for the light bulb. He built a 6V AC to 4.2V DC circuit, swapped over the speaker cable, and started listening to his tunes. The modifications he made aren’t destructive, either. If he wants, he will be able to reconnect the original (and still functional) circuitry back to the speaker and pretend he’s back in 1970.

While this isn’t the most intricate hack we’ve ever featured, it’s always refreshing to see someone get use out of an old piece of technology rather than send it off to the landfill with all of our Pentium IIs or last year’s IKEA shelves that have already fallen apart. And even if the 70s aren’t your era of choice, perhaps something newer will inspire you to bust a move.

The Quest for Mice With Frickin’ Laser Beams (Pointed At Their Brains), Building A Laser Controller

The logo for the field is kind of cute though.
The logo for the field is kind of cute though.

[Scott Harden] is working on a research project involving optogenetics. From what we were able to piece together optogenetics is like this: someone genetically modifies a mouse to have cell behaviors which can activated by light sensitive proteins. The mice then have a frikin’ lasers mounted on their heads, but pointing inwards towards their brains not out towards Mr. Bond’s.

Naturally, to make any guesses about the resulting output behavior from the mouse the input light has to be very controlled and exact. [Scott] had a laser and he had a driver, but he didn’t have a controller to fire the pulses. To make things more difficult, the research was already underway and the controller had to be built

The expensive laser driver had a bizarre output of maybe positive 28 volts or, perhaps, negative 28 volts… at eight amps. It was an industry standard in a very small industry. He didn’t have a really good way to measure or verify this without either destroying his measuring equipment or the laser driver. So he decided to just build a voltage-agnostic input on his controller. As a bonus the opto-isolated input would protect the expensive controller.

The kind of travesty that can occur when [Stefan Kiese] doesn't have access to nice project boxes.
The kind of travesty that can occur when [Scott] doesn’t have access to nice project boxes.
The output is handled by an ATtiny85. He admits that a 555 circuit could generate the signal he needed, but to get a precision pulse it was easier to just hook up a microcontroller to a crystal and know that it’s 100% correct. Otherwise he’d have to spend all day with an oscilloscope fiddling with potentiometers. Only a few Hackaday readers relish the thought as a relaxing Sunday afternoon.

He packaged everything in a nice project box. He keeps them on hand to prevent him from building circuits on whatever he can find. Adding some tricks from the ham-radio hobby made the box look very professional. He was pleased and surprised to find that the box worked on his first try.

A Trove Of 3D Printer Filament Test Data

We’re not sure what a typical weekend at [Walter]’s house is like, but we can probably safely assume that any activity taking place is at minimum accompanied by the hum of a 3D printer somewhere in the background.

Those of us who 3D print have had our experiences with bad rolls of filament. Anything from filament that warps when it shouldn’t to actual wood splinters mixed in somewhere in the manufacturing process clogging up our nozzles. There are lots of workarounds, but the best one is to not buy bad filament in the first place. To this end [Walter] has spent many hours cataloging the results of the different filaments that have made it through his shop.

We really enjoyed his comparison of twleve different yellow filaments printed side by side with the same settings on the same printer. You can really see the difference high dimensional tolerance, the right colorant mix, and good virgin plastic stock makes to the quality of the final print. Also, how transparent different brands of transparent actually are as well as the weight of spools from different brands (So you can weigh your spool to see how much is left).

The part we really liked was his list every filament he’s experienced in: PLA, ABS, PETG, Flexible, Nylon, Metal, Wood, and Other. This was a massive effort, and while his review is naturally subjective, it’s still nice to have someone else’s experience to rely on when figuring out where to spend your next thirty dollars.

Hacklet 120 – Coffee Hacks

Hackers need fuel to hack. In general that fuel comes in the form of food, water, and caffeine. Not necessarily in that order. While soda or energy drinks will do in a pinch, the best hackers know that the purest form of caffeine comes from coffee. This of course means that there have been decades of coffee hacks. The first Internet-connected coffee pot dates all way back to 1991, before the web even had pictures. We’ve come a long way since then. This week on the Hacklet we’re checking out some of the best coffee hacks on Hackaday.io!

coffee1We start with [opeRaptor] and CoffeeOfThings. [OpeRaptor] has created a wireless, internet connected coffee carafe. The carafe has three CdS cells which enable it to detect how much black gold is left in the pot. A TMP36 sensor reports the current coffee temperature. Data is sent out via a NRF24l01 radio. The brains of the coffee pot is an MSP430 microcontroller. All this runs from a simple CR2032 coin cell. A base station receives the coffee data, displays it on a very nice Vacuum fluorescent Display (VFD). An ESP8266 then passes the data on to the internet.

 

coffewarmerNext up is [magnustron] with quad-386 coffee heater. No one likes a cold cup of coffee. Everyone loves old CPUs. [Magnustron] turned these two shower thoughts into a the world’s first USB powered quad CPU coffee warmer with data logging capabilities. A simple ATtiny461 micro runs the show. PC connectivity is via USB using the V-USB library. [Magnustron] has gotten the CPUs to warm up, but is having some issues with switching. them on. Turning all four heaters on too quickly causes the rail to droop, leading to dropped USB connections. Those power-hungry 386 chips may be a bit too much for a single USB connection. It might be time to add an external power supply.

groundsNext is [kesh1030] with Using Waste Coffee As A Biodiesel Source. Coffee isn’t just liquid energy. There’s oil in them there grounds. Millions of pounds of used coffee grounds produced every year can be converted to biodiesel fuel. [Kesh1030] experimented with different coffee grounds, and different ways to prepare them. The oil was extracted from the coffee using hexane, which is a bit of a nasty solvent. [Kesh1030] used a fume hood to stay safe. He found that homogenized coffee grounds had an 11.87% oil yield. Used homogenized coffee grounds weren’t far behind, with 9.82% yield of oil. Nearly 10% per weight yield isn’t too shabby, considering this is all going into the trash.

dripperFinally, we have [saadcaffeine] with Caffeinator: gravity powered geek fuel dripper. This is a project of few words, but the images tell much of the story. [Saadcaffeine] created his own cold drip iced coffee maker using upcycled and found components. Three clothes hangers form an ingenious tripod. The tripod holds two soda bottles – the water reservoir and the brew pot. Water is restricted by small holes in the soda bottle caps. This allows it to drop slowly though the machine, giving it time to soak up all the caffeinated goodness. The result is a fresh cup of cold drip. Just add ice and enjoy a quick power up!

If you want to see more coffee hacks, check out our new coffee projects list. See a project I might have missed? Don’t be shy, just drop me a message on Hackaday.io. That’s it for this week’s Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Hackerspacing: Making A Temperature Logger

The folks at Swindon Makerspace took possession of a new space a few months ago after a long time in temporary accommodation. They’ve made impressive progress making it their own, and are the envy of their neighbours.

A small part of the new space is a temperature logger, and it’s one whose construction they’ve detailed on their website. It’s a simple piece of hardware based around a Dallas DS18B20 1-wire temperature sensor and an ESP8266 module, powered by 3 AA batteries and passing its data to data.sparkfun.com. The PCB was created using the space’s CNC router, and the surface-mount components were hand-soldered. The whole thing is dwarfed by its battery box, and will eventually be housed in its own 3D printed case. Sadly they’ve not posted the files, though it’s a simple enough circuit that’s widely used, it looks similar to this one with the addition of a voltage regulator.

The device itself isn’t really the point here though, instead it serves here to highlight the role of a typical small hackspace in bringing simple custom electronic and other prototyping services to the grass roots of our community. Large city hackspaces with hundreds of members will have had the resources to create the space program of a small country for years, but makers in provincial towns like Swindon – even with their strong engineering heritage – have faced an uphill struggle to accumulate the members and resources to get under way.

So to the wider world it’s a simple temperature logger but it really represents more than that — another town now has a thriving and sustainable makerspace. Could your town do the same?

If you’ve never used a Dallas 1-wire temperature sensor like the one the Swindon folks have in their logger, we suggest you read our primer on the parts and their protocol.

We’re Fans of Dave’s Fans

Hackaday.io contributor extraordinaire [davedarko] gets hot in the summer. We all do. But what separates him from the casual hacker is that he beat the heat by ordering four 120 mm case fans. He then 3D printed a minimalistic tower frame for the fans, and tied them all together with a ULN2004 and an ESP8266. The whole thing is controlled over the network via MQTT. That’s dedication to staying cool.

We really like the aesthetics of this design. A fan made up of fans! But from personal experience, we also know that these large case fans can push a lot of air fairly quietly. That’s important if you’re going to stand something like this up on your desk. While we’re not sure that a desk fan really needs networked individual PWM speed control, we can see the temptation.

Now that they’re individually controlled, nothing stops [davedarko] from turning this into a musical instrument, or even using the fans to transmit data. The only thing we wouldn’t do, despite the temptation to stick our fingers in the blades, is to complicate the design visually. Maybe that would finally teach the cat not to walk around on our desk.