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If You See Anything, Say Something? Math on a Plane

อังคาร, 05/10/2016 - 01:31

Remember September 2016 2015? That was the month that [Ahmed Mohamed] brought a modified clock to school and was accused of being a terrorist. The event divided people with some feeling like it was ignorance on the part of the school, some felt the school had to be cautious, some felt it was racial profiling, and others thought it was a deliberate provocation from his possibly politically active parents. In the end, [Ahmed] moved to Qatar.

Regardless of the truth behind the affair, this month we’ve seen something that is probably even less ambiguous. The Washington Post reports that a woman told an Air Wisconsin crew that she was too ill to fly. In reality, she was sitting next to a suspicious man and her illness was a ruse to report him to the crew.

Authorities questioned the man. What was his suspicious activity? Was he assembling a bomb? Carrying a weapon? Murmuring plans for destruction into a cell phone? No, he was writing math equations. University of Pennsylvania economics professor [Guido Menzio] was on his way to deliver a speech and was reviewing some differential equations related to his work.

[Menzio] says he was treated well, and the flight was only delayed two hours (which sounds better in a blog post then it does when you are flying). However, this–to me–highlights a very troubling indicator of the general public’s level of education about… well… everything. It is all too easy to imagine any Hackaday reader looking at a schematic or a hex dump or source code could have the same experience.

Some media has tried to tie the event to [Menzio’s] appearance (he’s Italian) but I was frankly surprised that someone would be afraid of an equation. The pen may be mightier than the sword, but a math equation won’t (by itself) down an aircraft. I’ve heard speculation that the woman might have thought the equations were Arabic. First of all, what? And secondly, what if it were? If a person is writing in Arabic on an airplane, that shouldn’t be cause for alarm.

It sounds like the airline (which is owned by American Airlines) and officials acted pretty reasonably if you took the threat as credible. The real problem is that the woman–and apparently, the pilot–either didn’t recognize the writing as equations or somehow feared equations?

Regardless of your personal feelings about the clock incident, you could at least make the argument that the school had a duty to act with caution. If they missed a real bomb, they would be highly criticized for not taking a threat seriously. However, it is hard to imagine how symbols on a piece of paper could be dangerous.

While the mainstream media will continue to focus on what this means for passenger safety and racial profiling, I see it as a barometer of the general public’s perception of science, math, and technology as dark arts.

Filed under: rants

Minimal MQTT: Building a Broker

อังคาร, 05/10/2016 - 00:01

In this short series, we’re going to get you set up with a completely DIY home automation system using MQTT. Why? Because it’s just about the easiest thing under the sun, and it’s something that many of you out there will be able to do with material on-hand: a Raspberry Pi as a server and an ESP8266 node as a sensor client. Expanding out to something more complicated is left as an exercise to the motivated reader, or can be simply left to mission creep.

We’ll do this in four baby steps. Each one should take you only fifteen minutes and is completely self-contained. There’s a bunch more that you can learn and explore, but we’re going to get you a taste of the power with the absolute minimal hassle.

In this installment, we’re going to build a broker on a Raspberry Pi, which is the hub of your MQTT network. Next time, we’ll get an ESP8266 up and running and start logging some data. After that, we’ll do some back-end scripting in Python to make the data speak, and in the last installment, we’ll explore some of the useful frills and fancy bits. Let’s get started!


MQTT is a pub-sub, store-and-forward, IoT-enabled, machine-to-machine connectivity protocol juggernaut. As you can see, it’s fully buzzword-compliant. That doesn’t necessarily mean that it’s super complicated, though. You can read up on MQTT until you’re blue in the face. Here’s the bare minimum you need to know to be comfortable.

The network has clients (called “clients”) and servers (called “brokers”). Clients, whether it’s your temperature sensor node or the graphing application that’s going to use the data, use the broker as a central hub. Data are arranged in “topics”, which use a directory-like structure. So the temperature node in my bedroom is called “home/bedroom/temp”. When I add a light sensor to my bedroom node, I’ll set up a topic called “home/bedroom/light” and so on.

When a client gets some new data, it “publishes” it to the topic — sends the data to the server. The server then forwards the data along to all of the other clients that have “subscribed” to the topic. In my example, the bedroom node publishes to “home/bedroom/temp” and then a databasing program which is a subscriber to “home/bedroom/temp” automatically receives it. And so does any other client that’s subscribed to the topic.
Often a given physical device will subscribe to some topics and publish to others.  My heating controller will want to act on the temperature sensors, and display its status on an LED in the bedroom, for instance. There’s naturally more to say, but let’s get our broker up and running first and explore the details later.

Build a Broker

OK, “build” is a little bit overstated. We’re just going to download mosquitto, which is the most widely-used broker. If you’ve got a Raspberry Pi (or other spare computer) lying around, you’ve got an MQTT broker-in-waiting. Unfortunately, Raspbian comes with an old version of mosquitto by default, so we’ll have to do a tiny bit more typing to get the most recent version. Here’s how I set up a fully-featured MQTT broker on a brand-new Raspberry Pi (Jessie Lite):

curl -O http://repo.mosquitto.org/debian/mosquitto-repo.gpg.key sudo apt-key add mosquitto-repo.gpg.key rm mosquitto-repo.gpg.key cd /etc/apt/sources.list.d/ sudo curl -O http://repo.mosquitto.org/debian/mosquitto-jessie.list sudo apt-get update sudo apt-get install mosquitto mosquitto-clients

Et voilà. Later, when we need to access the broker from the outside world, we’ll need to know the Raspberry Pi’s IP address, but that’s it. You’re up and running. If you’re using an older version of Raspbian, substitute “wheezy” for “jessie” in the fifth line. If you’re using anything other than a Raspberry Pi, you can probably find what you need, including Windows binaries, here. (I haven’t tested Windows or Mac.)

Playing Around

Now that our broker is set, let’s do some quick experiments to get a taste of how MQTT works in practice. The astute among you noticed that I also installed mosquitto-clients. Let’s try them out.

Open up a window and type mosquitto_sub -h localhost -t "test/topic". Congratulations, you’ve just subscribed a client to the “test/topic” topic. -h localhost connects you to an MQTT server on the local machine, rather than on the broader Internet. If we weren’t setting up our own server, I’d have you point to the MQTT test servers. As it is, I’ll just let you know that they’re out there when you need them.

OK, let’s publish our first data. Open up another window and type mosquitto_pub -h localhost -t "test/topic" -m "hello!" Same server, same topic, but now we’re sending a message. You should see the message pop up instantly in the subscribed window.

Try opening up multiple subscriber windows, subscribed to the same topic. You’ll see that they all get the message. Try sending messages to topics that don’t exist yet. What happens?

One last stupid MQTT trick before we get to the important stuff. MQTT can use two different types of wildcards in the topic names. So my network has “home/bedroom/temp” and “home/cellar/temp” topics. I can read all the temperatures by subscribing to “home/+/temp” and get all the values from my bedroom node from “home/bedroom/#”. (“+” matches one hierarchical level, while “#” stands for everything deeper in the tree.) Once you start using wildcards, you’ll want to know which topic is reporting, so try subscribing in verbose mode mosquitto_sub -h localhost -v -t "test/#" and send yourself some test messages to different topics.

Quality of Service

Here is MQTT’s killer feature for a low-power home automation sensor network: it’s a “store and forward” protocol with a couple levels of quality of service (QOS) guarantees. If your node has already registered with the broker and it’s offline when a new message comes in, the broker can take care of delivering that message to the node as soon as it reconnects. This means that your nodes can spend most of their lives in a deep sleep, conserving battery power, and when they do finally connect, they haven’t missed anything.

Three things are needed for the QOS feature: the subscribing clients need to be previously registered by ID with the server, and they need to disable the (default) clean-slate behavior otherwise all stored messages are erased when you log back in. Both the subscriber and the publisher need to be using quality-of-service level one or two so that the server knows it’s a stored message. (QOS level one usually suffices, but feel free to read up.)

Here’s an example:

subscriber: mosquitto_sub -h localhost -v -t "test/#" -c -q 1 -i "james bond" publisher: mosquitto_pub -h localhost -t "test/topic" -m "wowie" -q 1 mosquitto_pub -h localhost -t "test/topic" -m "zowie"

To demonstrate what QOS does, run the subscriber’s command in one window and send the other two messages to it. You’ll get them both. Now stop the subscriber with ctrl-c and resend both messages. Now, when you subscribe again, you’ll only get “wowie” because it was the message sent with QOS enabled.

One gotcha with IDs is that you’ll only get whatever has happened between IDed logins. You have to be previously registered with the server so that it saves messages for you. You can’t just walk in, give it a new ID, and say “what have I missed?” because it doesn’t know you yet.

Also note that the subscriber must do three things to enable receiving messages with QOS. The ID and QOS levels are obvious. The one I always forget is to disable clean-slate logins with the -c flag. Don’t forget.

Retained Messages

If you don’t need to get the full history of messages since your node was last online, consider the “retain” flag. When messages are sent as retained, the last such message gets automatically transmitted to any client that subscribes to the topic. Retained messages are great for things like status reports. Any time that you want to log in and see just the last value without having to wait for an update, you’ll wish you had retain set. And note that retained messages and QOS aren’t exclusive — just be careful because you’ll get one message (the most recent one) delivered twice.


This was just a taste of the power of having your own MQTT server running. Next, we’ll connect some small devices to the network, and then we’ll build up some back-end processing. If you’ve gotten this far and just can’t wait, try playing around with mosquitto_sub -h test.mosquitto.org -t "hackaday/new_articles" -c -q 1 -i "your_name_here". The stream is published with QOS=1 and retains the last message. Feel free to play around and show us what you build in the comments.

Filed under: Engineering, Hackaday Columns, Network Hacks, Original Art

3D Printing Bone

จันทร์, 05/09/2016 - 22:31

What do you print with your 3D printer? Key chains? More printer parts (our favorite)? Enclosures for PC boards? At Johns Hopkins, they want to print bones. Not Halloween skeletons, either. Actual bones for use in bodies.

According to Johns Hopkins, over 200,000 people a year need head or face bone replacements due to birth defects, trauma, or surgery. Traditionally, surgeons cut part of your leg bone that doesn’t bear much weight out and shape it to meet the patient’s need. However, this has a few problems. The cut in the leg isn’t pleasant. In addition, it is difficult to create subtle curved shapes for a face out of a relatively straight leg bone.

This is an obvious application for 3D printing if you could find a suitable material to produce faux bones. The FDA allows polycaprolactate (PCL) plastic for other clinical uses and it is attractive because it has a relatively low melting point. That’s important because mixing in biological additives is difficult to do at high temperatures.

Additives are important because a bone graft isn’t just a mechanical part. The plastic graft has to allow for live bone cells to attach to the new part. Researchers found that adding some powdered cow bone into the plastic made the resulting graft much more effective.

The tests were conducted on mice and determined the properties of bone grafts made with different percentages of bone power. Future grafts will likely use human bone powder, which is already used clinically in other situations.

We’ve seen soft tissue printed before. You can even print some bio material with an old inkjet.

Filed under: 3d Printer hacks, Medical hacks, news

The Coming Wide-Spread Use of Drones in Agriculture

จันทร์, 05/09/2016 - 21:01

Whether you call them UAVs (Unmanned Aerial Vehicles), UAS (Unmanned Aerial System), Drones, or something less polite – people are more familiar than ever with them. We’ll call them drones, and we’re not talking about the remote-controlled toy kind – we’re talking about the flying robot kind. They have sensors (GPS and more), can be given a Flight Plan (instructions on where to go), and can follow that plan autonomously while carrying out other instructions – no human pilot required. Many high-end tractors are already in service with this kind of automation and we’ve even seen automated harvesting assistance. But flying drones are small and they don’t plant seeds or pull weeds, so what exactly do they have to do with agriculture?

There are certain things that drones are very good at, and there are things in agriculture that are important but troublesome to do or get. Some of these things overlap, and in those spaces is where a budding industry has arisen.

Let’s cover what drones can offer and what growers can use, then dig into what is out there and happening over some fields right now.

These Things are Important to Farmers, but are Limited or Troublesome
  • Confirmation: Verifying that plants are growing where and when they should, and checking this as early and often as possible.
  • Early Detection of Problems: Detecting areas of poor growth and crop damage as early as possible, limiting impact and maximizing the chances of doing something about it.
  • Fertilizer Planning: A crop will never grow completely evenly, and choosing where to put fertilizer and how much to use based on plant density and health (instead of spreading it uniformly) can save significant money. This is called Variable Rate Application and anything that helps it get done more accurately saves money and increases crop yield.

The common thread here is knowledge of what is actually going on, right there in the ground. The term for this is “ground truth”. The usual way to obtain ground truth is by putting your feet on the dirt and using your eyes. But this doesn’t scale well, since crops can cover very large areas. Eyeballing things from a vehicle doesn’t help much, because if there are areas of poor growth mixed throughout a field, it’s very hard to perceive that visually. One part of a field looks pretty much like any other when you’re at anything near eye level. You don’t have the right perspective. That is where drones come in.

What Drones Do

The kinds of drones that have a use in agriculture might look like toys but they are much more obedient. They have capabilities that include:

  • Carrying cameras and taking pictures tirelessly, consistently, and with precision.
  • Having an unobstructed bird’s-eye view of things, thanks to being airborne.
  • Being fast; they are able to cover large areas quickly without needing roads or paths.

Those abilities are used, along with some back-end software processing, to quickly get a depth of information on crops that simply wasn’t accessible before.

Here is what happens: a human gives a drone a flight plan that covers a field. The drone flies over the field in a pattern while taking pictures with one or more special cameras. These pictures are geotagged and overlap each other. After landing, software is used to stitch the photos together into a large mosaic, and processing is done to interpret the amount of light reflected in different wavelengths. Generally speaking, the healthier the plants, the more they reflect in near-infrared – a higher wavelength than visible light not normally perceptible to humans, but can be captured by cameras. Processing this data makes areas of healthy growth stand out compared to everything else, and makes areas of poor growth or stressed plants easy to identify. Having this data generated nearly on demand opens the door to all kinds of better decision-making for growers. Problems are detected earlier and more accurately, and no time is wasted checking on areas where all is well.

How Plant Health Gets Measured

Plant leaves – technically their main pigment, chlorophyll – strongly absorb visible light for use in photosynthesis. But healthy plant leaves also strongly reflect near-infrared (NIR). Different species of plants reflect somewhat differently, but non-plant material does not reflect in this way at all. Gathering this data and processing it in a way that makes it useful is how remote imaging detects plant health.

Leaf reflectivity in different wavelengths [source: Agribotix, used with permission]In the 70’s a method called Normalized Difference Vegetation Index (NDVI) was developed. It was a method of using the NIR reflection phenomenon to quickly and simply identify vegetated areas and their overall condition from satellite imagery that received infrared and near-infrared wavelengths. The principle is well understood and can be observed and experimented with by modifying modern digital cameras to allow them to pick up the correct wavelengths. A number of projects on Hackaday.io explore NDVI, and we covered a “seeing plant health in infrared” project that now provides an open-source tool for NDVI processing and experimentation.

NDVI isn’t quite enough by itself, however. It has practical limitations, and the issues satellite imaging has had to solve are different from the challenges drone imagery faces. Applying the concept to drone imagery has had its own quirks, as this blog entry by startup Agribotix explains in some detail. But fundamentally the NDVI principle is still what allows modern drones to take pictures of a crop with specialized cameras, use computers to process that data, and turn it into a color-coded aerial map that is easily understood.

NDVI processed images. Left: crop growth as a green gradient blended with normal visual images [source: Agribotix, used with permission] Right: NDVI processing showing plant growth as a red gradient [source: Public Lab Wiki, CC-SA 3.0] What’s Around the Next Corner

Providing growth maps and health reports in a timely fashion is currently the most mature application of drones in agriculture, but it is not the only one. Other applications are on the map – such as using drones to not only plan fertilizer application, but to dispense fertilizer directly. In areas where irrigation farming is common, managing a large amount of irrigation hardware is a big job that could be helped by airborne observation. Anything that puts more complete information into grower’s hands faster is a potential for growth, and drones allow more ways to do that than ever before.

Of Course, There are Things in the Way

Implementation issues for emerging industries aside, there are still plenty of other challenges to drone usage. Drone usage outdoors is highly weather dependent. Flying can be limited by weather, but changing conditions like varying sunlight and cloud cover can make data harder to process. Most crops are in rural areas with limited internet access and cellular infrastructure. Limited flight time is a factor, especially for multirotor aircraft. Drones and their cameras are expensive. They might be capable of autonomous flight, but they still require maintenance and skilled operators. Drones are not very good at carrying payloads – we will probably see package delivery by drone before fertilizer application by drone is common. And of course, there’s uncertain government regulation.

There are plenty of variables in agriculture and drone usage only applies to a small number of them, but it’s a budding industry that seems to be growing as quickly as it can – and the world of agriculture is certainly no stranger to high-tech solutions and expensive equipment. But the devil is always in the details, and even when you have all the pieces available, implementation can be rocky. Have any of you been involved this growing industry? Let us know in the comments – we want to hear from you!

Filed under: drone hacks, Featured, green hacks, Interest, Original Art, slider

An Affordable Ultrasonic Soldering Iron

จันทร์, 05/09/2016 - 18:01

One of the most interesting facets of our community of hackers and makers comes from its never-ending capacity to experiment and to deliver new technologies and techniques. Ample demonstration of this came this morning, in the form of [Hunter Scott]’s Hackaday.io project to create an ultrasonic soldering iron. This is a soldering technique in which the iron is subjected to ultrasonic vibrations which cavitate the surface of the materials to be soldered and remove any oxides which would impede the adhesion of the solder. In this way normally unsolderable materials such as stainless steel, aluminium, ceramic, or glass can be soldered without the need for flux or other specialist chemicals. Ultrasonic soldering has been an expensive business, and [Hunter]’s project aims to change that.

This iron takes the element and tip from a conventional mains-powered soldering iron and mounts it on the transducer from an ultrasonic cleaner. The transducer must be given an appropriate load which in the case of the cleaner is furnished by a water bath, or it will overheat and burn out. [Hunter]’s load is just a soldering iron element, so to prevent transducer meltdown he keeps the element powered continuously but the transducer on a momentary-action switch to ensure it only runs for the short time he’s soldering. The project is not quite finished so he’s yet to prove whether this approach will save his transducer, but we feel it’s an interesting enough idea to make it definitely worth following.

This is the first ultrasonic soldering project we’ve featured here at Hackaday. We have however had an ultrasonic plastic welder before, and an ultrasonic vapour polisher for 3D prints. It would be good to think this project could spark a raft of others that improve and refine DIY ultrasonic soldering designs.

Filed under: tool hacks

X-Ray Everything!

จันทร์, 05/09/2016 - 15:01

We’re not 100% sure why this is being done, but we’re 110% happy that it is. Someone (under the name of [The X-Ray Playground]) is putting interesting devices under an X-ray camera and posting videos of them up on YouTube. And he or she seems to be adding a few new videos per day.

Want to see the inner workings of a pneumatic microswitch? Or is a running pair of servo motors more your speed? Now you know where to look. After watching the servo video, we couldn’t help but wish that a bunch of the previous videos were also taken while the devices were being activated. The ball bearing wouldn’t gain much from that treatment, but the miniature piston certainly would. [X-Ray Playground], if you’re out there, more working demos, please!

How long the pace of new videos can last is anyone’s guess, but we’re content to enjoy the ride. And it’s just cool to see stuff in X-ray. If we had a postal address, we know we’d ship some stuff over to be put under the lens.

We don’t have as many X-ray hacks as you’d expect, which is probably OK given the radioactivity and all. But we have seen [MikesElectricStuff] taking apart a baggage-scanner X-ray machine in exquisite detail, and a DIY fluoroscope (yikes!), so we’re not strangers. Who needs Superman? We all have X-ray vision these days.

Thanks [OiD] for the tip!

Filed under: misc hacks, slider

Hackaday Prize Entry: Raimi’s Bionic Arm

จันทร์, 05/09/2016 - 12:00

Sometimes, the most amazing teams make the most wonderful things happen, and yet, there is just not enough time to finish all the features before the product ships. This is what happened to Raimi, who came to this world missing a right hand and half of her right forearm. Raimi is now 9 years old, and commercial mechatronic prostheses are still only available to those who can afford them. When Raimi’s father approached [Patrick Joyce] to ask him for help in building an affordable prosthesis, he knew it would matter, and went right to work.

[Patrick] started by researching for existing designs and found some good ideas, custom builds and well documented open source projects out there. However, individual requirements shorten the list of what is applicable: Raimi also needs an extension for her partial forearm, and the design must be lightweight and compact enough for a kid. Because Raimi is growing rapidly, the design must be prepared to grow with her.

Eventually, [Patrick] decided to create his own design, incorporating some of the best ideas he found in the documentations of Enabling The Future and Open Bionics. He started with the design of a single finger, using servo-actuated tendons and return springs to actuate the finger within the space constraints of a children’s hand. A 3D-printed prototype confirmed the concept, and [Patrick] went on by designing a full hand and forearm. Squeezing the whole mechanical system into the tiny arm required the whole hand to be operated from only three servos. While the four fingers were tied to a single servo through a whiffletree system, the thumb additionally received a rotational joint, allowing for different grip styles. An Arduino controls the servos and displays the current grip-mode of the thumb on an OLED display. Later, myoelectric sensors shall be employed to give Raimi a natural interface to control her bionic arm.

You may be impressed by [Patrick Joyce’s]  design and build of a functional, miniaturized, mechatronic hand, but you will be certainly blown away to hear that he does all this using an eye-gaze system and a joystick. After 8 years of suffering from progressive MND/ALS, [Patrick] is quadriplegic with a small amount of movement left in his right arm and fingers. Still, even though he lost the ability to move his limbs, he has not lost the ability to move something in this world. Taking our own motoric abilities for granted, we may not realize how much our ability to manipulate the world around us forms our mind as well. A functional prosthesis can make a big difference to a young girl whose mind is still developing, deciding whether to accept the world as it is – or to change it for the better. Enjoy the video!

“Raimi’s Arm – Bionic Arm for Kids” is one of the winners of $1,000 in the first round of the HackadayPrize2016.

The HackadayPrize2016 is Sponsored by:


Filed under: Medical hacks, The Hackaday Prize

3D Printer Prints Sound

จันทร์, 05/09/2016 - 09:01

People like music, but they are also visual creatures. Perhaps that’s why music visualization is such a common project. Usually, you think of music visualization as using LEDs or a computer screen. However, [Gieeel] did his music visualization using a 3D printer.

Sure, the visualization is a little static compared to LEDs, but it does make an interesting conversation piece. The actual process isn’t very difficult, once you have the idea. [Gieeel] captured the waveform in Audacity, did a screen capture, and then converts the image to an SVG file using Inkscape.

From there, you can use many different CAD tools to convert the image into a 3D object. [Gieeel] used Autodesk Fusion 360 and had the resulting object professionally 3D printed.

We’ve seen other kinds of sound sculptures before. Of course, we’ve also seen a lot of traditional visualizations, as well.

Filed under: 3d Printer hacks, musical hacks

Hackaday Links: It’s Mother’s Day And You Forgot

จันทร์, 05/09/2016 - 06:00

[AvE] noticed someone was having trouble with their Nepeploid Shilden Inversker, and after a sinusoidal lambda deplanarization test, noticed the dinglebop wouldn’t pass through the grumbo. [AvE] is probably just some guy who wears overalls to bed, but he does know a polyfractal magnetorestrictor when he sees one. To wit, he has a novel application of Eularian magnetronics resulting in a friction factor over unityGame changing stuff here, from the guy who brought you the beer stein made out of an oil filter.

It was soft launched at the Midwest RepRap Festival this year, and now Lulzbot’s TAZ 6 is finally out. The biggest new feature? The electronics ‘brain box’ holds everything, including the power supply. This tower of brain box makes the Taz 6 harder to build from source, but there are unconfirmed reports that Lulzbot may sell this brainbox separately.

Boldport, and founder [Saar Drimer] are the cream of the crop when it comes to artistic PCBs. Boldport’s catalog and [Saar]’s portfolio include a tribute to [Bob Pease], a beautiful board with multicolor solder masks, and an emergency business card. Now Boldport is doing a beautiful PCB of the month club. It’s called Boldport Club, and each three-month membership gets you three months of pretty PCBs. The shop will also stop taking orders for the Boldport club 25 hours after this post goes live. If you missed the boat on the club, you can still get in on the pretty PCB action – we have the Boldport cordwood puzzle available in the Hackaday store.

The Apple IIgs was the last gasp of the Apple II before that platform was phased out for the Macintosh. Despite being mostly forgotten, except for thousands of units in middle school computer labs until the 2000s, it was a very interesting machine, with a wavetable synth, real multitasking, a GUI, and very high resolution graphics. After 30-odd years the IIgs now has quadraphonic sound. The 4soniq card was introduced at the WOzFest III conference last month, and it will give an Apple IIgs with four channels of audio output.

There’s a lot of stuff happening next weekend, and Hackaday is going to be there. If you’re at the Maker Faire Bay Area, Hackaday is taking over a pub. It’s on Saturday night, so it doesn’t conflict with the bring-a-hack at an undisclosed location on Sunday night. Me? I’m going to hamvention, mostly for the purposes of documenting the two parking lots full of swap meet. Find me and I’ll get you some Hackaday swag.

Filed under: Hackaday Columns, Hackaday links

Rasberry Pi Zero Plays Every Simpsons Episode Ever at Random

จันทร์, 05/09/2016 - 03:01

If there’s a better use for Raspberry Pi Zero than a shuffler for episodes of “The Simpsons”, we haven’t heard about it.

Creator [Stephen Coyle] took inspiration from [Will Smith]’s mention of the burning need for such a device on the Tested podcast years back. The gadget is just a Zero with a familiar yellow button – hopefully it’s Pantone 116 C – that randomly selects an episode from the SD card. [Stephen] is clear on his opinion of over half of the program’s oeuvre, having found only seasons 2 through 10 worthy to load on the card. As an aside, we feel pretty old after seeing that all 593 episodes can easily fit on a 128GB SD card – we started out religiously recording every episode on VHS tapes, but had to stop after a few seasons when the collection got too big to handle.

If ripping episodes from DVDs isn’t your style, or you’re still into the first-run stuff, you might want to check out this confusingly named Smart Homer so you never miss an episode.

[via /r/raspberry_pi]

Filed under: home entertainment hacks, Raspberry Pi

DIY Cast AR-15 Receivers Are More Interesting Than Expected

จันทร์, 05/09/2016 - 00:01

For some reason the US News media decided on the AR-15 as the poster child of guns that should not be allowed to be made for, or sold to, the consumer. The words still out on the regulation, but, in a very American response, a whole market sprang up around people saying, “Well, then we’ll just make our own AR-15.”

Ordinarily, we wouldn’t cover this sort of thing, but the work [AR-15Mold] is doing is just so dang interesting. They sell a product that enables the home user to cast an AR-15 receiver out of high performance resin. In the process they made a really informative three part video on the casting process.

A lot of people are interested in the product, and having fun with it. In this two part video series, [Liberty Marksman] cast their receivers and test them to destruction. In one video they see how many rounds they can fire out of the gun before it breaks. When it breaks, they excitedly tear down the gun to see where it failed.

It’s quite a bit of fun to watch. Videos after the break.


Filed under: chemistry hacks, weapons hacks

Running a Hackerspace is Hard: Egypt Edition

อาทิตย์, 05/08/2016 - 22:31

It’s no secret that it’s difficult to run a hackerspace. Different personalities, different material requirements, and often constrained spaces can require continual negotiation. But if you think that having the metalworking types getting their shavings on your electronics bench is a problem, try having your entire hackerspace demolished on short notice.

The situation in Cairo is far from normal at the moment. The building that Cairo Hackerspace had recently moved to was raided, closed for two months, and then re-opened under strict surveillance in February.

All was well until a part of the building unexpectedly collapsed. Then they got a demolition order, followed by postponement, followed by armed police entering anyway and breaking stuff, followed by a further declaration of the building as safe, and now a heritage site. And all of this over a week’s time. While some of the art studios in the Townhouse were saved, the Cairo Hackerspace’s space is gone.

The good news? Nobody got hurt in all of this, and the Cairo Hackerspace crew were able to get their gear out after the initial demolition notice. They’ve been working on a mobile hackerspace-in-a-van approach lately, so hopefully they’ll be able to keep on hacking.

So when you’re bickering over who didn’t clean up the hackspace’s coffee machine, or the proper location of your favorite soldering iron, think kindly about the Cairo crew and get back to doing what you do best — projects.

How about you? What hackerspace tales do you have? Contact us through the tips line — we’d love to hear.

Filed under: Hackaday Columns, Hackerspaces, news

Smallest MIDI Synth, Again!

อาทิตย์, 05/08/2016 - 21:01

Not content with fitting a tiny square-wave MIDI synthesizer into a MIDI plug, [Mitxela] went on to cram a similar noisemaker into a USB plug itself.

Besides being physically small, the code is small too, as well as the budget. It uses V-USB for the USB library running on an ATtiny85, and a couple of passive parts. His firmware (apparently) takes in MIDI notes and spits out square waves.

Nothing too amazing, until you think about the miniaturization effort. To get this thing to fit inside the metal case of a USB plug, [Mitxela] cut out some of the plastic, and crammed the parts inside. And by “crammed” we mean ground everything down that wouldn’t fit. The through-hole Zener diodes were just a little bit too tall, so they went under the grinder. The end of the ATtiny stuck out just a tad. More grinding.

Once everything fit, it went back into the metal case with a bit of insulating tape, and it was done. Due to the form-factor alone, it was a lot smaller than his previous effort, and certainly even less useful! We see further room for miniaturization through trimming down the piezo buzzer case. We also see no point in that either.

This project seems to have started out as a finger-study for building USB MIDI controllers, so we’re looking forward to cool things coming down the pike. Until then, enjoy the so-far smallest monophonic USB MIDI squarewave synth that we’ve seen.

Filed under: Microcontrollers, musical hacks

Gyroman Walks with Just One Motor

อาทิตย์, 05/08/2016 - 18:01

For some reason, we seem to really want our robots to walk on two legs like we do. And this despite how much the robots themselves want to be made out of motors, which match up so naturally with wheels. The result is a proliferation of inventive walking mechanisms. Here’s another.

Gyroman is a 3D printed gyroscope with legs. The gyroscope is geared down to lift one leg and then the other. First-semester physics, that we still find a little bit magical, makes the gyro precess and the robot turns a bit. Time these just right and it walks. See the video below for a demo. (Admittedly, Gyroman looks like he’s had a bit too much to drink as he winds down.)

This mechanism is the brainchild of John W. Jameson, who patented it. Who knew that there were even toys based on a motorized version of the mechanism? (We envision recreating this with spinning hard-drive platters.)

So using gyros to walk is old, but we’re dredging it up because it’s so cool and we’ve never covered it. Moreover, the same basic idea of using a gyroscope for motive force keeps popping up over and over again. Which leads us to wonder, what other gyro-based robots are lurking around out there?

Filed under: robots hacks, toy hacks

Tiling your TV Remote

อาทิตย์, 05/08/2016 - 15:01

The Tile is a small Bluetooth chip, speaker, and enough battery for a year in a keychain format. If you lose your keys in the morning, simply use the app on your phone to find the keychain. If you lose your phone simply get out your second phone.

This planned obsolescence didn’t jive with [JM] when his Tile stopped being discoverable. He didn’t want to toss a gadget that had served him so well into the landfill. So, like any good hacker, he cracked its plastic case open.

The Tile itself is a really interesting product. The largest component is the battery which has tabs spot-welded to its surface. Attached to those is a well laid out board. [JM] points out the clever use of spring contacts to engage the piezo element for the speaker as a nice example of good design for manufacture.

The hack itself was pretty easy to complete. Some electrical tape and soldering was all it took to embed the tile into the remote. Now he can take out his phone and press a button to hear a forlorn beep coming from under the couch cushions.

Filed under: home hacks, slider

Hackaday Prize Entry: A Cheaper Soldering Solution

อาทิตย์, 05/08/2016 - 12:00

Everyone goes through a few phases during their exploration of electrons, and nowhere is this more apparent than the choice of soldering iron. The My First Soldering Iron™ is an iron that plugs directly into the wall, and doesn’t have temperature control. They’re cheap, and electronics isn’t for everyone, giving the quitters the opportunity to take up woodburning as a hobby. The next step up is a temperature controlled iron, probably an Aoyue or Hakko. The best soldering iron? You’re looking at a Metcal or Weller, and your wallet will become a few hundred dollars lighter.

Your My First Soldering Iron™ need not be terrible, though. For his project for The Hackaday Prize, [HP] is working on a soldering iron that is cheap, accurate, and uses the very nice Weller RT tips. No, it’s not as good as a Metcal or proper Weller, but it’s good enough for some fine soldering work and will give the Aoyues and Hakkos a run for their money.

If price is a reasonable measure of the quality of a soldering iron, the irons that use these Weller RT tips are the best irons around. The tips, though, are pretty cheap: about $30, which gets you a heater and thermistor and not much else. There have been numerous reverse engineering efforts for this iron ([1] and [2]), and even a few Arduino-based circuits that replicate the functionality of the Weller base unit.

[HP] is going in a different direction to heat these iron tips. Instead of building a big box to hold the electronics, he’s building everything into the handle of the soldering iron. With brains donated from an ATMega168, a few op-amps, MOSFETS, and a single power jack, [HP] can heat up this soldering iron tip in a compact, hand-held unit.

For his Hackaday Prize entry, [HP] did a rundown of soldering pen in a video. You can check that out below.

The HackadayPrize2016 is Sponsored by:

Filed under: The Hackaday Prize, tool hacks

Raspberry Pi Balloon Goes Too High, Goes Boom, But Survives

อาทิตย์, 05/08/2016 - 09:01

Some people like to get high on a Wednesday afternoon. [Kevin Hubbard] of Black Mesa Labs likes to get really high. Even higher than intended: last month, he flew a helium balloon powered by a Raspberry Pi to 103,000 feet. It was only supposed to go to 90,000, but a fault in the code for the controller meant that it went higher, burst and plunged to the ground. All thanks to an extra hash mark in his code.

[Kevin] was part of a team called the Balloongineers who are competing in the Global Space Balloon Challenge, a project to simultaneously fly balloons from multiple locations. The Balloongineers entry was called HAB1, built around a Raspberry Pi, an FPGA watchdog system, a uBlox GPS and an Iridium satellite modem. The idea was that their balloon would zoom up to 90,000 feet, where it would release some helium gas, hover, and move eastwards with the prevailing winds. reporting back via satellite as it went. Unfortunately, something went wrong. The balloon didn’t report back properly, and kept on rising, eventually reaching over 100,000 feet, where it burst and fell to earth.

[Kevin] thought all was lost, including the expensive satellite modem that HAB1 used. But the next day, his balloon sent him an email, reporting that it was hale and hearty at an altitude of 300 feet. After recovery, he analyzed HAB1, and figured out what had happened: a single mistyped hash mark had caused the system to lock up when it tried to open the vent to release the gas.

What saved the rig was the foresight [Kevin] had in building it. Although the system didn’t work fully as planned, the FPGA watchdog (nicknamed the Lizard Brain) eventually noticed that the main computer was locked up, and rebooted it, enabling the system to report back to [Kevin]. An additional recovery mode woke the system once an hour sent a location and went back to sleep, which allowed the small battery to keep powering the system until it could get a signal out the morning after. That’s a smart piece of design in a system that allowed them to recover the hardware, even though the main objective of hovering at 90,000 feet wasn’t achieved.

[Kevin] ends his writeup of the flight with a few notes that any engineer would be wise to consider. Primary among these is his decision to have the system check very rarely for manual overrides over the satellite connection. He decided to do this to save money: checking for messages on Iridium costs a certain amount each time you do it. If he had checked more frequently, he might have been able to fix the problem earlier by venting the helium manually, leading to a more controlled descent and recovery. In any project, a failure can only be useful if you can figure out what the problem was, gathering as much information as possible to help you avoid it next time.

Filed under: Raspberry Pi

Thinking of You: IoT Style

อาทิตย์, 05/08/2016 - 06:01

Do you have loved ones who live far away? Or do you just want an interesting starter ESP8266 project to get your feet wet? If the answer to either of these questions is “yes”, we’ve got just the project for you. [Craig Lindley] built a “thinking of you” button-and-LED display device that helps people keep in touch, in a very simple way.

We like the minimalism of the design. One party presses their button, electrons flow, WiFis WiFi, data travels through a set of tubes, and an LED far away glows a pre-arranged color. The other side can signal back to say “hi” as well. It’s a cute item to have on your desk, or wherever you spend the most time. If you’re new to all of this, you can hardly beat the circuit for its simplicity.

Yeah, you could totally just send the other person a text message or an e-mail. But then you don’t get an excuse to play around with NodeMCU, and it just lacks the personal hacker touch. The code is available in a zip file here, and if you want to stay in touch with someone other than [Craig]’s sisters, you’ll probably want to customize it a bit.

Filed under: wireless hacks

Single Photon Source for Quantum Computing and Experimentation

อาทิตย์, 05/08/2016 - 03:00

One challenge to building optical computing devices and some quantum computers is finding a source of single photons. There are a lot of different techniques, but many of them aren’t very practical, requiring lots of space and cryogenic cooling. Recently, researchers at the Hebrew University of Jerusalem developed a scalable photon source on a semiconductor die.

Using nanocrystals of semiconductor material, the new technique emits single photons, and in a predictable direction. The nanocrystals combine with circular nanoantennas made of metal and dielectric produced with conventional fabrication technology. The nanoantennas are concentric circles resembling a bullseye and is used to ensure that the photons travel the correct direction with little or no angular deviation.

A single IC could contain many photon sources and they operate at room temperature. We’ve talked about quantum tricks with photons before. Quantum mechanics is another popular topic.

Filed under: news

Hacklet 106 – Robots That Teach

อาทิตย์, 05/08/2016 - 00:01

One of the best ways to teach electronics and programming is with hands-on learning. Get the concepts off the computer screen and out into the real world. Students of all ages have been learning with robots for decades. Many older Hackaday readers will remember the turtle robots. These little ‘bots would drive around drawing shapes created in the logo programming language. This week’s Hacklet is all about the next generation of robots that teach electronics, mechanics, programming, and of course, hacking. So let’s check out some of the best educational robot projects on Hackaday.io!

We start with [Tom Van den Bon] and Edubot Controller (Benny). Buying one or two robots can get expensive. Equipping a classroom full of them can break the bank. [Tom] is hoping to make robots cheaper and more accessible with Edubot, his entry in the 2016 Hackaday prize. Edubot rides on a 3D printed frame with low-cost gear motors for a drive system. Edubot’s brain is an STM32F042, a low-cost ARM processor from ST micro. The micro and motor drives are integrated into a custom board [Tom] designed. He’s has even begun creating lesson plans so students of various ages and skill levels can participate and learn.

Next up is [Joshua Elsdon] with Micro Robots for Education. Big robots can be intimidating. They can also cause some damage when hardware and software created by budding engineers doesn’t operate as expected. Tiny robots though, are much easier to wrangle. [Joshua ] may have taken tiny to an extreme with these robots. Each robot is under 2 cm square. The goal is for each one to cost less than  £10 to produce. These micro bots have big brains with their ATmega328P micro controllers. [Joshua] is currently trying to figure out a low-cost way to produce wheels for these robots.

Next we have [shamylmansoor] with 3D printed mobile robot for STEM education. Robots are expensive, and international shipping can make them even more expensive. [Shamyl] is shooting for a robot which can be made locally in Pakistan. 3D printing is the answer. The robot’s chassis can be printed on any FDM printer. Wheels,and tires are low-cost units. Motors are RC servos modified for continuous rotation. The brains of the robot is an Arduino Mega 2560, which should provide plenty of inputs for sensors. [Shamyl] even included a solderless breadboard so students can prototype circuits and sensors right on the robot’s body.


Finally we have [Rodolfo] with Plobot. Plobot is a robot designed for the youngest hackers – those from four to seven years old. [Rodolfo] designed Plobot to be programmed with RFID cards. Each card contains a command such as move forward, turn, start, and reset. Many of the language mechanics are inspired by the Scratch programming language. Plobot’s processor is a Sanguino, running [Rodolfo’s] custom code. An ESP8266 allows Plobot to be connected to the outside world via WiFi. [Rodolfo] has even created a custom over the air update system for Plobot’s firmware. Plobot has already been tested with students, where it made a great showing. We’re hoping both [Rodolfo] and Plobot do well in the 2016 Hackaday Prize!

If you want more mind hacking goodness, check out our brand new educational robot list! Did I miss your project? 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!

Filed under: Hackaday Columns, robots hacks