Better, Smaller WiFi Throwies

October 26, 2015 by Brian Benchoff 47 Comments

Because the world doesn’t have enough electronic junk floating around, [Victor] has improved the WiFi Throwie.

A decade ago, when strong, cheap magnets, bright LEDs, and small coin cell batteries were materials fresh to hacking, someone had a great idea: tape all these items up and throw them on bridges and overpasses. The LED throwie was born, and while we’re sure the biggest installation of LED throwies looked cool, it’s really just a small-scale environmental disaster.

Since then, the ESP8266 was created, and the world now has a tiny WiFi-enabled computer that’s the size of a postage stamp. Yes, WiFi throwies already exist, but coin cells don’t work with the ESP. This means the compact and tiny ESPs are laden down with heavy lithium cells. [Victor] had a better solution: tiny lithium batteries for quadcopters exist, so why not use those?

[Victor] ended up using a small 100mAh 3.7V Lipo battery from a tiny quadcopter for this build. 100mAh isn’t a lot, but in sleep mode, the ESP only uses about 15mAh, or about 6 hours of run time. Sending a picture takes 30 seconds at 120ma, or about 120mAh, so even with a tiny battery no bigger than the ESP itself, this diminutive web server can handle 100 connections before the battery dies.

While not recommended unless you intend to retrieve your throwable web server, it is an interesting example of the latest and cheapest technology that made a throwable webserver possible; 10 years ago, both the ESP and a battery this small would have been unthinkable.

This Is Not Your Father’s FORTRAN

October 26, 2015 by Rud Merriam 109 Comments

I learned to program FORTRAN IV in the spring of 1968 while working as an engineering technician in water resources. One of the engineers knew of my interest in computers and asked if I would like to learn FORTRAN. He needed to calculate the biological oxygen demand in streams but didn’t have any interest in programming. I jumped at the chance.

This was the days of big iron when the term computer meant a room full of heavily air-conditioned equipment. The State University of New York at Buffalo had an IBM 704 but they soon upgraded to a CDC 6400. To help pay for it they were inviting people to attend a seminar on FORTRAN so they could use the system. My job was with a small State of NY office and getting approval for me to attend was surprisingly easy.

Off I went for 6 weeks of training on one night a week. I still have my black “A Guide to Fortran IV Programming” by [Daniel McCracken]. For years, this was the FORTRAN bible, commonly referred to as just “McCracken”.

The programming went well and somewhere out there is a very old paper with a reference to the results it generated about the Chadakoin River flowing through Jamestown, NY.

This is FORTRAN’s strength – scientific calculations. It’s name says it: FORmula TRANslation.

Origins and FORTRAN IV

[John W. Backus] suggested to IBM a language to replace assembly language. Development began in 1953 for the IBM 704 and the project reached fruition in 1957. Not only was it the first general purpose high-level language, just beating out COBOL and LISP, but its compiler optimized the code since it needed to compete head-on with assembly language. It was the C compiler of its day in that regard.

That was not the only reason it attained success. Reducing the number of punched cards needed for a program by a factor of 20 over assembly helped considerably.

In those days, you needed to use a key punch to create a deck of punch cards. To be really good you had to know how to create a programming card that would let you skip through the fields on a FORTRAN card, or how to edit a card by duplicating it and holding one of the cards in place while you typed in new characters. Because of my fascination with computers I’d taken a key punching and automation machines class in high school so I was all set.

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Don’t Look Now, Nothing Will Happen –Zeno Of Elea

October 26, 2015 by Brandon Dunson 53 Comments

The Greek philosopher [Zeno of Elea] proposed that an arrow in flight was in fact not in motion and its visible movement is only an illusion. A simple example of this is to glance at an arrow in flight, doing this causes our mind to store a snapshot of a motionless arrow. [Zeno] further defended this argument by stating that if an object has to travel a finite distance to reach a destination then the finite distance can be divided in half and the object must first reach this halfway point before arriving at the destination. This process can be repeated an infinite number of times, creating an infinite number of points that the object must occupy before reaching the destination thus it can never arrive at the destination.

Whoa, that’s a bit heavy. Let’s take a second here to think about this and never arrive at the conclusion, shall we?

So what does a fancy mathematics parlor trick have to do with the fact that we have all seen an arrow arrive at its destination? Recent experiments conducted at Cornell University have in fact verified the Zeno Effect. Researchers were able to achieve this by having atoms suspended between lasers in temperatures ~1 nano degree above absolute zero so that the atoms arrange themselves in a lattice formation. As per usual in quantum mechanics when observed, the atoms had an equal possibility of being anywhere within the space of the lattice. However, when they were observed at high enough frequencies the atoms remain motionless, bringing the quantum evolution to a halt.

Killed By A Machine: The Therac-25

October 26, 2015 by Adam Fabio 158 Comments

The Therac-25 was not a device anyone was happy to see. It was a radiation therapy machine. In layman’s terms it was a “cancer zapper”; a linear accelerator with a human as its target. Using X-rays or a beam of electrons, radiation therapy machines kill cancerous tissue, even deep inside the body. These room-sized medical devices would always cause some collateral damage to healthy tissue around the tumors. As with chemotherapy, the hope is that the net effect heals the patient more than it harms them. For six unfortunate patients in 1986 and 1987, the Therac-25 did the unthinkable: it exposed them to massive overdoses of radiation, killing four and leaving two others with lifelong injuries. During the investigation, it was determined that the root cause of the problem was twofold. Firstly, the software controlling the machine contained bugs which proved to be fatal. Secondly, the design of the machine relied on the controlling computer alone for safety. There were no hardware interlocks or supervisory circuits to ensure that software bugs couldn’t result in catastrophic failures.

The case of the Therac-25 has become one of the most well-known killer software bugs in history. Several universities use the case as a cautionary tale of what can go wrong, and how investigations can be lead astray. Much of this is due to the work of [Nancy Leveson], a software safety expert who exhaustively researched the incidents and resulting lawsuits. Much of the information published about the Therac (including this article) is based upon her research and 1993 paper with [Clark Turner] entitled “An Investigation of the Therac-25 Accidents”. [Nancy] has since published updated information in a second paper which is also included in her book.

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A More Correct Horse Battery Staple

October 26, 2015 by Brian Benchoff 97 Comments

Passwords are terrible. The usual requirements of a number, capital letter, or punctuation mark force users to create unmemorable passwords, leading to post-it notes; the techniques that were supposed to make passwords more secure actually make us less secure, and yes, there is an xkcd for it.

[Randall Munroe] did offer us a solution: a Correct Horse Battery Staple. By memorizing a long phrase, a greater number of bits are more easily encoded in a user’s memory, making a password much harder to crack. ‘Correct Horse Battery Staple’ only provides a 44-bit password, though, and researchers at the University of Southern California have a better solution: prose and poetry. Just imagine what a man from Nantucket will do to a battery staple.

In their paper, the researchers set out to create random, memorable 60-bit passwords in an English word sequence. First, they created an xkcd password generator with a 2048-word dictionary to create passwords such as ‘photo bros nan plain’ and ’embarrass debating gaskell jennie’. This produced the results you would expect from a webcomic. The best ‘alternative’ result was found when creating poetry: passwords like “Sophisticated potentates / misrepresenting Emirates” and “The supervisor notified / the transportation nationwide” produced a 60-bit password that was at least as memorable as the xkcd method.

Image credit xkcd

Developed On Hackaday – It’s A Badge. No, It’s The HaDge

October 26, 2015 by Anool Mahidharia 14 Comments

Sometime back, we announced start of a new project under the “Developed on Hackaday” series – a Badge for the Hackaday community. At its core, this badge is a single node in an Internet of Badges. At every event this badge is deployed at, a Hackaday Sub-Etha mesh network will be created, and each badge will be able to transmit and receive messages from other badge wearers. There are plans for an Sub-Etha to Internet gateway, so even if badge wearers are on the other side of the world, they’re still connected through the HaDge network.

Things have been moving along quickly, so I thought of doing a quick round-up and share progress with the community. First off, it has a name. HaDge, as in HackaDay Badge. Our objectives up until now were to set up a team, name the project, set up repositories and lock down on a working bill of materials. Within a few weeks, we’ve got all of that tied down. The HaDge group chat channel has been super active, and everyone’s been pitching in with ideas and suggestions. A spreadsheet seemed like a good idea – it let everyone add in their suggestions regarding candidate parts, create a feature list and then talk about it on the channel.

We realized early on that building the hardware is going to take some time. So in the interim, we need a dev kit platform to get in to the hands of the software developers so they can start working on the smarts that will power the HaDge. [Michele Perla] had already built JACK (Just another Cortex kit) – a development kit powered by the Atmel SAM D21. It’s pretty bare bone with just the bare minimum of parts to make it work while keeping an eye on reliability. The microcontroller+radio on the HaDge is the Atmel SAM R21 – a close relative of the D21, so it made sense to respin the JACK and create HACK (Hackaday Cortex kit) – a development kit powered by the Atmel SAM R21 that is going to be used as the core of the HaDge. [Michele] has worked hard single-handedly to complete the design and it is now ready to go for PCB fabrication soon. We are just awaiting some feedback and review of the Antenna part of the design. None of us on the hardware team have a strong RF-fu so we don’t want to make an avoidable mistake. If you’d like to review and help vet the HACK design, grab the design files from the github repo and let us know.

Once HACK board layout is cleared for fabrication, we’ll work on building kits that can be sent out to the software folks. We will also be working on porting the HACK design in to KiCad and this is something I have already stared work on. I started by using the neat Eagle2KiCad conversion tool by [LachlanA]. It’s not perfect, but it does reduce the work involved in porting over from Eagle to Kicad. Once that is done, hardware development for the actual HaDge will see some progress – keep a watch on the project page.

Better Capacitors Through Nanotechnology

October 25, 2015 by Al Williams 29 Comments

Traditionally, capacitors are like really bad rechargeable batteries. Supercapacitors changed that, making it practical to use a fast-charging capacitor in place of rechargeable batteries. However, supercapacitors work in a different way than conventional (dielectric) capacitors. They use either an electrostatic scheme to achieve very close separation of charge (as little as 0.3 nanometers) or electrochemical pseudocapacitance (or sometime a combination of those methods).

In a conventional capacitor the two electrodes are as close together as practical and as large as practical because the capacitance goes up with surface area and down with distance between the plates. Unfortunately, for high-performance energy storage, capacitors (of the conventional kind) have a problem: you can get high capacitance or high breakdown voltage, but not both. That’s intuitive since getting the plates closer makes for higher capacitance but also makes the dielectric more likely to break down as the electric field inside the capacitor becomes higher with both voltage and closer plate spacing (the electric field, E, is equal to the voltage divided by the plate spacing).

[Guowen Meng] and others from several Chinese and US universities recently published a paper in the journal Science Advances that offers a way around this problem. By using a 3D carbon nanotube electrode, they can improve a dielectric capacitor to perform nearly as well as a supercapacitor (they are claiming 2Wh/kg energy density in their device).

The capacitor forms in a nanoporous membrane of anodic aluminum oxide. The pores do not go all the way through, but stop short, forming a barrier layer at the bottom of each pore. Some of the pores go through the material in one direction, and the rest go through in the other direction. The researchers deposited nanotubes in the pores and these tubes form the plates of the capacitor (see picture, right). The result is a capacitor with a high-capacity (due to the large surface area) but with an enhanced breakdown voltage thanks to the uniform pore walls.

To improve performance, the pores in the aluminum oxide are formed so that one large pore pointing in one direction is surrounded by six smaller pores going in the other direction (see picture to left). In this configuration, the capacitance in a 1 micron thick membrane could be as high as 9.8 microfarads per square centimeter.

For comparison, most high-value conventional capacitors are electrolytic and use two different plates: a plate of metallic foil and a semi-liquid electrolyte. You can even make one of these at home, if you are so inclined (see video below).

We’ve talked about supercapacitors before (even homebrew ones), and this technology could make high capacitance devices even better. We’ve also talked about graphene supercaps you can build yourself with a DVD burner.

It is amazing to think how a new technology like carbon nanotubes can make something as old and simple as a capacitor better. You have to wonder what other improvements will come as we understand these new materials even better.

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