ETextile Spring Break Tackles Signal Blocking, Audio Generation, And Radio Transmissions

April 20, 2018 by Lara Grant 12 Comments

Finding a killer application for e-textiles is the realm of the hacker and within that realm, anything goes. Whether it’s protecting your digital privacy with signal shielding, generating audio with a wearable BeagleBone or 555 timer, or making your favorite garment into an antenna, the eTextile Spring Break is testing out ways to combine electronics and fabric.

You may be asking yourself “What are e-textiles good for?”. Well, that’s an excellent question and likely the most common one facing the industry today. I’m afraid I won’t be able to give a definitive answer. As an e-textile practitioner, I too am constantly posing this question to myself. There’s an inherently personal nature to fabric worn on the body and to our electronic devices that makes this answer elusive. Instead of trying to fabricate some narrow definition, what I offer is a look at topics of interest, material experimentation, and technical exploration through the lens of a week-long event held recently in New York called eTextile Spring Break.

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Life On Contract: Lowering Your Cost Without Dropping Your Price

April 20, 2018 by Donald Papp 17 Comments

Last time in Life on Contract, I discussed ways to figure out a starting point on how much to charge for your services. However, sometimes you and a client may wish to work together but for some reason they cannot (or do not wish to) pay what you have decided to charge. If you are inexperienced, it can be tempting to assume you have overpriced yourself and discount down to what they are willing to pay. But if your price is a number you have chosen for reasons you can explain, dropping it is not something you should do unless you have thought about it carefully.

Instead of just agreeing to do the same work but for less money, it is often possible to offer a lower overall cost without cheapening the value of your work. I’ll share a process I use to find opportunities to make this happen.

It Should be Win-Win, Not Hard Sell

The best case scenario is a client wants your service, your cost is within their budget, and everyone agrees to work together. Tragically, the process isn’t always that smooth. If cost is an issue, the alternative to lowering your price is to fine-tune what you provide to better fit the actual needs. To do that, you will need two things:

A detailed understanding of your own time and costs for the work.
Knowledge of what things your client considers most important.

By intimately knowing your own costs, you can figure out where to make savings without scrimping on the things your client considers important.
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When 4 + 1 Equals 8: An Advanced Take On Pointers In C

April 19, 2018 by Sven Gregori 104 Comments

In our first part on pointers, we covered the basics and common pitfalls of pointers in C. If we had to break it down into one sentence, the main principle of pointers is that they are simply data types storing a memory address, and as long as we make sure that we have enough memory allocated at that address, everything is going to be fine.

In this second part, we are going to continue with some more advanced pointer topics, including pointer arithmetic, pointers with another pointer as underlying data type, and the relationship between arrays and pointers. But first, there is one particular pointer we haven’t talked about yet.

The one proverbial exception to the rule that pointers are just memory addresses is the most (in)famous pointer of all: the NULL pointer. Commonly defined as preprocessor macro (void *) 0, we can assign NULL like any other pointer.

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Fix Your Insecure Amazon Fire TV Stick

April 18, 2018 by Tom Nardi 48 Comments

I recently spent a largely sleepless night at a hotel, and out of equal parts curiosity and boredom, decided to kill some time scanning the guest network to see what my fellow travelers might be up to. As you’d probably expect, I saw a veritable sea of Samsung and Apple devices. But buried among the seemingly endless number of smartphones charging next to their sleeping owners, I found something rather interesting. I was as picking up a number of Amazon-made devices, all of which had port 5555 open.

As a habitual Android tinkerer, this struck me as very odd. Port 5555 is used for Android Debug Bridge (ADB), a development tool used to control and perform various administrative tasks on an Android device over the network or (more commonly) locally over USB. The number of users who would have legitimately needed to enable network ADB on their devices is surely rather low, so to see a half dozen of them on the network at the same time seemed improbable to say the least.

Why would so many devices manufactured by Amazon all have network ADB enabled? I realized there must be a connection, and it didn’t take long to figure it out.

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Beatrice Tinsley And The Evolution Of Galaxies

April 17, 2018 by Kristina Panos 10 Comments

It seems almost absurd now, but cosmologists once assumed that galaxies of a given type were all the same and didn’t change. Because of this assumption, galaxies were used as a redshift or light-based yardstick to measure distances in the universe. But what if some galaxies were intrinsically redder than others? Little to no thought was given to their origins, compositions, or evolution until Beatrice Tinsley came along.

Beatrice saw galaxies as changing bodies of stars. She believed that they grew, evolved, and died because they’re made of stars, and that’s what their star populations did. To lump all galaxies together and use them as a standard candle was an oversimplification. Beatrice created the first computer model of a galaxy to prove her point and in doing so, she founded the field of galaxy evolution.

If you’ve never heard of Beatrice, don’t feel bad. Just as her career was really beginning to take off, she developed cancer and died shortly after her 40th birthday. Though her life was short, her influence on cosmology is long-reaching. Continue reading “Beatrice Tinsley And The Evolution Of Galaxies” →

Beeping The Enemy Into Submission

April 17, 2018 by Christian Trapp 45 Comments

In July 1940 the German airforce began bombing Britain. This was met with polite disagreement on the British side — and with high technology, ingenuity, and improvisation. The defeat of the Germans is associated with anti-aircraft guns and fighter planes, but a significant amount of potential damage had been averted by the use of radio.

Night bombing was a relatively new idea at that time and everybody agreed that it was hard. Navigating a plane in the dark while travelling at two hundred miles per hour and possibly being shot at just wasn’t effective with traditional means. So the Germans invented non-traditional means. This was the start of a technological competition where each side worked to implement new and novel radio technology to guide bombing runs, and to disrupt those guidance systems.

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Two-Cent Temperature Sensors

April 16, 2018 by Elliot Williams 89 Comments

When they need to add temperature control to a project, many hackers reach for a K-type thermocouple for their high-temperature needs, or an integrated temperature-sensing IC when it doesn’t get that hot. The thermocouple relies on very small currents and extremely high gain, and you pretty much need a dedicated IC to read it, which can be expensive. The ICs aren’t as expensive, but they’re basically limited to boiling water. What do you do if you want to control a reflow oven?

There’s a cheaper way that spans a range between Antarctic winter and molten solder, and you’ve probably already got the parts on your shelf. Even if you don’t, it’s only going to run you an extra two cents, assuming that you’ve already got a microcontroller with an ADC in your project. The BOM: a plain-vanilla diode and a resistor.

I’ve been using diodes as temperature sensors in three projects over the last year: one is a coffee roaster that brings the beans up to 220 °C in hot air, another is a reflow hotplate that tops out around 210 °C, and the third is a toner-transfer iron that holds a very stable 130 °C. In all of these cases, I don’t really care about the actual numerical value of the temperature — all that matters is reproducibility — so I never bothered to calibrate anything. I thought I’d do it right for Hackaday, and try to push the humble diode to its limits for science.

What resulted was a PCB fire, test circuits desoldering themselves above 190 °C, temperature probes coming loose, and finally a broken ramekin and 200 °C peanut oil all over my desk. Fun times! On the other hand, I managed to get out enough data to calibrate some diodes, and the results are fantastic. The circuits under test included both best practices and the easiest thing that could possibly work, and the results are pretty close. This is definitely a technique that you want to have under your belt for most temperature ranges. The devil is in the details, of course, so read on!

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