4 Port USB, Raspberry Pi Zero Piggy-Back Hack

December 3, 2015 by 54 Comments

[Frederick] decided his new Zero needed a USB hub. He noticed a small, on hand, USB hub was the same size as the Zero. As any good hacker would, he stripped it from its case to piggy-back it onto the Zero. What’s with the piggy-backing since we just saw that with another Zero hack that added a WiFi dongle? Is it something in the water? Nah, probably just a natural fit with the mini-sized Zero.

Foam and elastic bands make a next arrangement
Tricky wiring to the hub’s USB

It certainly helps that the USB and power pads on the back of the Zero are available and of a good size to accept direct, soldered wire connections. The USB connections on the hub were a little more tricky. The wires were soldered to the surface mount pins of the mini-B connector. But [Frederick] managed to get that done, also.

A nice advantage of this hack is that a couple of soldered jumper wires let the Zero draw power from the hub’s wall-wart, eliminating one cable from those needed to work with the Pi. Using hot glue for strain relief on the wiring is a nice touch. To keep the boards from shorting he put a piece of foam between them and help them together with elastic bands. Simple and easy.

Kay Igwe Explains Brain Gaming Through SSVEP

December 3, 2015 by 12 Comments

We had some incredible speakers at the Hackaday SuperConference. One of the final talks was given by [Kay Igwe], a graduate electrical engineering student at Columbia University. [Kay] has worked in nanotechnology as well as semiconductor manufacturing for Intel. These days, she’s spending her time playing games – but not with her hands.

Many of us love gaming, and probably spend way too much time on our computers, consoles, or phones playing games. But what about people who don’t have the use of their hands, such as ALS patients? Bringing gaming to the disabled is what prompted  [Kay] to work on Control iT, a brain interface for controlling games. Brain-computer interfaces invoke images of Electroencephalography (EEG) machines. Usually that means tons of electrodes, gel in your hair, and data which is buried in the noise.

[Kay Igwe] is exploring a very interesting phenomenon that uses flashing lights to elicit very specific, and easy to detect brain waves. This type of interface is very promising and is the topic of the talk she gave at this year’s Hackaday SuperConference. Check out the video of her presentation, then join us after the break as we dive into the details of her work.

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Retrocomputing On A Chip

December 3, 2015 by 10 Comments

New electrical components enable us to reconstruct old wiring more efficiently. Especially, the accessible and cheap FPGA kits which offer the possibility to put together wiring of many old computers as an “on-a-chip” solution.

When I managed to get a hold of an old bubble LED display and a pretty mechanical matrix keyboard, I decided to build a replica of an old single board computer. Logical options seemed to be to build either KIM-1 or Heathkit ET-3400. Replicas of KIM-1 already exist, even for Arduino, so my task would be reduced to connect the keyboard and display. But then I told myself that I would use the fact that my bubble display has 9 positions as an excuse to build the legendary Czechoslovak Single Board Computer PMI-80 which used the same display. My replica is an FPGA, or rather an FPGA emulator of this very computer.

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An Introduction To Series Elastic Actuators For A Robot

December 3, 2015 by 13 Comments

Perhaps one of the most interesting YouTube channels to follow right now is [James Bruton’s] channel for XRobots.co.uk — he’s a prop maker, a toy maker — and as his site implies, a robotics guru. Put them altogether and watch him make some of your childhood dream projects come true. He’s currently working on a real-life robot creation of Ultron, and he’s messing around with Series Elastic Actuators right now.

In an earlier part of the project, he built a small robotic arm to demonstrate the motion capture suit he’s going to use to control Ultron (if all goes according to plan he’ll have a walking robot following his every move!). He showed how the basic RC servo motor driven arm works, and how it probably wouldn’t be the best to scale up since it has no external feedback — if he has a full size Ultron robot swinging its arms around, someone could get hurt.

Which led him to designing his own prototype Series Elastic Actuators using an Arduino, potentiometers, some elastics, and a geared DC motor.

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Nuts About Volts

December 3, 2015 by 30 Comments

Among multimeters one instrument stands far and above the rest. An object desired for its accuracy, resolution and shear engineering beauty. I speak of course of the HP 3458A. That’s right, not Keysight, not even Agilent (though of course it goes by those brands too). The 3458A was released in 1989, when HP was still… well… HP. An elegant meter from a more civilized age. As the HP Journal documents, the 3458A was a significant engineering feat and has remained in production (and largely unchallenged) for the last 26 years.

keyBut what, you might ask, makes the 3458A such a significant and desirable instrument? It’s all in the digits. The 3458A is one of the few 8.5 digit multimeters available. It is therefore sensitive to microvolt deflections on 10 volt measurements. It is this ability to distinguished tiny changes on large signals that sets high precision multimeters apart. Imagine weighing an elephant and being able to count the number of flies that land on its back by the change in weight. The 3458A accomplishes a similar feat.

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How Store Anti-Theft Alarms Work: Magnetostriction

December 3, 2015 by 44 Comments

Now that’s uncanny. Two days before [Ben Krasnow] of the Applied Science YouTube blog posted this video on anti-theft tags that use magnetostriction, we wrote a blog post about a firm that’s using inverse-magnetostriction to generate electricity. Strange synchronicity!

[Ben] takes apart those rectangular plastic security tags that end up embarrassing everyone when the sales people forget to demagnetize them before you leave the store. Inside are two metal strips. One strip gets magnetized and demagnetized, and the other is magnetostrictive — meaning it changes length ever so slightly in the presence of a magnetic field.

A sender coil hits the magnetostrictive strip with a pulsed signal at the strip’s resonant frequency, around 58kHz. The strip expands and contracts along with the sender’s magnetic field. When the sender’s pulse stops, the strip keeps vibrating for a tiny bit of time, emitting an AC magnetic field that’s picked up by the detector. You’re busted.

The final wrinkle is the magnetizable metal strip inside the tag. When it’s not magnetized at all, or magnetized too strongly, the magnetostrictive strip doesn’t respond as much to the sender’s field. When the bias magnet is magnetized just right, the other strip rings like it’s supposed to. Which is why they “demagnetize” the strips at checkout.

We haven’t even spoiled [Ben]’s explanation. He does an amazing job of investigating all of this. He even measures these small strips changing their length by ten parts per million. It’s a great bit of low-tech measurement that ends up being right on the money and deserves the top spot in your “to watch” list.

And now that magenetostriction is in our collective unconscious, what’s the next place we’ll see it pop up?

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Radio Receiver Build Log And More

December 3, 2015 by 8 Comments

At Hackaday, we like to see build logs, and over on Hackaday.io, you can find plenty of them. Sometimes, though, a builder really outdoes themselves with a lot of great detail on a project, and [N6QW’s] Simple-Ceiver project certainly falls into that category. The project logs document many different stages of completeness, and we linked the first one for you as a starting point, but you’ll definitely want to read up to the present. (There were 16 parts, some spanning multiple posts, last time we checked).

It is definitely worth the effort though. The project started out as a direct conversion receiver, but the design goes through and converts it into a superheterodyne receiver. Along the way, [N6QW] shares construction techniques, design advice, and even simulation plots (backed up with actual scope measurements). The local oscillator, of course, uses an Arduino and an AD9850 synthesizer.

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