Desperately Trying To Find A Use For The ChugPlug

March 7, 2018 by Tom Nardi 21 Comments

[AkBKukU] writes in to tell us of his experiments with the rather vile-sounding “ChugPlug”, an odd portable AC power bank designed for the express purpose of powering MacBook chargers. It would seem more efficient to simply build a DC power bank with a MagSafe connector to cut out the charger all together, but presumably there is some market for this particular niche device. Especially at the $15 they are currently selling for on Amazon.

Unfortunately, the ChugPlug that [AkBKukU] bought doesn’t seem to work. After some experimenting he found that it appears to only be outputting 80 VAC, obviously too low for many devices to function. But he reasoned that some things, like switch mode power supplies or restive loads, might still work. He just needed to come up with a way to plug them into the ChugPlug.

If his testing setup gives you a case of sweaty palms, you aren’t alone. He breaks open a dead MacBook charger to recover the female AC connector, and then solders that directly to an AC grounding adapter. The resulting pigtail lets [AkBKukU] plug in various AC loads while allowing him to probe the wires with his multimeter and oscilloscope.

Once he’s satisfied his hack works conceptually, that is, he’s able to plug arbitrary AC loads into this purpose-built battery pack, he follows up with a less dangerous looking adapter. Making use of the shell of the dead MacBook charger and what some might describe as a salacious amount of hot glue, he produces a compact and relatively safe looking device that will let him use his handicapped ChugPlug as a general purpose source of AC power.

It’s not the most elaborate portable power supply we’ve ever seen, and certainly wouldn’t be our first choice in an emergency, but at least [AkBKukU] managed to wring some use out of the thing in the end.

Continue reading “Desperately Trying To Find A Use For The ChugPlug” →

A Bit More Than A Microphone: The Electret Story

March 7, 2018 by Jenny List 34 Comments

When designing a microphone assembly the other day, I reached for an electret condenser microphone capsule without thinking. To be strictly accurate I ordered a pack of them, these small cylindrical microphones are of extremely high quality for their relatively tiny price.

It was only upon submitting the order that I had a thought for the first time in my life: Just what IS an electret condenser microphone?

A condenser microphone is easy enough to explain. It’s a capacitor formed from a very thin conductive sheet that functions as the diaphragm, mounted in front of another conductor, usually a piece of mesh. Sound waves cause the diaphragm to vibrate, and these vibrations change the capacitance between diaphragm and mesh.

If that capacitance is incorporated into an RC circuit with a very high impedance and a high voltage is applied, a near constant charge is placed upon it. Since the charge stays constant, changing the capacitance causes a tiny voltage fluctuation that can be retrieved as the audio signal from the microphone. Condenser microphones built in this way can be extremely high quality, but come at the expense of needing a high voltage power supply to supply the charge and an amplifier to buffer and magnify the audio.

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What’s Inside A Neonode Laser Sensor?

March 6, 2018 by Elliot Williams 16 Comments

Every once in a while, you get your hands on a cool piece of hardware, and of course, it’s your first instinct to open it up and see how it works, right? Maybe see if it can be coaxed into doing just a little bit more than it says on the box? And so it was last Wednesday, when I was at the Embedded World trade fair, and stumbled on a cool touch display floating apparently in mid-air.

The display itself was a sort of focused Pepper’s Ghost illusion, reflected off of an expensive mirror made by Aska3D. I don’t know much more — I didn’t get to bring home one of the fancy glass plates — but it looked pretty good. But this display was interactive: you could touch the floating 2D projection as if it were actually there, and the software would respond. What was doing the touch response in mid-air? I’m a sucker for sensors, so I started asking questions and left with a small box of prototype Neonode zForce AIR sensor sticks to take apart.

The zForce sensors are essentially an array of IR lasers and photodiodes with some lenses that limit their field of view. The IR light hits your finger and bounces back to the photodiodes on the bar. Because the photodiodes have a limited angle over which they respond, they can be used to triangulate the distance of the finger above the display. Scanning quickly among the IR lasers and noting which photodiodes receive a reflection can locate a few fingertips in a 2D space, which explained the interactive part of the floating display. With one of these sensors, you can add a 2D touch surface to anything. It’s like an invisible laser harp that can also sense distance.

The intended purpose is fingertip detection, and that’s what the firmware is good at, but it must also be the case that it could detect the shape of arbitrary (concave) objects within its range, and that was going to be my hack. I got 90% of the way there in one night, thanks to affordable tools and free software that every hardware hacker should have in their toolbox. So read on for the unfortunate destruction of nice hardware, a tour through some useful command-line hardware-hacking tools, and gratuitous creation of animations from sniffed SPI-like data pulled off of some test points.

Continue reading “What’s Inside A Neonode Laser Sensor?” →

Love Open Source But Hate People? Get OpenKobold

March 5, 2018 by Tom Nardi 47 Comments

[Tadas Ustinavičius] writes in to tell us of his latest project, which combines his two great loves of open source and annoying people: OpenKobold. Named after the German mythical spirit that haunts people’s homes, this tiny device is fully open source (hardware and software) and ready to torment your friends and family for up to a year on a CR1220 battery.

The design of the OpenKobold is quite simple, and the open source nature of the project makes this an excellent case study for turning an idea into a fully functional physical object.

Beyond the battery and the buzzer module, the OpenKobold utilizes a PIC12F675, a transistor, and a few passive components. This spartan design allows for a PCB that measures only 25 x 20 mm, making it very easy to hide but fiendishly difficult to try to track down later on.

But the real magic is in the software. The firmware that [Tadas] has written for the PIC not only randomizes how often the buzzer goes off, but how long it will sound for. This makes predicting the OpenKobold with any sort of accuracy very difficult, confounding the poor soul who’s searching their home or office for this maddening little device.

Hackers have a long and storied history of creating elaborate pranks, putting the OpenKobold in very good company. From randomly replaying signals from a remote control to building robotic cardboard burglars, we’ve seen our fair share of elaborate pranks from the community.

One Man’s Quest For A Desktop Spherical Display

March 5, 2018 by Tom Nardi 20 Comments

[Nirav Patel] is a man on a mission. Since 2011 he has been obsessed with owning a spherical display, the kind of thing you see in museums and science centers, but on a desktop scale. Unfortunately for him, there hasn’t been much commercial interest in this sort of thing as of yet. Up to this point, he’s been forced to hack up his own versions of his dream display.

That is until he heard about the Gakken Worldeye from Japan. This device promised to be exactly what he’s been looking for all these years, and he quickly snapped up two of them: one to use, and one to tear apart. We like this guy’s style. But as is often the case with cheap overseas imports, the device didn’t quite live up to his expectations. Undaunted by the out of the box performance of the Worldeye, [Nirav] has started documenting his attempts to improve on the product.

These displays work by projecting an image on the inside of a frosted glass or plastic sphere, and [Nirav] notes that the projection sphere on the Worldeye is actually pretty decent. The problem is the electronics, namely the anemic VGA resolution projector that’s further cropped down to a 480 pixel circle by the optics. Combined with the low-quality downsampling that squashes down the HDMI input, the final image on the Worldeye is underwhelming to say the least.

[Nirav] decided to rip the original projector out of the Worldeye and replace it with a Sony MP-CL1 model capable of a much more respectable 1280×720. He came up with a 3D printed bracket to hold the MP-CL1 in place, and has put the files up on Thingiverse for anyone who might want to play along at home. The results are better, but unfortunately still not great. [Nirav] thinks the sphere is physically too small to support the higher resolution of the MP-CL1, plus the optics aren’t exactly of the highest quality to begin with. But he’s just glad he didn’t have to build this one from scratch.

Going back to our first coverage of his DIY spherical display in 2012, we have to say his earliest attempts are still very impressive. It looks like this is a case of the commercial market struggling to keep up with the work of independent hackers.

Badgelife: From 1 To 100

March 5, 2018 by Brian Benchoff 11 Comments

Blame it on the falling costs of printed circuit boards, the increased accessibility of hardware design tools, the fact that GCC works on microcontrollers now, whatever the ‘maker movement’ is, or any one of a number of other factors. There’s a hardware demoscene now. Instead of poking bits, writing code, and dividing by zero to create impressive multimedia demonstrations on a computer, there is a small contingent of very creative people who are building their own physical hardware, just for the hell of it. They’re pushing boundaries of what can be done with hardware design, demonstrating manufacturing know-how, and turning a (small) profit while doing it. This is badgelife, the tiny subculture dedicated to creating custom electronic conference badges.

At Hackaday, we’ve been doing a deep dive into the rigors of this demoscene of hardware, and last week we had the pleasure of hosting a meetup with some of the big players of the badgelife community as guests of honor. There were, of course, talks discussing the trials and tribulations of designing, manufacturing, and shipping hundreds of pieces of hardware on a limited budget with not enough time. If you want to know how hard electronic design and manufacturing can be, you want to check out these talks below. Continue reading “Badgelife: From 1 To 100” →

Graphing Calculator Dual Boots With Pi Zero

March 4, 2018 by Tom Nardi 41 Comments

The nearly limitless array of consumer gadgets hackers have shoved the Raspberry Pi into should really come as no surprise. The Pi is cheap, well documented, and in the case of the Pi Zero, incredibly compact. It’s like the thing is begging to get grafted into toys, game systems, or anything else that could use a penguin-flavored infusion.

But this particular project takes it to the next level. Rather than just cramming the Pi and a cheap LCD into his Numworks graphing calculator, [Zardam] integrated it into the device so well that you’d swear it was a feature from the factory. By exploiting the fact that the calculator has some convenient solder pads connected to its SPI bus, he was able to create an application which switches the display between the Pi and the calculator at will. With just a press of a button, he’s able to switch between using the stock calculator software and having full access to the internal Pi Zero.

In a very detailed write-up on his site, [Zardam] explains the process of getting the Pi Zero to output video over SPI. The first part of the battle was re-configuring the GPIO pins and DMA controller. After that, there was the small issue of writing a Linux SPI framebuffer driver. Luckily he was able to find some work done previously by [Sprite_TM] which helped him get on the right track. His final driver is able to push 320×240 video at 50 FPS via GPIO, more than enough to kick back with some DOOM.

With video sorted out, he still needed a way to interface the calculator’s keyboard with the Pi. For this, he added a function in his calculator application that echoed the keys pressed to the calculator’s UART port. This is connected to the Pi, where a daemon is listening for key presses. The daemon then generates the appropriate keycodes for the kernel via uinput. [Zardam] acknowledges this part of the system could do with some refinement, but judging by the video after the break, it works well enough for a first version.

We’ve seen the Pi Zero get transplanted into everything from a 56K modem to the venerated Game Boy, and figured nothing would surprise us at this point. But we’ve got to say, this is one of the cleanest and most practical builds we’ve seen yet.

[Thanks to EdS for the tip]

Continue reading “Graphing Calculator Dual Boots With Pi Zero” →