3D Printering: Print Smoothing Tests With UV Resin

March 8, 2018 by Donald Papp 16 Comments

Smoothing the layer lines out of filament-based 3D prints is a common desire, and there are various methods for doing it. Besides good old sanding, another method is to apply a liquid coating of some kind that fills in irregularities and creates a smooth surface. There’s even a product specifically for this purpose: XTC-3D by Smooth-on. However, I happened to have access to the syrup-thick UV resin from an SLA printer and it occurred to me to see whether I could smooth a 3D print by brushing the resin on, then curing it. I didn’t see any reason it shouldn’t work, and it might even bring its own advantages. Filament printers and resin-based printers don’t normally have anything to do with one another, but since I had access to both I decided to cross the streams a little.

The UV-curable resin I tested is Clear Standard resin from a Formlabs printer. Other UV resins should work similarly from what I understand, but I haven’t tested them.

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The Pontoon Bridge Being Floated As An NYC Transit Fix

March 8, 2018 by Alex Weinberg 96 Comments

New York City’s L train carries about 400,000 passengers a day, linking Manhattan and Brooklyn and bringing passengers along 14th Street, under the East River, and through the neighborhoods of Williamsburg, Bushwick, Ridgewood, Brownsville, and Canarsie. About 225,000 of these passengers pass through the Canarsie Tunnel, a two-tube cast iron rail tunnel built below the East River between Manhattan and Brooklyn in 1924. Like many other New York City road and subway tunnels, the Canarsie Tunnel was badly damaged when Hurricane Sandy’s storm surge inundated the tubes with million of gallons of salt water. Six years later, the impending closure of the tunnel is motivating New Yorkers to develop their own ambitious infrastructure ideas.

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Evolution Of The Worlds Oldest Computer Festival

March 7, 2018 by Tom Nardi 32 Comments

The Trenton Computer Festival (TCF) doesn’t have the name recognition of big technology conferences like DEF CON or HOPE. It’s not even as well known as smaller more localized conferences like DerbyCon, ShmooCon, or the Hackaday Superconference. In fact, there’s a good chance that most readers have never even heard of TCF. But despite not holding a place in the hacker lexicon, TCF has plenty to boast about. Its played host to technology luminaries from Bill Gates to Richard Stallman, and now in its 43rd year, holds the title as the longest continually running technology festival in the world.

Bill Gates giving the keynote at TCF in 1989

When originally conceived in 1976, the show was devoted to the dawning age of the personal computer, but since then has evolved into a celebration of technology as a whole. When TCF kicks off on March 17th, there won’t be a media blitz or huge corporate sponsorship. There won’t be a simultaneous online stream of the event, and the only badges worn by speakers or attendees will be of the paper variety.

What you will find at TCF is a full schedule of talks given by people who are passionate about technology in its varied forms. These run the gamut from quantum computing to lock picking, from Arduino to Space Shuttle avionics.

At the heart of TCF is co-founder and current Chair Dr Allen Katz. I recently had the opportunity to speak with Dr Katz about the challenges of running a conference of this type, and the secret to keeping relevant in a wildly changing technology landscape.

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Friday Hack Chat: Everything About The ESP

March 7, 2018 by Brian Benchoff 16 Comments

When the ESP-8266 first arrived, it was a marvel. For two dollars, you could buy a simple module that could serve as a bridge between WiFi networks and microcontroller projects. It understood the Hayes command set, it didn’t use much power, and, as noted before, it only cost two dollars. The idea of cheap and accessible Internet of Things things was right there for the taking.

Then hackers figured out what was actually going on inside the ESP-8266. It was a full-blown microcontroller. There was Lua stuff you could put on it. You could program it with the Arduino IDE. It had WiFi. This was the greatest microcontroller release in the last decade, and it came from a company no one had ever heard of.

Since then, the ESP ecosystem has bloomed, and there’s a new ESP on the block. The ESP-32 is an even more powerful WiFi and Bluetooth-enabled chip that’s just as easy to program, and it costs three dollars. Microcontrollers have never been cooler.

For this week’s Hack Chat, we’re going to be talking all about the ESP. Our guest for this Hack Chat should need no introduction, but if you’re unfamiliar, [Sprite_tm] plays video games on his keyboard and has installed Linux on a hard drive. He also works at Espressif, the company behind the ESP-8266 and ESP-32, where he’s applied his skills towards tiny Game Boys and miniature Macs.

During this week’s Hack Chat, we’re going to be covering everything about the ESP, including peripherals, ultra-low power consumption, SIP packages, and what’s coming up for the ESP family. You are, as always, welcome to submit your questions for [Sprite]; just add those as a comment on the Hack Chat page.

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. [Sprite]’s in China, so we’re not doing this one at the usual time: This week, the Hack Chat will happen at 7:00 am, Pacific, Friday, March 9th. Want to know what time this is happening in your neck of the woods? Have a countdown timer!

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

A Bit More Than A Microphone: The Electret Story

March 7, 2018 by Jenny List 35 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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Hot Air Surgery Revives A Cheap Windows Tablet

March 6, 2018 by Tom Nardi 39 Comments

[Jason Gin] recently wrote in to tell us about his adventures replacing the eMMC storage chip on a cheap Windows tablet, and we have to say, it’s an impressive amount of work for a device which apparently only cost him $15. Surely much better pieces of hardware have been tossed in the trash for less serious failures than what ailed his DigiLand DL801W tablet. We’d love to see the lengths this guy would go to restore something a bit higher up the food chain.

As any good hacker knows, you can’t fix the problem until you understand it. So the first step [Jason] took was to conduct some troubleshooting. The tablet would only boot to the EFI shell, which didn’t do him much good since there was no on-screen keyboard to interact with it. But he had the idea of trying to connect a USB keyboard via an OTG adapter, and sure enough that got him in. Once he was able to enter commands into the EFI shell, he attempted to read from a few different sectors of the eMMC drive, only to get the same nonsense repeating data. So far, not looking good.

But before he fully committed to replacing the eMMC drive, he wanted a second opinion. Using the same USB OTG adapter, he was able to boot the tablet into a Windows 10 environment, and from there got access to some drive diagnostic tools. The software reported that not only was the drive reporting to be half the appropriate size, but that writing to the chip was impossible.

With the fate of the tablet’s Foresee NCEMBS99-16G eMMC chip now confirmed, [Jason] decided it was time to operate. After pulling the tablet apart and masking off the PCB with Kapton tape to protect it from the heat, he slowly went in with his hot air rework station to remove the failed chip. But rather than put another low-end chip in its place, he used this opportunity to replace it with a Samsung KLMBG4GEND-B031. Not only does this chip have twice the capacity of the original, it should be noticeably faster.

With the new Samsung eMMC chip installed, [Jason] put the tablet back together and was able to successfully install Windows 10 onto it. Another piece of tech saved from the big landfill in the sky.

If the casual confidence of this particular repair wasn’t enough of a clue, this isn’t the first time he’s showed some unruly eMMC chips who’s boss.

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.

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