This Chromecast Volume Knob Has A Certain ’70s Chic

January 31, 2019 by 10 Comments

Chromecast devices have become popular in homes around the world in the last few years. They make it easy to cast audio or video from a smartphone or laptop, to a set of speakers or a display connected to the same network. [Akos] wanted to control the volume on these devices with a single, simple piece of equipment, rather than always reaching for a smartphone. Thus was built the CastVolumeKnob.

The project began by using Wireshark to capture data sent by the pychromecast library. Once [Akos] understood the messaging format, this was implemented in MicroPython on an ESP8266. A rotary encoder is used as a volume knob, and a Neopixel ring is used for visual feedback as to the device being controlled and the current volume level.

Further work was done to improve usability, with an ATtiny85 microcontroller being used to monitor the encoder for button presses before waking up the ESP8266, greatly reducing power consumption. The device is also rechargeable, thanks to an 18650 lithium polymer battery, and charger and boost converter boards. It’s all wrapped up in a sleek 3D printed case, with a translucent bezel for the LEDs and a swanky machined aluminium knob as the cherry on top.

It’s a homemade device that nonetheless would be stylish and unobtrusive in the living room environment. We imagine it proves very useful when important phone calls come in and it’s necessary to cut the stereo down to a more appropriate volume.

For another take, check out this USB volume knob with a nice weighty feel, courtesy of lead shot.

K40 Gets A Leg Up With Open Source Z Table

January 31, 2019 by 14 Comments

If you’ve done even the most cursory research into buying a laser cutter, you’ve certainly heard of the K40. Usually selling for around $400 USD online, the K40 is not so much a single machine as a class of very similar 40 watt CO2 lasers from various Chinese manufacturers. As you might expect, it takes considerable corner cutting to drive the cost down that low, but the K40 is still arguably the most cost-effective way to get a “real” laser cutter into your shop. If you’re willing to do some modifications on the thing, even better.

One of the shortcomings of the K40 is that it lacks a Z axis, and with thick material that needs multiple cuts at increasingly deeper depths, this can be a hassle. [Aaron Peterson] decided to take it upon himself to design and build an adjustable Z table for the K40 at his local makerspace (River City Labs), and being the swell guy that he is, has made it available under an open source license so the rest of the K40-owning world can benefit from his work.

[Aaron] started the design with a number of goals which really helped elevate the project from a one-off hack to a sustainable community project. For one, he only wanted to use easily available commodity hardware to keep the cost down. The most complex components should all be 3D printable so the design would be easy to replicate by others, and finally, he wanted the user to have the ability to scale it in all dimensions. The end result is a electronically controlled lifting platform that anyone can build, for any laser cutter. It doesn’t even have to be limited to laser cutters; if you have a need for precisely raising or lowering something, this design might be exactly what you’re looking for.

The table is primarily constructed out of 15×15 aluminum extrusion, and uses standard hardware store expanded wire mesh as a top surface. Height is adjusted by rotating the four 95 mm T8 leadscrews with a GT2 belt and pulleys, which prevents any corner from getting out of sync with the others. Connected to a standard NEMA 17 stepper motor, this arrangement should easily be capable of sub-millimeter accuracy. It looks as though [Aaron] has left controlling the stepper motor as an exercise for the reader, but an Arduino with a CNC shield would likely be the easiest route.

We’ve seen a lot of hacking around the K40 over the last couple of years, from spring loaded beds to complete rebuilds which are hardly recognizable. If you’re looking for a cheap laser with a huge catalog of possible hacks and modifications, you could do a lot worse than starting with this inexpensive Chinese machine.

Down The Rabbit Hole Of Electronics Manufacturing

January 31, 2019 by 6 Comments

If you want to build hundreds of a thing (and let’s face it, you do) now is a magical time to do it. Scale manufacturing has never been more accessible to the hardware hacker, but that doesn’t mean it’s turn-key with no question marks along the way. The path is there, but it’s not well marked and is only now becoming well-traveled. The great news is that yes, you can get hundreds of a thing manufactured, and Kerry Scharfglass proves that it’s a viable process for the lone-wolf electronics designer. He’s shared tips and tricks of the manufacturing process in a prefect level of detail during his talk at the 2018 Hackaday Superconference.

Kerry is the person behind the Dragonfly badge that was sold at DEF CON over the last two years. Yes, this is #badgelife, but it’s also a mechanism for him to test the waters for launching his own medium-run electronics business. And let’s face it, badge making can be a business. Kerry treats it as such in his talk.

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Linux Fu: Easier File Watching

January 31, 2019 by 22 Comments

In an earlier installment of Linux Fu, I mentioned how you can use inotifywait to efficiently watch for file system changes. The comments had a lot of alternative ways to do the same job, which is great. But there was one very easy-to-use tool that didn’t show up, so I wanted to talk about it. That tool is entr. It isn’t as versatile, but it is easy to use and covers a lot of common use cases where you want some action to occur when a file changes.

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3D Print That Charging Dock For Your 3DS

January 31, 2019 by 15 Comments

The Switch is the new hotness and everyone wants Nintendo’s new portable gaming rig nestled in a dock next to their TV, but what about Nintendo’s other portable gaming system? Yes, the New Nintendo 3DS can get a charging dock, and you can 3D print it with swappable plates that make it look like something straight out of the Nintendo store.

[Hobby Hoarder] created this charging dock for the New Nintendo 3DS as a 3D printing project, with the goal of having everything printable without supports, and able to be constructed without any special tools. Printing a box is easy enough, but the real trick is how to charge the 3DS without any special tools. For this, [Hobby Hoarder] turned to the small charging contacts on the side of the console. All you do is apply power and ground to these contacts, and the 3DS charges.

Normally, adding contacts requires pogo pins or hilariously expensive connectors, but [Hobby Hoarder] has an interesting solution: just add some metal contacts constructed from LED leads or paper clips, and mount it on a spring-loaded slider. A regular ‘ol USB cable is scavenged, the wires stripped, and the red and black lines are attached to the spring-loaded slider.

There is a slight issue with the charging voltage in this setup; the 3DS charges at 4.6 Volts, and USB provides 5 Volts. If you want to keep everything within exacting specs, you could add an LDO linear regulator, but there might be issues with heat dissipation. You could use a buck converter, but at 0.4 Volts, you’re probably better off going with the ‘aaay yolo’ theory of engineering.

[Hobby Hoarder] produced a few great videos detailing this build, and one awesome video detailing how to print multicolored faceplates for this charging dock. It’s an excellent project, and a great example of what can be done with 3D printing and simple tools.

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AI On Raspberry Pi With The Intel Neural Compute Stick

January 31, 2019 by 58 Comments

I’ve always been fascinated by AI and machine learning. Google TensorFlow offers tutorials and has been on my ‘to-learn’ list since it was first released, although I always seem to neglect it in favor of the shiniest new embedded platform.

Last July, I took note when Intel released the Neural Compute Stick. It looked like an oversized USB stick, and acted as an accelerator for local AI applications, especially machine vision. I thought it was a pretty neat idea: it allowed me to test out AI applications on embedded systems at a power cost of about 1W. It requires pre-trained models, but there are enough of them available now to do some interesting things.

You can add a few of them in a hub for parallel tasks. Image credit Intel Corporation.

I wasn’t convinced I would get great performance out of it, and forgot about it until last November when they released an improved version. Unambiguously named the ‘Neural Compute Stick 2’ (NCS2), it was reasonably priced and promised a 6-8x performance increase over the last model, so I decided to give it a try to see how well it worked.

 

I took a few days off work around Christmas to set up Intel’s OpenVino Toolkit on my laptop. The installation script provided by Intel wasn’t particularly user-friendly, but it worked well enough and included several example applications I could use to test performance. I found that face detection was possible with my webcam in near real-time (something like 19 FPS), and pose detection at about 3 FPS. So in accordance with the holiday spirit, it knows when I am sleeping, and knows when I’m awake.

That was promising, but the NCS2 was marketed as allowing AI processing on edge computing devices. I set about installing it on the Raspberry Pi 3 Model B+ and compiling the application samples to see if it worked better than previous methods. This turned out to be more difficult than I expected, and the main goal of this article is to share the process I followed and save some of you a little frustration.

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Raspberry Pi Counts Down To The Last Bitcoin

January 31, 2019 by 15 Comments

Even though it might appear to be pretend Internet money, by design, there are a finite number of Bitcoins available. In the same way that the limited amount of gold on the planet and the effort required to extract it from the ground keeps prices high, the scarcity of Bitcoin is intended to make sure it remains valuable. As of right now, over 80% of all the Bitcoins that will ever exist have already been put into circulation. That sounds like a lot, but it’s expected to take another 100+ years to free up the remaining ones, so we’ve still got a way to go.

Even though his device will probably no longer exist when the final Bitcoin hits the pool, [Jonty] has built a ticker that will count down as the final coins get mined from the digital ground. The countdown function is of course a bit tongue-in-cheek, but the gadget also shows slightly more pertinent information such as the current Bitcoin value, so you can always remember what a huge mistake it was not to invest while they were still worth pennies.

On the hardware side, this is a pretty simple project. The enclosure is laser cut 5 mm MDF, and it holds a Raspberry Pi 3, a MAX7219 32×8 LED dot matrix display, and a 10 mm white LED with accompanying resistor. The white LED is placed behind an acrylic diffuser to give the Bitcoin logo on the side of the display a soft pleasing glow when the device is powered up. There are no buttons or other controls on the ticker, once the software has been configured it just gets plugged in and away it goes.

As for the software, it takes the form of a Python script [Jonty] has created which uses Requests and Beautiful Soup to scrape the relevant data from bitcoinblockhalf.com. The script supports pulling any of the 19 variables listed on the site and displaying it on the LED matrix, which range from the truly nerdy stats like daily block generation to legitimately useful data points that anyone with some Bitcoin in their digital wallets might like to have ticking away on their desks.

The first decade of Bitcoin has been a pretty wild ride, not only monetarily, but in the wide array of hardware now involved in cryptocurrency mining and trading. From Bitcoin traffic lights to custom-made mining rigs that are today more useful as space heaters, it takes a lot of hardware to support these virtual coins.

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