Making Custom 3D Printed Slide Switches

For a little over a year now we’ve been covering the incredible replicas [Mike Gardi] has been building of educational “computers” from the very dawn of the digital age. These fascinating toys, many of which are now extremely rare, are recreated using 3D printing and other modern techniques for a whole new generation to enjoy and learn from.

He’s picked up a trick or two building these replicas, such as this method for creating bespoke slide switches with a 3D printer. Not only does this idea allow you to control a custom number of devices, but as evidenced in the video after the break, the printed slider sounds absolutely phenomenal in action. Precisely the sort of “clunk” you want on your front panel.

Of course, [Mike] doesn’t expect anyone to create this exact switch. He’s designed it as part of his Working Digital Computer (WDC-1) project that he’s documenting on Hackaday.io, so it has a rather specific set of design parameters. But with the steps he outlines in the write-up, you should have no problem adapting the concept to fit your specific needs.

So how does it work? One half of the switch is a track is printed with indents for both reed switches and 6 x 3 mm disc magnets. The other is a small shuttle that itself has spaces for two of the same magnets. When it slides over the reed switches they’re activated by the magnet on one side, while the magnet on the other side will be attracted to the one embedded into the track. This not only gives the switch detents that you can feel and hear while moving it, but keeps the shuttle from sliding off the intended reed switch.

If you like this, you’ll absolutely love his mostly 3D printed binary encoder that we featured recently. With his track record, we’re excited to follow the WDC-1 project as it develops, and thrilled that [Mike] has brought it to Hackaday.io.

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DTMF To Your Computer, With A Gamepad

Though many of us will never have experimented with it, most readers should be familiar with DTMF as the tones used by the telephone system for dialling. If your youth was not misspent mashing 4-4-2-6-4-6-2, 4-4-2-6-4-1 into a keypad, then you haven’t lived!

As you might expect there are a variety of chipsets to handle DTMF, and one of them has been used by [ackerman] in a slightly unusual way. Many desktop computers do not have a convenient array of GPIOs upon which to hang a piece of hardware, but a constant among them is to support some form of gaming controller. Hence he’s taken a commodity joypad and interfaced a MT8870 DTMF decoder to its switch lines with a simple transistor buffer, and is able to pull the resulting information out in the host operating system. So far there are versions for Windows, DOS, Amstrad CPC, Arduino, and even PSX ( the original PlayStation console ).

One might ask why on earth you might want a DTMF input for your desktop PC, but to do so is to miss the point. We are surrounded by computing devices from our mobile phones upwards that do not have any form of interface that can easily be used by our electronic projects, and this serves as an example of how with a bit of ingenuity that can be overcome. It’s a subject we’ve touched upon before, when we asked why people aren’t hacking their cellphones.

Crisp Clean Shortcuts

People always tell us that their favorite part about using a computer is mashing out the exact same key sequences over and over, day in, day out. Then, there are people like [Benni] who would rather make a microcontroller do the repetitive work at the touch of a stylish USB peripheral. Those people who enjoy the extra typing also seem to love adding new proprietary software to their computer all the time, but they are out of luck again because this dial acts as a keyboard and mouse so they can’t even install that bloated software when they work at a friend’s computer. Sorry folks, some of you are out of luck.

Rotary encoders as computer inputs are not new and commercial versions have been around for years, but they are niche enough to be awfully expensive to an end-user. The short BOM and immense versatility will make some people reconsider adding one to their own workstations. In the video below, screen images are rotated to get the right angle before drawing a line just like someone would do with a piece of paper. Another demonstration reminds of us XKCD by cycling through the undo and redo functions which gives you a reversible timeline of your work.

If you like your off-hand macro enabler to have more twists and buttons, we have you covered, or maybe you only want them some of the time.

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Get Your Tweets Without Looking

Head-mounted displays range from cumbersome to glass-hole-ish. Smart watches have their niche, but they still take your eyes away from whatever you are doing, like driving. Voice assistants can read to you, but they require a speaker that everyone else in the car has to listen to, or a headset that blocks out important sound. Ignoring incoming messages is out of the question so the answer may be to use a different sense than vision. A joint project between Facebook Inc. and the Massachusetts Institute of Technology have a solution which uses the somatosensory reception of your forearm.

A similar idea came across our desk years ago and seemed promising, but it is hard to sell something that is more difficult than the current technique, even if it is advantageous in the long run. In 2013, a wearer had his or her back covered in vibrator motors, and it acted like the haptic version of a spectrum analyzer. Now, the vibrators have been reduced in number to fit under a sleeve by utilizing patterns. It is being developed for people with hearing or vision impairment but what drivers aren’t impaired while looking at their phones?

Patterns are what really set this version apart. Rather than relaying a discrete note on a finger, or a range of values across the back, the 39 English phenomes are given a unique sequence of vibrations which is enough to encode any word. A phenome phoneme is the smallest distinct unit of speech. The video below shows how those phonemes are translated to haptic feedback. Hopefully, we can send tweets without using our hands or mouths to upgrade to complete telepathy.

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Hurdy-Gurdy Gets Modernized With MIDI Upgrades

If you’ve never heard a hurdy-gurdy before, you’re in for a treat. Not many people have, since they’re instruments which are uncommon outside of some eastern European communities. Think of a violin that replaces the bow with a hand-cranked wheel, and adds some extra strings that function similar to drones on a bagpipe. The instrument has been around for hundreds of years, but now it’s been given an upgrade via the magic of MIDI.

All of these new features come from [Barnaby Walters] who builds hurdy-gurdys by hand but has recently been focusing on his MIDI interface. The interface can do pitch-shifting polyphony, which allows the instrument to make its own chords and harmonies. It also has a hybrid poly synthesizer, which plays completely different sounds, and can layer them on top of one another. It can also split the keyboard into two instruments, where the top half plays one sound and the bottom half another. It’s an interesting take on an interesting instrument, and the video is definitely worth a look.

The hurdy-gurdy isn’t a commonly used instrument for hacking compared to something like drums or the violin, of course. In fact we had to go back over ten years to find any other articles featuring the hurdy-gurdy, the Furby Gurdy. It was an appropriately named instrument.

Thanks to [baldpower] for the tip!

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Touch Anything And Everything

Powering IoT devices is often a question of batteries or mains power, but in rare exceptions to this rule there is no power supply (PDF Warning). At the University of Wisconsin-Madison and the University of California, San Diego, researchers have gone the extra mile to make advanced backscatter devices, and these new tags don’t need the discrete components we have seen in previous versions. They are calling it LiveTag, and it doesn’t need anything aside from a layer of foil printed or etched on a flexible ceramic-PTFE laminate. PTFE is mostly seen in the RF sector as a substrate for circuit boards.

We have seen some of the wild creations with wifi backscatter that range from dials to pushbuttons. RF backscatter works by modulating the RF signals in which we are continuously swimming. Those radio waves power the device and disrupt the ambient signals, which disruption can be detected by a receiver. With a BOM that looks like a statement more than a list, integration with many devices becomes a cost-effective reality. Do not however broadcast important data because you cannot expect great security from backscatter.

[Via IEEE Spectrum]

ROPS Will Be The Board X86 Robot Builders Are Waiting For

If your robot has outgrown a Raspberry Pi and only the raw computing power of an x86 motherboard will suffice, you are likely to encounter a problem with its interfaces. The days of ISA cards are long gone, and a modern PC is not designed to easily talk to noisy robot hardware. Accessible ports such as USB can have interfaces connected to them, but suffer from significant latency in the process.

A solution comes from ROPS, or Robot on a PCI-e Stick, a card that puts an FPGA on a blazing-fast PCI-e card that provides useful real-world interfaces such as CAN and RS485 and a pile of I/O lines as well as an IMU, barometer, and GPS. If you think you may have seen it before then you’d be right, it was one of the first-round winners of the Open Hardware Design Challenge. They’re very much still at the stage of having an FPGA dev board and working out the software so there aren’t any ROPS boards to look at yet, but this is a project that’s going somewhere, and definitely one to watch.