EMG Tutorial Lets You Listen to Your Muscles

What with wearable tech, haptic feedback, implantable devices, and prosthetic limbs, the boundary between man and machine is getting harder and harder to discern. If you’re going to hack in this space, you’re going to need to know a little about electromyography, or the technique of sensing the electrical signals which make muscles fire. This handy tutorial on using an Arduino to capture EMG signals might be just the thing.

In an article written mainly as a tutorial to other physiatrists, [Dr. George Marzloff] covers some ground that will seem very basic to the seasoned hacker, but there are still valuable tidbits there. His tutorial build centers around a MyoWare Muscle Sensor and an Arduino Uno. The muscle sensor has snap connectors for three foam electrodes of the type used for electrocardiography, and outputs a rectified and integrated waveform that represents the envelope of the electrical signal traveling to a muscle. [Dr. Marzloff]’s simple sketch just reads the analog output of the sensor and lights an LED if it detects a muscle contraction, but the sky’s the limit once you have the basic EMG interface. Prosthetic limbs, wearable devices, diagnostic tools, virtual reality — the possibilities are endless.

We’ve seen a few EMG interfaces before, mainly of the homebrew type like this audio recorder recruited for EMG measurements. And be sure to check out [Bil Herd]’s in-depth discussion of digging EMG signals out of the noise.

Commodore Home – Your Smart Home For 1983

The Internet of Things is a horrific waste of time, even though no one knows exactly what it is. What would make it better? Classic Commodore gear, of course. Now you can run your smart home with a Commodore 64 and Commodore Home, the newest smart home framework from [retro.moe].

Commodore Home comes with the standard smart home features you would expect. The home lighting solution is a dot matrix printer, a few gears, and string tied to the light switch. Activate the printer, and the lights turn on and off. Brilliant. Multiple light switches can be controlled by daisy chaining printers.

Security is important in the smart home, and while the intruder alarm isn’t completely functional, future versions of Commodore Home will dial a modem, log into a BBS, and leave a message whenever an authorized person enters your home.

All of this is possible thanks to advances in UniJoystiCle technology, also from [retro.moe]. This device takes a standard ESP8266 WiFi module and turns it into a smartphone-to-joystick port bridge for the Commodore 64.

Unlike every other piece of IoT hardware being sold today, Commodore Home won’t stop working when the company behind it goes belly up; Commodore has been dead for twenty years already. You can grab all the software for Commodore Home over on the Githubs, or you can check out the video below.

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Hackaday Links: November 20, 2016

The Raspberry Pi 2 is getting an upgrade. No, this news isn’t as big as you would imagine. The Raspberry Pi 2 is powered by the BCM2836 SoC, an ARM Cortex-A7 that has served us well over the years. The ‘2836 is going out of production, and now the Raspberry Pi foundation is making the Pi 2 with the chip found in the Raspberry Pi 3, the BCM2837. Effectively, the Pi 2 is now a wireless-less (?) version of the Pi 3. It still costs $35, the same as the Pi 3, making it a rather dumb purchase for the home hacker. There are a lot of Pi 2s in industry, though, and they don’t need WiFi and Bluetooth throwing a wrench in the works.

So you’re using a Raspberry Pi as a media server, but you have far too many videos for a measly SD card. What’s the solution? A real server, first off, but there is another option. WDLabs released their third iteration of the PiDrive this week. It’s a (spinning) hard disk, SD card for the software, and a USB Y-cable for powering the whole thing. Also offered is a USB thumb drive providing 64 GB of storage, shipped with an SD card with the relevant software.

Mr. Trash Wheel is the greatest Baltimore resident since Edgar Allan Poe, John Waters, and Frank Zappa. Mr. Trash Wheel eats trash, ducks, kegs, and has kept Inner Harbor relatively free of gonoherpasyphilaids for the past few years. Now there’s a new trash wheel. Professor Trash Wheel will be unveiled on December 4th.

YOU MUST VOICE CONTROL ADDITIONAL PYLONS. With an ‘official’ StarCraft Protoss pylon and a Geeetech voice recognition module, [Scott] built a voice controlled lamp.

Everyone loves gigantic Nixie tubes, so here’s a Kickstarter for a gigantic Nixie clock. There are no rewards for just the tube, but here’s a manufacturer of 125mm tall Nixies.

Here’s an interesting think piece from AdvancedManufacturing.org. The STL file format is ancient and holding us all back. This much we have known since the first Makerbot, and it doesn’t help that Thingiverse is still a thing, and people don’t upload their source files. What’s the solution? 3MF and AMF file formats, apparently. OpenSCAD was not mentioned in this think piece.

MIDI Guitar Pedals

Ever since Jimi Hendrix brought guitar distortion to the forefront of rock and roll, pedals to control the distortion have been a standard piece of equipment for almost every guitarist. Now, there are individual analog pedals for each effect or even digital pedals that have banks of effects programmed in. Distortion is just one of many effects, and if you’ve built your own set of pedals for each of these, you might end up with something like [Brian]: a modular guitar pedal rack.

ae0fmjxTaking inspiration from modular synthesizers, [Brian] built a rack out of wood to house the pedal modules. The rack uses 16U rack rails as a standard, with 3U Eurorack brackets. It looks like there’s space for 16 custom-built effects pedals to fit into the rack, and [Brian] can switch them out at will with a foot switch. Everything is tied together with MIDI and is programmed in Helix. The end result looks very polished, and helped [Brian] eliminate his rat’s nest of cables that was lying around before he built his effects rack.

MIDI is an extremely useful protocol for musicians and, despite being around since the ’80s, doesn’t show any signs of slowing down. If you want to get into it yourself, there are all kinds of ways that you can explore the studio space, even if you play an instrument that doesn’t typically use MIDI.

Bringing USB Devices To The Apple Desktop Bus

During the development of the greatest member of the Apple II family, the Apple IIgs, someone suggested to [Woz] that a sort of universal serial bus was needed for keyboards, mice, trackballs, and other desktop peripherals. [Woz] disappeared for a time and came back with something wonderful: a protocol that could be daisy-chained from keyboard to a graphics tablet to a mouse. This protocol was easily implemented on a cheap microcontroller, provided 500mA to the entire bus, and was used for everything from license dongles to modems.

The Apple Desktop Bus, or ADB, was a decade ahead of its time, and was a mainstay of the Mac platform until Apple had the courage to kill it off with the iMac. At that time, an industry popped up overnight for ADB to USB converters. Even today, there’s a few mechanical keyboard aficionados installing Teensies in their favorite input devices to give them a USB port.

While plugging an old Apple keyboard into a modern computer is a noble pursuit — this post was written on an Apple M0116 keyboard with salmon Alps switches — sometimes you want to go the other way. Wouldn’t it be cool to use a modern USB mouse and keyboard with an old Mac? That’s what [anthon] thought, so he developed the ADB Busboy.

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Scrap Bin Mods Move Science Forward

A first-time visitor to any bio or chem lab will have many wonders to behold, but few as captivating as the magnetic stirrer. A motor turns a magnet which in turn spins a Teflon-coated stir bar inside the beaker that sits on top. It’s brilliantly simple and so incredibly useful that it leaves one wondering why they’re not included as standard equipment in every kitchen range.

But as ubiquitous as magnetic stirrers are in the lab, they generally come in largish packages. [BantamBasher135] needed a much smaller stir plate to fit inside a spectrophotometer. With zero budget, he retrofitted the instrument with an e-waste, Arduino-controlled magnetic stirrer.

The footprint available for the modification was exceedingly small — a 1 cm square cuvette with a flea-sized micro stir bar. His first stab at the micro-stirrer used a tiny 5-volt laptop fan with the blades cut off and a magnet glued to the hub, but that proved problematic. Later improvements included beefing up the voltage feeding the fan and coming up with a non-standard PWM scheme to turn the motor slow enough to prevent decoupling the stir bar from the magnets.

[BantamBasher135] admits that it’s an ugly solution, but one does what one can to get the science done. While this is a bit specialized, we’ve featured plenty of DIY lab instruments here before. You can make your own peristaltic pump or even a spectrophotometer — with or without the stirrer.

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Portable Classroom Upgrade: Smaller, Cheaper, Faster

[Eric] at MkMe Lab has a dream: to build a cheap, portable system that provides the electronic infrastructure needed to educate kids anywhere in the world. He’s been working on the system for quite a while, and has recently managed to shrink the suitcase-sized system down to a cheaper, smaller form-factor.

The last time we discussed [Eric]’s EduCase project was as part of his Hackaday Prize 2016 entry. There was a lot of skepticism from our readers on the goals of the project, but whatever you think of [Eric]’s motivation, the fact remains that the build is pretty cool. The previous version of the EduCase relied on a Ku-band downlink to receive content from Outernet, and as such needed to stuff a large antenna into the box. That dictated a case in the carry-on luggage size range. The current EduCase is a much slimmed-down affair that relies on an L-band link from the Inmarsat satellites, with a much smaller patch antenna. A low-noise amp and SDR receiver complete the downlink, and a Raspberry Pi provides the UI. [Eric]’s build is just a prototype at this point, but we’re looking forward to seeing everything stuffed into that small Pelican case.

Yes, Outernet is curated content, and so it’s not at all the same experience as the web. But for the right use case, this little package might just do the job. And with a BOM that rings up at $100, the price is right for experimenting.

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