Doppler-effect Lets You Add Gestures To Your Computer

March 21, 2012 by Mike Szczys 40 Comments

What if you could add gesture recognition to your computer without making any hardware changes? This research project seeks to use computer microphone and speakers to recognize hand gestures. Audio is played over the speakers, with the input from the microphone processed to detect Doppler shift. In this way it can detect your hand movements (or movement of any object that reflects sound).

The sound output is in a range of 22-80 kHz which is not audible to our ears. It does make us wonder if widespread use of this will drive the pet population crazy, or reroute migration paths of wildlife, but that’s research for another day. The system can even be used while audible sounds are also being played, so you don’t lose the ability to listen to music or watch video.

The screen above shows the raw output of the application. But in the video after the break you can see some possible uses. It works for scrolling pages, double-clicking (or double-tapping as it were), and there’s a function that detects the user walking away from the computer and locks the screen automatically.

[Sidhant Gupta] is the researcher who put the video together. In addition to this project (called SoundWave) he’s got several other interesting alternative-input projects on his research page. Continue reading “Doppler-effect Lets You Add Gestures To Your Computer” →

Software Defined Radio From A USB TV Capture Card

March 20, 2012 by Brian Benchoff 48 Comments

With a simple digital TV USB capture card, you can build your own software defined radio or spectrum analyzer. While it may not be as cool as [Jeri Ellsworth]’s SDR, it’s still very useful and only requires $20 in hardware.

The only piece of hardware required for this build is a USB FM/DTV capture device with the Realtek RTL2832U chipset. So far, two USB sticks have been tested and the unit with the largest frequency range (64 – 1700 MHz) is available direct from China for $20.

Turning these cheap capture cards into software defined radios and spectrum analyzers was discovered by [Antti Palosaari] after sniffing the device. These cards demodulate the frequency and send all the data to the computer and is decoded via software. If you have one of these capture cards lying around, you can grab the software and load it up on your *nix box. Right now, the software only writes directly to a file, and may drop a few samples if writing to a hard disk instead of ram. Small problems, but we’re sure this project will pick up steam in the very near future.

via reddit

Isomorphic Piano Keyboard Is Button Madness

March 19, 2012 by Brian Benchoff 15 Comments

[nikescar] sent in a link to a huge isomorphic MIDI keyboard. We might have missed it the first time around, but that doesn’t diminish such a great looking project.

According to the project page, this humongous keyboard is the work people at Louisville Soundbuilders’ efforts to clone the AXiS-64 MIDI controller. Instead of looking like a ‘normal’ piano keyboard, this isomorphic keyboard puts notes in a hexagonal pattern. This keyboard layout is very useful – fingerings for chords are the same across all keys – but these keyboard layouts are fairly rare and MIDI controllers are expensive as a result.

To make the keyboard in the video velocity sensitive, there are two layers of PCBs. The top layer uses Cherry key switches, while the bottom PCB is an array of tact switches. Measuring the time between the top and bottom key presses gives the on board microcontroller velocity information that is converted to MIDI notes. This setup has a few downsides, namely the huge amount of switches, components, and pins needed for two keyboard matrices.

The project page hasn’t been updated for a few months, so we’re pretty curious about the current status of this build. If any of the Louisville Soundbuilders have an update on this project, send it on in.

Using The Nook As A Keyboard

March 16, 2012 by Brian Benchoff 5 Comments

[Andrew] has been pining for an Optimus Maximus – a keyboard with a small LCD screen in each key – for years. Like a lot of people, he love the idea of a completely configurable keyboard, but balked at the two thousand dollar price tag. Although it doesn’t have full color OLED screens behind each key, [Andrew]’s nook simple touch can be used as a keyboard just the same.

After rooting his new nook, [Andrew] had a very nice tablet computer, and the only Android device with an e-ink screen. Although[Andrew] never wrote an Android app before, he wanted to do a proof of concept build to see if a nook keyboard would actually work. The “keyboard app” is actually just a webpage hosted on his home server. When he presses a virtual key, JavaScript sends an ASCII value back to the server where it is decoded and sent to xte.

[Andrew] says his build works, but not very well. Opera mini doesn’t like the homebrew server he set up, and Cyrillic characters are a no go. Still, it works, and looks like an awesome application for an e-ink tablet with a proper Android app. Demo after the break.

Continue reading “Using The Nook As A Keyboard” →

Foot-controlled Mouse Keeps Your Hands On The Keyboard

March 7, 2012 by Mike Szczys 27 Comments

A bit of mechanical ingenuity makes building this foot-controlled mouse into a fun project. It consists of a platform which hosts one pedal for each foot. The right foot controls the movement of the cursor, and the left is responsible for the buttons.

The guts of a wireless mouse do most of the electrical work for this hack. You can see that the optical sensor is mounted on the front of the right foot pedal. A ball bearing combined with a hinge provides motion on two axes. This moves the sensor past a piece of curved foam made by covering a ball with plastic wrap then spraying foam insulation around it. The pedal on the left has four buttons actuated by moving the toes down, up, left, or right. There’s a centering mechanism for this pedal which uses a rubber band

One thing we wonder about here is whether there is a need to lift and re-center the mouse/cursor? There is also no scroll wheel. But those issues are just waiting for someone to pick up the project and make their own improvements.

Resetting The Page Count On A Laser Printer

March 5, 2012 by Brian Benchoff 101 Comments

[Brian] really liked his Samsung color laser printer right up until it was time to replace the toner cartridges. A full set of toner cartridges sell for about the same price as the printer itself, so [Brian] figured he could simply refill the toner in the cartridges he already has. The printer sends out the ‘low toner’ warning based on page count and won’t print if the page count is too high, negating the economy of a toner refill kit. Luckily, [Brian] figured out a dead simple way to reset the page count so he can use those third-party refill kits.

All the configuration settings and page counts for the printer are stored on an I2C EEPROM. After dumping the data held on this EEPROM with an Arduino and sniffing everything going into the EEPROM with a Bus Pirate, [Brian] was nearly at his wit’s end. Thankfully, serendipity intervened. When [Brian] restarted the printer with the Bus Pirate attached, he noticed it took much longer to initialize. Printing a configuration report, he was trilled to see that all page counts have been zeroed.

The final hack that allows [Brian] to reset the page count and used refilled toner cartridges is a simple wire that ties the SDA line of the EEPROM to ground on boot. [Brian] used a momentary switch, but given this is a once-every-few-months operation, a simple wire would suffice. Check out [Brian]’s page reset demo after the break.

Continue reading “Resetting The Page Count On A Laser Printer” →

Control Your PC With A Remote

March 5, 2012 by Brian Benchoff 16 Comments

Because his computer is gradually turning into an all-inclusive media display device, [Shawn] figured a remote to control the volume and a video playlist would be a reasonable addition. TV remotes for computers have been around for years, but [Shawn] decided to go the DIY route and build his own computer remote.

For the build, [Shawn] used a Teensy dev board with an IR receiver module and the requisite infrared remote library. To translate infrared signals to keyboard commands,[Shawn] decided to base his project off a previous build that used a small program called AutoHotKey.

Right now the build can cycle through a pre-defined YouTube and Shoutcast playlist and change the volume of the currently playing track. There’s also support for moving the mouse with directional buttons on the remote, but we’re wondering if a better implementation would be using the Windows multimedia keyboard scan codes that should be supported by [Shawn]’s laptop.

Still, [Shawn] managed a very nice build that would fit into our computer battlestations quite nicely. Check out the demo of the remote in action after the break.

Continue reading “Control Your PC With A Remote” →