An Audio Based USB Oscilloscope and Signal Generator for $20

SoundScope

Are you interested in building a 20kHz 2-channel oscilloscope and a 2-channel signal generator for only $20 with minimal effort? Be sure to check out [Jan_Henrik's] Instructable that goes over how to build this awesome tool from a cheap USB audio card.

We have featured tons and tons of DIY oscilloscopes in the past, but this effort resulted in something very well put together while remaining very simple to understand and easy to build. You don’t even need to modify the USB audio card at all. One of the coolest parts of this build is that you can unplug your probe assembly from your USB audio card, and bring it wherever your hacking takes you. After the build, all you need is [Christian Zeitnitz's] Soundcard Oscilloscope program and you are good to go. One of the major downsides that is often overlooked when using an audio based oscilloscope, is that it is “AC coupled”. This means you cannot measure low-frequencies (including DC signals) using a sound card. Be sure to heed [Jan_Henrik's] advice and do not use your built in audio card as an oscilloscope. With no protection circuitry, it is a sure fire way to fry your computer.

What analog projects have you built around an audio interface? We have seen such an interface used for many different applications, including a few fun medical related hacks (be sure to keep safety your first priority). Write in and let us know!

Capacitive Sensing And Old IBM Keyboards

bar

The pen is mightier than the sword, but the IBM Model M keyboard, properly applied, can knock teeth in. There are a few more IBM keyboards even better suited to blunt force trauma – the extremely vintage beam spring keyboards made for terminals and desktop publishers. Being so very old, there’s no easy way to connect these keyboards to a modern system, so when [xwhatsit] wanted to make his work, he needed to build his own controller.

The beam spring keyboards use capacitive switches, and with 122 keys, the usual method of reading capacitance – putting a capacitor in an oscillator – would be far too slow to be of any use in a keyboard. There is another method of reading capacitance: measuring the current going through the capacitive switch. This can easily be accomplished with an LM339 comparator.

[xwhatsit]‘s keyboard controller uses this capacitive sensing circuit to read the four rows of keys, with a few shift registers taking care of the columns. An ATMega32u2 is the brains of the outfit, running LUFA to translate the key presses to USB.

If you’re lucky enough to have one of these ancient keyboards, [xwhatsit] is selling a few over on the usual mechanical keyboard forums. There’s also a controller for the Model F keyboard using the same basic circuit. If you need one just drop him a line or grab the gerbers and roll your own.

 

 

These Trackpad Winamp Visualizations Really Whip the Llama’s Ass

winamp visualizationAs much as we like a good clean Model M specimen, those curly-corded clicky behemoths are somewhat lacking for certain flavors of gaming. There aren’t any blank keys to override, and there sure isn’t a full-color trackpad that you can write apps for. [Gus] has such a keyboard: the Razer Deathstalker Ultimate which features the SwitchBlade UI. He made himself this sweet audio visualizer for it that extends Winamp visualizations to the Switchblade UI.

[Gus]‘s hack is built on the Tiny3D visualization framework. It does what you might expect—reads the visualization values, sets them up for display on the trackpad, and renders them to said trackpad. [Gus] uses some of the 10 programmable keys to change colors on the fly, and the result is pretty awesome. As [Gus] points out, this is just the beginning of what the plugin can do. You’ll need the Razer SDK to get started, and you can get the other ingredients from [Gus]‘s repo. Once you’re done with this, you could try auto-dimming your keyboard backlight.

Of course there are demo videos after the jump. Come on.

[Read more...]

Learning to Reverse Engineer on a Broken Printer

Lexmark Hack

When a Lexmark inkjet printer stopped working, [Mojobobo] was able to claim it as his own. He quickly realized that the machine was flooded with ink and not worth repairing, but that didn’t mean he couldn’t still find a use for it. When he learned that the printer’s firmware was not only upgradable but also unprotected, he knew he should be able to get the printer to do his own bidding.

[Mojobobo] started his journey with the motherboard. The unit still powered up, but it was asking to insert a “duplex module” before it would boot any further. [Mojobobo] first tried to find a way to trick the duplex module sensor, but was unsuccessful. His next step was to search for some kind of serial communications port. He didn’t have an oscilloscope, so instead he used a speaker with a wire probe. In theory, if the wire was pressed against an active serial port, he would be able to hear varying tones through the speaker. Sure enough, he found some interesting tones after probing around some ports next to a “JTAG” label. He looked up some information about the nearby chip and found that it included an SPI bus.

After some internet research, [Mojobobo] learned enough about SPI to have a rough idea of how to use it. Having limited tools available to him, he decided to use his Arduino to try to communicate with the motherboard. After wiring up a simple circuit, (and then re-wiring it) he was able to dump the first 4096 bytes of the motherboard’s boot loader to the Arduino via the SPI interface.

[Mojobobo's] next steps will be to find a faster way to dump the boot loader. At 9600 baud, he grew tired of waiting after three hours. Once he has the full boot loader he intends to search for a way to bypass the duplex sensor and get the board to finish booting. Then he may just use the printer for its scanning functions, or he might find other interesting uses for it.

Eye Tracking With The Oculus Rift

ocu

There’s a lot you can do with eye and gaze tracking, when it comes to interface design, so when [Diako] got his hands on an Oculus Rift, there was really only one thing to do.

Like a few other solutions for eye tracking we’ve seen, [Diako] is using a small camera with the IR filter removed to read the shape and location of an eye’s pupil to determine where the user is looking. This did require cutting a small hole near one of the Oculus’ eye cups, but the internal camera works great.

To get a window to the world, if it were, [Diako] slapped another camera onto the front of the Oculus. These two cameras are fed into the same computer, the gaze tracking is overlaid with the image from the front of the headset, and right away the user has a visual indication of where they’re looking.

Yes, using a computer to know where you’re looking may seem like a rather useless build, but stuff like this is used in research and extraordinarily high tech heads up displays. Although he’s not using the motion tracking on the Oculus, if [Diako] were to do so, he’d have the makings of one of the most powerful heads up displays possible.

[Read more...]

Using A ThinkPad Keyboard Over USB

kbIt doesn’t have buckling springs, Cherry blues, or even the wonderful if forgotten Alps switches, but the keyboard found in ThinkPads has the best keyboard action of any laptop around. They would make a great USB conversion keyboard, but the board to board connector is very hard to find, and no one has yet managed to get the keyboard and track point working as a USB HID device. Until [rampadc] came along, that is.

[Rampadc]‘s keyboard adapter is built for the ThinkPad T60 keyboard, which is shared between the Lenovo T60, T61, Z60, Z61, R400, R500, T400, T500, and X41 laptops, among many others. The connector is an extremely odd proprietary deal, that can be found through the usual channels for about $5 in quantity 100. On top of this, the keyboard doesn’t have a controller – that’s offloaded to the laptop’s main board. The only electronics in this keyboard is just a matrix. Despite all this, [rampadc] managed to create a breakout board with a decade counter and an SPI GPIO expander.

The board [rampadc] made features one of the proprietary connectors, a few chips, and a receptacle for an Arduino Micro. With just a little bit of code, the old keyboard becomes one of the best portable keyboards in existence, and probably a bit cheaper than the official Lenovo USB-bound ThinkPad keyboard.

[rampadc] has a few of the expansion boards available over on Tindie should you want to build your own. It’s only cost-effective if you have one of these T60 keyboards sitting around in a junk pile; not a likely situation because these machines just don’t die.

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Overengineering A USB Hub

hub

Like many of us, I’m sure, [Nick] doesn’t like digging around behind his computer case for a spare USB port and ended up buying a small USB hub for his desk. The hub worked perfectly, but then [Nick] realized an Ethernet port would be a nice addition. And a DC power supply. Then feature creep set in.

What [Nick] ended up building is a monstrosity of a desk hub with two 24V,  5V, 3.3V 50 Watt DC outputs on banana plugs, a five-port USB hub, four-port Ethernet switch, three mains sockets, 32 digital I/Os, UART, SPI, and I2C ports, a 24×4 LCD or displaying DC current usage and serial input, cooling fans, and a buzzer just or kicks.

The case is constructed out of 6mm laser cut acrylic, and the electronics are admittedly a bit messy. That said, this box does seem very useful and even plays the theme from Mario Brothers, as seen in  the video below.

[Read more...]

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