Will Dance For Bitcoin

December 7, 2013 by 6 Comments

It seems that Bitcoin is all over the news nowadays, but the Bitcoin Bot is probably the first robot that will dance for Bitcoins.

[Ryan] at HeatSync Labs in Mesa, AZ, is a fan of the cryptocurrency, and decided to build something to accept it. He discovered that Coinbase, a popular hosted Bitcoin wallet service, has a callback API. This causes Coinbase to fetch a specified URL any time a wallet receives a transaction, and provides information on the transaction in the request. A Python script handles these requests and updates a running count of the BTC balance sent to the robot’s wallet.

On the hardware side, an Arduino with an Ethernet Shield checks the balance. If it has changed, it calls the dance function and the luau girl dances.

The robot sits in the window of the hackerspace, so anyone passing by can read about Bitcoin and make a donation. The source code is on Github, and a video follows after the break.

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Super Simple FM Transmitter

December 7, 2013 by 29 Comments

Making your own FM radio is practically a rite of passage for hackers. How about making a small FM transmitter?

Originally designed by the Japanese multimedia artist [Tetsuo Kogawa], this simple FM transmitter can be built with only 10 components and about an hour of your time. The method shown here is one of the easiest to build, and it’s called the Manhattan Style — the same method used when [Bill Meara] built his BITX radio. It’s unique in that instead of using traces it uses one copper PCB which is used for all ground connections, and then small islands of the same PCB glued on top to form nodes for the circuit to connect to. Besides being an extremely easy way to make a PCB without any fancy tools, it also makes you think about circuits in a different light. In fact, it gives “floating ground” a whole new meaning!

While its 10 component count is impressive, it can’t beat this 3 component FM transmitter we shared a year ago! Stick around after the break to see how to make your very own.

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Repairing Bose Active Noise Cancelling Headphones

December 7, 2013 by 51 Comments

[Mansour] was disappointed to find out that his Bose QC15 headphones had a dead right channel. These headphones have active noise cancelling, which uses a microphone to capture ambient noise and digital signal processing to insert an out of phase signal. Since they’re quite expensive, [Mansour] was determined to resurrect them.

First, he determined that the right speaker had died, so he found a replacement on eBay. These were designed for a different set of headphones, but matched the impedance of the original Bose part. After replacing the driver, it seemed that the repair was a failure. The sound cancelling wasn’t working, and a the playback was high-pitched. As a last attempt, he potted the speaker with glue, to match the original construction. Much to his surprise, this worked.

The problem was that the new driver didn’t have sufficient sound isolation from the microphone, which is meant to pick up passive noise. This feedback likely caused issues with the noise cancelling DSP. A little glue meant a $20 fix for a $400 pair of headphones.

Speeding Up BeagleBone Black GPIO A Thousand Times

December 7, 2013 by 42 Comments

For both the Raspberry Pi and BeagleBone Black, there’s a lot of GPIO access that happens the way normal Unix systems do – by moving files around. Yes, for most applications you really don’t need incredibly fast GPIO, but for the one time in a thousand you do, poking around /sysfs just won’t do.

[Chirag] was playing around with a BeagleBone and a quadrature encoder and found the usual methods of poking and prodding pins just wasn’t working. By connecting his scope to a pin that was toggled on and off with /sysfs he found – to his horror – the maximum speed of the BBB’s GPIO was around three and a half kilohertz. Something had to be done.

After finding an old Stack Overflow question, [Chirag] hit upon the solution of using /dev/mem to toggle his pins. A quick check with the scope revealed he was now toggling pins at 2.8 Megahertz, or just about a thousand times faster than before.

Using XBox One And PS4 Controllers With Everything

December 7, 2013 by 22 Comments

The controllers from the last generation of consoles served their purpose well. They were there for us when we wanted to experiment with an I2C bus, and they stood by when we wanted to build a quadcopter out of parts just lying around. A new generation of consoles is now upon us, and with them come new controllers. Controllers for which Arduino libraries haven’t been written yet. The horror.

Until those libraries are developed, there’s ChronusMAX, a USB dongle that allows you to use XBox One controllers on a PS4, PS4 controllers on the XBox, mice and keyboards on both systems, and both types of controllers on your PC.

The folks behind ChronusMAX put up a video demoing the XBox One controller working on the 360, PS3, and PC, with another video showing the same for the PS4 controller. As far as what we can see from the PC demos, everything on these controllers can be read, right down to the accelerometer data on the DualShock 4.

Although this is a commercial product, we’re surprised we haven’t seen a more open version by now. From the looks of it, it’s a very small device with two USB ports and a firmware upload utility. Microcontrollers with two native USB ports are usually encased in large packages, so there might be some very clever engineering in this device. Let us know when someone does a teardown of one of these.

Thanks [Josh] for sending this one in.

A Rostock Welding 3D Printer?

December 7, 2013 by 65 Comments

Tired of printing in boring old plastic? Why not try metal? Researchers at Michigan Tech have come up with an open source reprap style design of a 3D printer that can print metal for only $1200.

The paper was published in IEEE Access a few weeks ago that it outlines the design and testing of this printer, which is basically an upside down Rostock with a MIG welder used as the extruder. As you can imagine, the quality and resolution of the parts isn’t that amazing (hang around after the break to see an example), but this is an exciting step forward for 3D printing. Equipped with this and a mill and the possibilities are quite endless!

Did we mention how cheap welding wire is? A cost that could add up is the shielding gas though, but as a user on Reddit points out, an upgrade for this machine could be an enclosed build chamber which could then just be flooded with the gas. Alternatively, would flux-core welding wire work?

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Raspi AC And Blinds Controller

December 7, 2013 by 10 Comments

raspiBlindsACController

[Chris’s] bedroom has a unique setup with an air conditioning unit perched on the wall next to the top of the blinds that cover his window. Normally, to open the blinds he had to tug on a cord and operating the AC meant fiddling with a remote control. Not anymore. Now [Chris] has an all-in-one Raspberry Pi-based solution to drive both.

The build uses a stepper motor salvaged from a printer to directly drive the blinds, with a familiar-looking Easy Driver connecting it to the Pi. The motor spins the blinds’ mechanism either open or closed, though at a modest pace that’s slow enough to provide the needed torque. [Chris] added an IR diode plugged into the Pi that imitates the air conditioning unit’s remote control, and simply pointed it directly at the unit’s receiver. An inexpensive WiFi dongle gets the Pi onto the network, allowing [Chris] to interact via a custom web interface. The interface itself not only provides a couple of clickable buttons, but a cleverly-designed status image indicating the position of the blinds.

Make sure you see the video below for a demonstration and for more details on the build. This is one of the better examples of home automation devices we’ve seen recently, especially considering it actually fits the “autonomous” implications discussed in our Ask Hackaday post from a few months back—although a relatively simple automation, [Chris’s] interface does allow for operating both the blinds and the AC on a preselected schedule.

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