[Matt the Gamer] loved his pair of Minimus 7 bookshelf speakers. That is until a tragic hacking accident burned out the driver and left him with a speaker-shaped paper weight. But the defunct audio hardware has been given new life as a single portable powered speaker. Now he can grab it and go, knowing that it contains everything he needs to play back audio from a phone or iPod.
The most surprising part of the build is the battery. [Matt] went with a sealed lead-acid battery. It just barely fits through the hole for the larger speaker, and provides 12V with 1.2 mAh of capacity. He uses an 18V laptop power supply when charging the battery. The PSU is just the source, his own circuit board handles the charging via an LM317 voltage regulator. Also on the board is an amplifier built around a TDA2003A chip. He added a back panel which hosts connections for the charger and the audio input. Two switches allow the speaker to be turned on and off, and select between battery mode and charging mode. As a final touch he added a power indicator LED to the front, and a drawer pull as a carrying handle.
It should come as no surprise that the guys behind the advance electric racer aren’t doing this sort of thing for the first time. A couple of them were involved in Formula Hybrid Racing at the University of Wisconsin. That experience shows in the custom motor controller built as an Arduino shield. It includes control over acceleration rate, throttle response, and regenerative braking. But you can’t get by on a controller alone. The motors they used are some special electric garden tractor motors to which they added their own water cooling system.
If you want to get a good look at how fast and powerful this thing is head on over to the post about the KC leg of PPPRS (it’s the one towing a second vehicle and still passing the competition by).
I had an idea for keeping things interesting on this long road trip through the southwest. I was going to gather a few bits from each hackerspace and build something using minimal tools while we were driving down the road. I settled on the idea of a really simple “jailhouse” tattoo gun. I knew I could build one from parts I could source very easily and that I wouldn’t need much in terms of tools to make it happen.
Many people with hearing impairments have assistive devices at home that flash a light whenever a fire truck goes by, an alarm bell goes off, or the doorbell rings. With the exception of a hearing dog, these devices are useless outside the home, and this is where [Halley]’s Flutter dress comes into play. Flutter has microphones and microcontrollers sewn into the dress to listen to the surrounding environment and uses small vibration motors to wave small cloth leaflets whenever a loud sound is detected.
In the writeup for Flutter (PDF), [Halley] tells us she used a quartet of microcontrollers to detect the ambient acoustic environment. Each microcontroller passes the signal from the microphone into a buffer where it performs an FFT on the sound data. From this, the loudness and frequency of a noise – as well as the direction from a time-of-flight calculation – can be determined. Once that is complete, each microcontroller actuates a small vibrator motor in the dress’ leafs according to how loud and in which direction the sound came from.
As with all assistive technologies for the hearing impaired, there is always the aspect of deaf culture’s point of view that such inventions are seen as forcing a disability on someone. [Halley]’s Flutter dress was with the input of a few family members who have hearing impairments and got some positive feedback from members of the community. Good job, and we can see why it won Best in Show at the 2012 International Symposium on Wearable Computer’s Design Exhibition.
What better way to spend a few months in the workshop than by heating Copper chloride to 400° C, building rotary spark gaps and 30kV capacitors, playing with high vacuums and building a very powerful laser? It’s just a day in [Jon]’s life as he builds a DIY Copper vapor laser.
Copper vapor lasers require temperatures of about 1500° C, but this is only when using pure Copper. Compounds such as Copper chloride are able to bring the required temperatures for lasing down to about 400° C, a reasonable temperature for [Jon]’s home built laser tube furnace. The only problem with this setup is the requirement for two electrical pulses, one to disassociate the Copper and a second to make the Copper lase.
The professional way of creating these electrical pulses would be a Thyratron, but it seems [Jon] wanted something cooler. He built a rotary spark gap out of two 2 inch thick blocks of acrylic that allow him to perfectly time the frequency and separation of the electrical pulses needed for his laser.
There is no word on exactly how much power [Jon]’s Copper vapor laser will put out when it’s complete, but [Jon]’s build log is already an amazing display of awesome. You can check out a short video showing off [Jon]’s laser, spark gap, and huge home-made capacitor after the break.
While on our southwest tour, we were sure to make some time to go visit [Mikey Sklar]. He’s been a friend of hackaday for a long time, both as a writer and as someone who sends us cool projects. As you may have noticed from some of the posts we’ve done on his projects, [Mikey] lives in the middle of the desert and is attempting to lead a fairly self sustaining life style. He and [Wendy] showed us their gardens, the hot spring on their property,and some cool building materials they’ve utilized. We got to tour [Mikey’s] workshop and check out how his solar system was set up. It was pretty cool seeing “da Pimp” being used to revive old batteries. [Mikey] even mentioned that he’s building in a lot of safeguards in the next revision based on the feedback he got online.
What I really enjoyed about talking with [Mikey] and [Wendy] was that they didn’t act like they had it all figured out. They’re approaching this whole lifestyle as a learning adventure as you can hear when [Mikey] talks about their bees.
Fresh from Microsoft Research is an ingenious way to reduce interference and decrease the error in a Kinect. Bonus: the technique only requires a motor with an offset weight, or just an oversized version of the vibration motor found in a pager.
Being the first of its kind of commodity 3D depth sensors, the tracking on a Kinect really isn’t that good. In every Kinect demo we’ve ever seen, there are always errors in the 3D tracking or missing data in the point cloud. The Shake ‘n’ Sense, as Microsoft Research calls it, does away with these problems simply by vibrating the IR projector and camera with a single motor.
In addition to getting high quality point clouds from a Kinect, this technique also allows for multiple Kinects to be used in the same room. In the video (and title pic for this post), you can see a guy walking around a room filled with beach balls in 3D, captured from an array of four Kinects.
This opens up the doors to a whole lot of builds that were impossible with the current iteration of the Kinect, but we’re thinking this is far too easy and too clever not to be though of before. We’d love to see some independent verification of this technique, so if you’ve got a Kinect project sitting around, strap a motor onto it, make a video and send it in.