Electronic Bike Derailleur

June 6, 2012 by 38 Comments

[Nabil] sent in an awesome electronic bicycle derailleur. Now, instead of pulling a steel cable with a shifting mechanism, [Nabil] can change gears electronically. As a bonus, the derailleur can be controlled by a small bicycle computer, so he’s always in the right gear.

The new electronic derailleur is controlled by a pair of servos with push buttons in the handle bar. This allows [Nabil] to automatically trim his chain, completely eliminating chain rub.

This electronic shifter is part of [Nabil]’s much large bike computer project. In addition to electronic control of what gear the bike is in, [Nabil] will be adding a GPS, accelerometer, an altimeter and a heart rate monitor and pulse ox meter. That’s an impressive bit of kit, and we cant wait to see the entire project finished. You can pick up the current version of the design over on GitHub and follow all the updates on [Nabil]’s blog.

Outdoor Stereo Helps Your Neighbors Learn To Issue Noise Complaints

June 6, 2012 by 23 Comments

Backyard parties are going to rock over at [Effin_dead_again’s] house. That’s because he just finished building this outdoor stereo. It carries its own power supply so you can take it on the road with you, and we don’t think you’ll have trouble hearing it with the 240 Watt amplifier hidden inside.

He shared the equipment details in his Reddit conversation. A 12V lawn mower battery sits in the base of the wooden enclosure. One of the commenters mentioned the dangers of hydrogen off-gassing from that power source, but [Effin_dead_again] thought of that and included venting around the lid. The subwoofer is an 8″ Alpine, and speakers are out of a Hyundai car. The head unit has Bluetooth built in for easy connection to your smart phone. It of course has the ability to play CDs and MP3s too, and we’d bet you can tune the radio if there’s an antenna connected.

Need similar power but a bit more portability? Check out this stereo built into a cooler.

Arduino Rover Doubles Up On Obstacle Avoidance

June 6, 2012 by 6 Comments

[Eduard Ros] wrote in show off his first attempt at building an autonomous rover (translated). As with many of these projects, he started with the base of a remote control toy truck. This solves so many mechanical issues, like steering, locomotion, and power source.

He just needed a way to control the vehicle. The recent LayerOne badge hacks either did this through the wireless controller protocol or by adding an Arduino directly to the vehicle. [Eduard] chose the latter, and also included obstacle avoidance sensors in the process. We’ve seen quite a few that use these ultrasonic rangefinders. He decided to go a different route by adding two of them rather than scanning by mounting one on a servo motor.

The video after the break shows the vehicle successfully navigating through a tight space. This makes us wonder how much data can be processed from the stationary sensors? We’re not familiar with how wide the horizontal sensitivity is on the devices. If you have some insight, please share you knowledge in the comments section.

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Retrotechtacular: The Mother Of All Tech Demos

June 5, 2012 by 30 Comments

Most bits of a computer we take for granted today – the mouse, hypertext, video conferencing, and word processing – were all invented by one team of researchers at Stanford in the late 60s. When the brains behind the operation, [Douglas Engelbart], showed this to 1000 computer researchers, the demo became known as The Mother of all Demos. Luckily, you can check out this demo in its entirety on YouTube.

Even though [Englebart]’s demo looks incredibly dated today, it was revolutionary at the time. This was the first demonstration of the computer mouse (side note: they call the cursor a ‘bug’), a chorded keyboard, and so many other technologies we take for granted today. During the presentation, [Englebart] was connected to the SDS 940 computer via the on-line system 30 miles away from Stanford. Yes, this pre-ARPANET, what is normally cited as the precursor to the Internet.

Sadly, most of [Englebart]’s researchers became disillusioned with the time sharing /mainframe paradigm shown in this demo. Those researchers wanted a more decentralized means of computing, so they went off to Xerox PARC where they helped create the first personal computers. Still, most of the ideas from 1968, such as the mouse, hypertext, and word processing, were in those little Xerox boxes.

On a more philosophical note, [Englebart] began his demo with the question, “If, in your office, you as an intellectual worker were supplied with a computer display, backed up by a computer that was alive for you all day and was instantly responsive to every action you had, how much value could you derive from that?” In the 44 years since this Mother of all Demos, we’ve gotten to the point where we already have a computer on our desks all day that is able to do any task imaginable, and it certainty improved our quality of life.

There are a few great resources covering the Mother of all Demos, including the Douglas Engelbart Institute’s history page and the Stanford Mousesite. Looking back, it’s not only amazing how far we’ve come, but also how little has actually changed.

Homemade Silicon Carbide LED

June 5, 2012 by 18 Comments

Here’s an LED indicator which was made at home out of a Silicon Carbide (SiC) crystal (Internet Archive Mirror). The concept is simple, but a bit of trial and error goes into getting that tiny amber spot to light up.

The guesswork comes in finding the right piece of crystal. First [KOS] broke it into tiny pieces, then he started poking the chunks with electrified probes to see if he could get some light out of them. Once an active area was found he needed a base for the crystal. The image above shows the two nails which he used. This provides a large mounting area that also acts as a heat sink to make sure the LED won’t burn itself out. There’s a solder blob which he kept molten with his iron until the crystal could be pushed into place. That holds it securely as the pin which serves as the cathode is positioned.

The whole setup is soldered to some protoboard and is ready to use. This is the second time we remember seeing this technique used to fabricate LEDS. The first time was an accident.

Blu-ray CNC Looks Great For Branding And Engraving

June 5, 2012 by 10 Comments

[Nav] got the bug for a tiny little laser cutter. He pulled off the build, and has just finished the second rendition which makes some nice improvements. He’s was hoping for a laser cutter, but we think this really shines when it comes to branding objects like the scrap wood seen above.

This joins a long line of optical drive parts builds. For instance, we saw this plotter that used the lens sleds from some CD-ROM drives. You may think that [Nav] doesn’t need to worry about the Z axis since this is a laser but you’d be wrong. The focal point of the light needs to hit at the right place to cut efficiently, and this is often the trouble with laser cutters. As material is burned away the laser becomes less efficient if you don’t adjust the lens for vertical position. That’s why we think it’s best as an engraver, but the original build writeup for his cutter does show some success cutting letters in dark paper.

Check out a clip of this design being burnt into the wood after the break.

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Open Source Graphics Card

June 5, 2012 by 31 Comments

Even though NVidia and ATI have been open-source friendly for a while now, there still isn’t a true open-source graphics card. [Anton] and [Per] are trying to fix that by building his own graphics card around an FPGA. The project is called ORSoC, and it’s available on opencores.com.

The guys are building the ORSoC graphics card around a Digilent Atlys FPGA dev board. So far, he can draw lines, textured triangles, bitmap or vector fonts, and throw a few 3D meshes up on the screen. This project isn’t intended to run advanced OpenGL or Steam on Linux, but for all the work that into this graphics accelerator, it’s an amazing piece of work.

There are a few demos after the break; a cube rotating in 3D and a demo drawing and translating polygons and a few textures. The ORSoC is a bit slow, but that’s an artifact of the build not being optimized for the FPGA the team is using. If you’d like to test this graphics card, there’s a Git available. As a bonus you don’t even need an FPGA to play around with this project. There’s also a software emulation of all the functions. Very neat.

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