Month: January 2011

Nokia Internet Key External Antenna

January 17, 2011 by 13 Comments

[Maurizio] was having some reception issues with his wireless internet and set out to add an external antenna to the USB dongle (translated). He had previously poked around inside of the Nokia internet key to find that the internal antenna was a flexible circuit substrate wrapped around a plastic box that made contact with main circuit board via a spring connector. This plastic frame is just right for mounting an SMA connector in just the right place for it to stick out the end of the case as seen in the picture above. It gives him better range, but since speed depends on how much traffic the wireless node is under, it’s not a guarantee that you’ll get a snappier connection after this hack.

Tri-rotor Helicopter With Full Autopilot

January 17, 2011 by 17 Comments

Quadcopters stand aside, here’s a three-rotor helicopter we think you’re going to love. The body is made out of plywood and carbon fiber rods, keeping it light enough to be easily lifted by just 3 motors while making sure the force doesn’t tear the aircraft apart. Three gyroscopes, two accelerometers, three magnetometers, and a GPS module are all used in conjunction for an autopilot system. There’s a lot of great pictures and videos but our favorite, embedded after the break, shows the tricopter writing messages in the sky using light and camera exposure tricks similar to this ground-based trike.

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Is Your Camera Lying?

January 17, 2011 by 25 Comments

It is easy to rely on the ratings marked on different tools, whether it is a power supply, scale, or speedometer. However calibration is essential for any part that is relied upon either professionally or for a hobby. [Jeremy] wanted to see if his Lomography camera shutter really was only open for 1/100ths of a second when set to that. In order to test his rig, he set up an LED on one side of the shutter, and a high speed phototransistor to gauge the time spent open, using an oscilloscope to measure the time the reference point was pulled low. In his case, when the camera was set to 1/100, the shutter was actually open for closer to 1/150th of a second (the mean was 1/148ths of a second, with a standard deviation of 417 uSecs). This difference can make a large difference in picture brightness.

Be sure to check his blog for more pictures of the setup, as well as some useful part references and circuit diagrams.

Audio Crossover Back In Service

January 17, 2011 by 24 Comments


Audio Crossovers are an essential tool for any high end speaker system. Because most individual loudspeakers are unable to cover the entire spectrum of audible sound as well as multiple drivers are, it is necessary to split the input signal into low and high frequency parts. When a friend of [Anthony]’s was about to send off a classic Klipsch AA Crossover to be repaired professionally, [Anthony] insisted it was possible to save some money and do it himself.

The oil can capacitors of the Crossover had gone bad, so a new set of metalized polypropylene capacitors were ordered to pick up the task. After carefully removing the old caps, [Anthony] assembled the new set on a breadboard, and mounted the board to the old Crossover base (along with some tasteful McDonalds straw spacers). The entire process is detailed on his blog, and we are sure his friend saved a good deal by this home repair method. Capacitor issues are a common problem in repairing electronics new and old alike, and always a great place to start looking when devices start acting funny.

Electronic Dice Has Option For 20 Or 100 Sides

January 17, 2011 by 17 Comments

[Bluewraith] built himself an electronic dice using a 555 timer and 4017 counter. This is a classic project and he enjoyed doing it but wondered about making a 20-sided dice. So he grabbed his Arduino and got to work. A switch on the final project selects between 20 or 100 sides. He used a MAX7219 to control the 7-segment displays, and a standalone AVR chip for the rest of it.

If you missed it back in October you should also look in on this 6-sided dice. It also uses an AVR running the Arduino bootloader but a mercury switch allows the player to shake the box in order to start a roll.

One last note, we made a conscious decision to use the word ‘Dice’ instead of the grammatically correct ‘Die’ which is its singular version. We think ‘Die’ can be a bit too confusing and we’re not the only ones.

Electrodes Turn Your Eyelids Into 3D Shutter Glasses

January 16, 2011 by 153 Comments

[Jonathan Post] has a way to watch 3D video without wearing shutter glasses but it might be kind of a hard product to break into the market. As you can see above, a pair of electrodes are stuck on a viewer’s eyelids, using electricity to alternately close each eye. The video after the break shows a demonstration of this technology. Obviously a camera can’t capture the image that the viewer sees, but this man describes a perfect 3D image. This reminds us of those ab exercisers that use electrodes to stimulate the muscles. Do you think a 3 hour epic would leave your eyelids tired and sore, eventually resulting and a steroid-esque muscle-ridden face?

Edit from [Caleb]: Judging from the comments, some people believe this to be an absolute impossibility. While we concur that this example is pretty silly (what’s powering those electrodes?), we invite you to watch [Daito Manabe]’s facial electrodes fun.

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$20 Fuel Injector Tester

January 16, 2011 by 39 Comments

[Dino] is an auto mechanic and needed a way to test out fuel injectors. Commercially available tools start well over $100 and go up from there, but he built his own for about $20.

The injectors have a coil in them that needs to be tested. His design calls for a series of 0.008 millisecond pulses to test the coil. He started by setting up a 555 timer to output a one second pulse. This signal is fed into a second 555 chip that outputs the 0.008 pulses and in turn actuates a MOSFET to switch the coil on and off. To use it [Dino] connects to a 12V bench supply and to the injector, using a single button to start the test. See him explain the setup in the video after the break.

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