This project is in one of our favorite categories; the kind where asking “why?” is the wrong question. [Berto A.] built the device after observing some power generation by placing a large magnet next to a mechanical relay coil and quickly clicking the relay’s lever. From this humble beginning he built up the RattleGen, a bicycle spoke driven generator.
To get the most power possible he searched around for a massive relay and found one which was originally meant for telephone exchanges. He cut the case open and strapped a big bar magnet to the side of the coil. Next he fabricated an arm which will press against the relay’s lever. To that he added a small wheel which is pressed each time a spoke from the bicycle passes by it. This repeated clicking of the relay lever generates a current (and a rattling sound) that is harvested by the joule thief circuit built on some protoboard. An LED is illuminated, with excess current stored in the capacitor bank. Don’t miss the build and demonstration video after the break.
We love looking at roll-your-own wristwatch projects. Getting a project small enough to carry around on your wrist is a real challenge. But we think the OTM-02 wristwatch really hit the form factor right on the mark.
OTM stands for Open source Time Machine. It’s the work of [Hairy Kiwi] and he managed to bring the guts of the watch in at a thickness between 6.5 and 7mm. That includes the LCD, PCB, piezo diaphragm, and the battery. The PCB itself is a four-layer board built on 1mm thick substrate. It’s running an EFM32 (ARM) microcontroller which comes with hardware USB support. The little door sitting open on the side of the 3D printed enclosure provides access to the micro USB connector which can be used to charge the 150 mAh battery inside. That may not sound like much juice, but if you set the display to show minutes only [Hairy] calculates a battery life approaching 175 days. If you just have to have the seconds displayed you can expect about two weeks between charges.
Continuing with our series of best and worst portrayals of hacking, we’re gathering our resources to bring you the top 10 Hacking Documentaries. Again, we feel the strongest resource is the hacking community, so lets hear what you think should qualify. While it would be fantastic to only have documentaries, if there is a hollywood movie that you feel fits, go ahead and let us know. If you’re up for a challenge, find us something dealing with hardware hacking instead of computers/phones!
We laughed when we heard that he removed about eighty pounds of original electronics from this beast. He then cut a piece of MDF to serve as a mounting platform for the replacement hardware. The WiFi router takes care of audio playback from several sources and offers him the ability to control the stereo from a smart phone or a computer. It has a USB port to which he connected a hub to make room for the USB sound card and a thumb drive which holds his music library. The black box in the upper right is an amp which feeds the NHT stereo speakers housed in the lower half of the cabinet.
It doesn’t make use of the original knobs like the recent tube-amp conversion we looked at. But [Craig] did add some LEDs which illuminate the dial to help keep that stock look.