Rattle Generator Is A New Type Of Dynamo For A Bicycle

April 23, 2013 by Mike Szczys 81 Comments

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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.

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Hiding An Inductive Charging Station Inside Furniture

December 2, 2012 by Mike Szczys 16 Comments

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[Tony] wanted to clean up his bedside table by getting rid of the cables used for charging his devices. He accomplished his goal by integrating an inductive charging station inside his furniture.

He chose to go with a product called Powermat. The base station for the device includes two inductive charging areas. [Tony] started by using a router to make a pocket in the underside of this shelf. He mentions that the remaining wood is only 2mm thick to allow for proper transmission. Before gluing the PCB in place he relocated the power jack so that it is still easy to get to. As you can see in the clip after the break, the system works just fine this way.

One note on the forums hosting this content. We must have loaded the thread three or four times when writing the feature and ended up locked out unless we registered. You can get around this by loading the link in a private/incognito browser.

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How A Quarter Shrinker Works

September 28, 2012 by Mike Szczys 43 Comments

This machine is capable of shrinking coins. What you’re looking at is actually a 3D model of the Geek Groups impulse generator, which is called Project Stomper. The model is used to explain how induction shrinks a quarter to the size of a dime.

The grey chamber to the left is a reinforced containment device. It’s a safety feature to keep people in the same room as the Stomper safe from flying particles which may result from the forces this thing can put out. You see, it uses a mountain of magnetic energy to compress the edges of a coin in on itself.

As the video after the break illustrates, the main part of the machine on the right starts off by boosting mains voltage using a microwave oven transformer. This gets the AC to 2000V, which is then rectified and boosted further to get to 6000V DC. This charges three huge parallel capacitors which are then able to source 100,000A at 6 kV. When it comes time to fire, the charge is dumped into a coil which has the coin at its center. The result is the crushing magnetic field we mentioned earlier.

This isn’t a new concept, we featured a different coin crusher build in the early years of Hackaday’s existence.

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Levitating Lightbulb Does It All With No Wires

July 3, 2012 by Mike Szczys 58 Comments

It would be really fun to do an entire hallway of these levitating wireless lights. This a project on which [Chris Rieger] has been working for about six months. It uses magnetic levitation and wireless power transfer to create a really neat LED oddity.

Levitation is managed by a permanent magnet on the light assembly and an electromagnetic coil hidden on the other side of the top panel for the enclosure. That coil uses 300 meters of 20 AWG wire. A hall effect sensor is used to provide feedback on the location of the light unit, allowing the current going to the coil to be adjusted in order to keep the light unit stationary. When working correctly this draws about 0.25A at 12V.

Wireless power transfer is facilitated by a single large hoop of wire driven with alternating current at 1 MHz. This part of the system pulls 0.5A at 12V, bringing the whole of the consumption in at around 9 Watts. Not too bad. Check out [Chris’] demo video embedded after the break.

A similar method of coupling levitation with power transfer was used to make this floating globe rotate.

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Mini Waterproof LED Lanterns Charge Without Wires

June 19, 2012 by Mike Nathan 23 Comments

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If you’re in search of a flashlight that can stand up to the elements, or simply looking for an easy way to spruce up your pool for those hot summer nights, check out these rechargeable PVC LED lights. Inspired by a post in Make: Magazine featuring Indestructible LED Lanterns, [John Duffy] decided to take the project one step further.

While he liked Make’s iteration of the waterproof lantern, he thought it would be best to permanently seal the lights for maximum durability. Not satisfied with a one-use light, he equipped the PVC lanterns with a single rechargeable AA battery, step-up circuitry to drive the LED, and an inductive charging coil.

His floating, waterproof lights sport a slightly bigger footprint than their predecessors to house the extra electronics, but we think that’s more than a fair trade off considering they can be charged wirelessly.

Place your Digikey/Mouser/Jameco orders now and check out [John’s] how-to video – you just might get some of these built in time for the weekend!

[via HackedGadgets]

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Wireless IPod Charger Built From Scratch

May 10, 2012 by Mike Szczys 20 Comments

Despite the obvious use of a lot of wire, this project is actually a wireless charging system. [Jared] built it as a way to explore the concepts behind transferring power inductively. Alternating current on one of the white coils induces current on the other. This is then rectified, and regulated for use as a 5V charger. In this case it powers his iPod, but any USB device should work with the setup.

The transmitter uses the power supply from an old laptop as a source. Some filtering and a couple of MOSFETS are responsible for generating the AC current on the transmitting coil. The receiving coil feeds the bridge rectifier. In the writeup that voltage is fed to a 7805 regulator to provide a stable 5V output. However, in the video demo after the break [Jared] shows off the boost converter that he uses on his improved circuit. This way if the voltage drops due to poor alignment of the coils it will still be able to provide a steady output.

We’ve seen the same coil concept used to add wireless charging to cellphones too.

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ATtiny Hacks: Look Ma, No Batteries!

September 14, 2011 by Mike Szczys 30 Comments

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[Gadre] built his own ATtiny project without using any batteries. It’s an electronic Dice (or die if you’re being critical) which uses induction to charge a storage capacitor to act as the power source. The voltage generator is made from a tube of Perspex which houses a set of rare-earth magnets. At the enter of the tube [Gadre] machined a channel wich accepts about 1500 windings of 30 AWG magnet wire. When someone shakes the tube back and forth the magnet passes the wire, inducing a current. The product is stored in a 4700 uF capacitor, which feeds a boost converter to power the rest of the circuit.

The ATtiny13V that controls the circuit is running its internal RC oscillator at 128 kHz, the lowest setting possible in order to minimize power consumption. After a good shake the user can press a button to roll the die, which is then displayed for several seconds on a group of seven LEDs. See for yourself in the video after the break.

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