Wireless iPod charger built from scratch

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.

[Read more...]

ATtiny Hacks: Look Ma, no batteries!

ATtiny Hacks Theme Banner

[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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Hackaday Links: April 16, 2011

Induction cook top provides power too

We’re familiar with induction cook tops but we never thought to power a microcontroller with one. [Thanks Hadez]

Ping-Pong Uranium

We’ve been big fans of the chain reaction demonstration using ping-pong balls and mouse traps ever since we saw [Mr. Wizard] do it back in the day. If you don’t know what we’re talking about, check out this demonstration that is analogous of a fission reaction. [Thanks nateL]

Phone tripod enclosure

If you’re interested in using your smart phone for some photography, [Mike] has a nice wood and elastic mount for an iPhone which you might try yourself.

Bicycle snow tires

Admittedly we’re a bit late on this one. But keep it in mind for next year: you can use some zip ties for added traction on your bike when it snows. [Thanks Rob]

Now you can BE mario

A little Kinect script lets this gentleman play Super Mario Bros. with his body. Now you can have all the fun that goes along with being a pixellated character stuck in a two-dimensional environment (plus, there are shrooms). [Thanks Das_Coach via Slashdot]

Simple fluidyne engine

[Mirslav] built this fuidyne engine himself. This is a single piston model but you won’t find any precision milled cylinders here. That’s because fluidyne engines use columns of water as the pistons. In the rig shown above you can see one metal pipe which serves as the cold side of the loop. There’s another hot pipe underneath the insulation that completes the circuit. When that pipe is heated it causes the air inside the loop to expand, forcing the liquid on the open side of the plastic tubing (to the left) to rise. Once that air escapes to the other side of the circuit the water piston in the open tube falls back again. This results in continuous oscillation that can be used to drive a pump using a pair of check valves.

We’ve embedded a couple of videos after the break. You’ll see the system tested by heating one pipe with a hot air gun. But the example seen above uses an induction coil to bring the heat.

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Wireless electricity enables next generation of annoying packaging

Yep, these cereal boxes light up. They’re using a new branded-technology called eCoupling that provides electricity via induction, which means the shelves have a coil with AC power running through it. The “printed coils” on the boxes allow inventory control and data exchange presumably thanks to a low-power microcontroller. But in the video after the break you can see that the printed lighting on the boxes lets them flash parts of the box art as a way to attract customers’ attention. We’d bet that they’re using electroluminescent materials but we weren’t able to get find specifics on how this is done. We just hope advertisers don’t start rolling noise-makers into their packaging.

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Rodent-based power generation

Your hamster lives to good life, with food delivery and a maid service that cleans up after him. [DanF] helped to brighten up this hamster’s life even more by improving its exercise equipment and giving it a small night-light as well. This project adds a low RPM alternator to the hamster wheel.

The first part of the process was to reduce energy lost to friction by fitting the wheel with a bearing. From there a ring of permanent magnets was added which will pass by a stationary coil and induce a current. It works, but unfortunately there’s not enough power generated to charge a battery. That means the light is only on when the hamster is running. But maybe you can figure out a way to use a super-capacitor like we saw in that exercise bike hack.

One nice finishing touch to the setup is a bicycle computer to track how much time was sent on the wheel, and the distance traveled.

[Thanks Dizzy]

Spinning POV clock done oh-so-right

[Kizo] built an extraordinary persistence of vision clock. The design uses a PC cooling fan to spin the propeller-like PCB. As it goes around, a hall effect sensor synchronizes the illumination of the LEDs to draw the display. Power for the rotating electronics is transferred wirelessly via a transformer on the base and coil on the spinning board. The final version uses an ATmega324 microcontroller running at 20 MHz and has an IR receiver for changing the settings. The 3000 lines of code bring a lot of bells and whistles, including a menu system with a huge amount of settings from tweaking the clock display, to font selection for scrolling messages. Take a look at the demo after the break. The double-sided board looks like it’s pretty difficult to etch at home, but as you can see from the forum post (translated), [Kizo] did a great job on this build from start to finish. [Read more...]