I need someone to explain this to me.

A Simple LED Flashlight Composed of a Relay and a Magnet

In our tips line we sometimes receive hacks that are amazing just because of their ingenuity. This relay-powered flashlight is definitely one of them. It has been named RattleGen by its creator [Berto], who apparently often makes simple hacks used in his everyday life (have a look at his YouTube channel).

To understand this hack, you first need to know (in case you didn’t already) that a magnet moving near a conductor (here a coil) induces a voltage at its terminals. This is called electromagnetic induction. In the picture you see above, you may distinguish a disassembled relay with a magnet located on the lever’s end. As a ferromagnetic metal is already placed inside the coil, the lever is by default ‘stuck’ in this position. By continuously pressing the latter on its other end, important voltage spikes are created at the coils terminals. [Berto] therefore used a bridge rectifier to transform the AC into DC, and a 1000uF capacitor to smooth the power sent to his super bright LED. A video of the system in action is embedded after the break.

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More Lights for your Presents

presLights

Lights on the tree? Check. Presents under the tree? Check. Lights in the presents? Why not! If your gifts don’t look festive enough and you have a spare inductive charging system lying around the house—though, you could always build your own from scratch—you can brighten things up by installing a few LEDs in the packaging.

The Instructable takes advantage of those new-fangled LED Christmas lights, one strand of which typically draws under 1A and requires around 5V, putting it in the ballpark for popular induction systems used to charge cell phones such as the Powermat. In this particular example, the strand ran off 3 AA batteries, or 4.5V, which meant stepping down the voltage either with a power regulator or, more conveniently, a simple diode in series.

Some additional modifications to the packaging tidy up the installation, including carving out some of the cardboard to recess the receiver and securing everything with hot glue before wrapping it all in paper. You can see a quick demonstration video below.

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Rattle generator is a new type of dynamo for a bicycle

rattle-generator-bicycle-spokes

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

inductive-charger-inside-furniture

[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

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

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

inductive-charge-led-lights

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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