Electric Train Demonstrator

If you ever want to pique a kid’s interest in technology, it is best to bring out something simple, yet cool. There was a time that showing a kid how a crystal radio could pull in a radio station from all the way across town fit the bill. Now, that’s a yawner as the kid probably carries a high-tech cell phone with a formidable radio already. Your latest FPGA project is probably too complicated to grasp, and your Arduino capacitance meter is–no offense–too boring to meet the cool factor criterion.

There’s an old school project usually called an “electromagnetic train” that works well (Ohio State has a good write up about it as a PDF file). You coil some bare copper wire around a tubular form to make a tunnel. Then a AAA battery with some magnets make the train. When you put the train in the tunnel, the magnetic forces propel the train through the tunnel. Well, either that or it shoots it out. If that happens, turn the train around and try again. There’s a few of these in Internet videos and you can see one of them (from [BeardedScienceGuy]) below.

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Homemade EDM Can Cut Through Difficult Materials Like Magnets With Ease

Many years ago [ScorchWorks] built an electrical-discharge machining tool (EDM) and recently decided to write about it. And there’s a video embedded after the break.

The build is based on the designs described in the book “Build an EDM” by Robert Langolois. An EDM works by creating lots of little electrical discharges between an electrode in the desired shape and a material underneath a dielectric solvent bath. This dissolves the material exactly where the operator would like it dissolved. It is one of the most precise and gentle machining operations possible.

His EDM is built mostly out of found parts. The power supply is a microwave oven transformer rewired with 18 gauge wire to drop the voltage to sixty volts instead of the oven’s original boost to 1.5kV.  The power resistor comes from a dryer element robbed from a unit sitting beside the road. The control board was etched using a hand traced schematic on the copper with a Sharpie.

The linear motion element are two square brass tubes, one sliding inside the other. A stepper motor slowly drives the electrode into the part. Coolant is pumped through the electrode which is held by a little 3D printed part.

The EDM works well, and he has a few example parts showing its ability to perform difficult cuts. Things such as a hole through a razor blade., a small hole through a very small piece of thick steel, and even a hole through a magnet.

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Real World Race Track is Real Hack

[Rulof] never ceases to impress us with what he comes up with and how he hacks it together. Seriously, how did he even know that the obscure umbrella part he used in this project existed, let alone thought of it when the time came to make a magnet mount? His hack this time is a real world, tabletop race track made for his little brother, and by his account, his brother is going crazy for it.

His race track is on a rotating table and consists of the following collection of parts: a motor, bicycle wheel, casters from a travel bag, rubber bands (where did he get such large ones?), toy car and steering wheel from his brother, skateboard wheels, the aforementioned umbrella part and hard drive magnets. In the video below we like how he paints the track surface by holding his paint brush fixed in place and letting the track rotate under it.

From the video you can see the race track has got [Rulof] hooked. Hopefully he lets his brother have ample turns too, but we’re not too sure. Some additions we can imagine would be robotics for the obstacles, lighting, sounds and a few simulated explosion effects (puffs of flour?).

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3D Carver Makes Magnetic Fields Visible

The history of science is full of examples when a 3D physical model led to a big discovery. But modelling something that’s actually invisible can be tough. Take magnetic fields – iron filings on a card will give you a 2D model, but a 3D visualization of the field would be much more revealing. For that job, this magnetic field following 3D carving machine is just the thing.

What started out as a rapid prototyping session with servos and hot glue ended up as quick and dirty 3D carving rig for [Frits Lyneborg]. The video shows his thought progression and details how he went from hot glue and sticks to LEGO Technics parts and eventually onto Makerbeam extrusions for the frame of his carver. A probe with a Hall effect sensor is coupled to a motor spinning a bit that cuts into a block of floral foam. A microcontroller keeps the Hall sensor a more or less fixed distance from a rare-earth magnet, resulting in a 3D model of the magnetic field in the foam, as well as a mess of foam nubbles. Despite a few artifacts due to in-flight adjustments of the rig, the field presents clearly in the block as two large lobes.

Carving foam isn’t the only way to visualize a magnetic field in three dimensions, of course. If you’d rather have a light show based on the local magnetic field, try this 3D compass build we covered a while back.

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Speaker Science Project

They probably won’t please the audiophiles, but [KJMagnetics] shows you that can create a pair of speakers with some magnets, some plastic cups, and a bit of magnet wire. Creating speakers out of junk isn’t a new idea, of course. However, there’s something pleasant about the build. Maybe it is the symmetry of the cups or the workbench look of the woodworking.

We couldn’t help but think that this would make a good science fair project or a classroom activity. Especially since there is a good write up on how speakers work and it would be easy to make simple changes to test different hypothesis about speakers. For example, what happens with more or less wire in the coils? What magnets work best? What does best even mean? Is it louder? Less distortion?

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[Amazing Science’s] Simple Electric Train

Making an electromagnet is as simple as wrapping some wire around a nail and taping the wire to both ends of a battery. When you’re done, you can pick up some paper clips – it demonstrates the concept well, but it could use some more oomph. [Amazing Science] has done just that, making an “electric train” (YouTube link). All that’s needed is some coiled copper wire, a battery and magnets thin enough to fit through the coils. The magnets snap onto both ends of the battery. Put the battery inside the coil and watch the fun! The electromagnetic force generated by the current moving through the coil pushes against the magnets attached to the battery, pushing the battery along the way.

[Amazing Science] plays with the setup a bit. Connect both ends of the coil together and the battery will travel in a loop until it’s drained. Add a small hill, or even another battery/magnet set to the mix, and watch them go! We may even make a version of this ourselves to take with us to family gatherings this holiday season – it’s simple, fun, and can teach the young ‘uns about science while we swig some egg nog.

[via Reddit]

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Beamboarder Lets You Skate at Night; Won’t Blind Oncoming Traffic


Whether you use your longboard as transportation or pleasure riding, night-time sessions can be harrowing if you’re screaming through poorly-lit places. The Beamboarder is a solution that is simple to build and easy to throw in a backpack whenever that giant ball of fire is above the horizon.

Boiled down it’s a high-power LED and a Lithium battery. How’s that for a hack? Actually it’s the “garbage” feel of it ([Lyon’s] words, not ours) that makes us smile. An old hard drive with as high of a capacity as possible was raided for parts. That sounded like a joke at first but the point is that early, large drives have bigger magnets inside. You need a really strong one because that’s all that will hold the LED to the front truck of our board. From there it’s a matter of attaching a CREE LED with thermal adhesive and wiring it up to the Lithium pack that has been covered in shrink tube to keep the elements out.

The headlight is under the board, which is courteous to oncoming traffic. Once you pull off this hack we’re sure you’ll want to go further so we suggest wheels with LED POV displays and there’s always the option of going full electric.