Magnetic Powered Skateboard Figure--Santa's Shop 2016


Introduction: Magnetic Powered Skateboard Figure--Santa's Shop 2016

About: I am an author and a maker. My current project is Santa's Shop. I'm working on a science fiction type book--more later. @EngineerRigsby

This magnet powered car (skateboard figure) is one of many moving devices to be found in Christmas Display 2016. This figure will be joined by elves, Santa, and unusual toys to perform an electromechanical show.

The small wheeled car has a bar magnet glued on top. This magnet is pulled along the track by sequentially activated electromagnets.

Step 1:

Required parts include:

12 electromagnets

12 2n3904 transistors

12 1n4007 diodes

12 100 ohm resistors

Tiny solar car

12 volt dc, 500 milliamp power supply

9 volt dc power supply

Arduino Uno

Tiny skating figure

Bar magnet (one inch by 1/4 inch)

Step 2:

Remove the solar cell and motor from the tiny car. Glue the bar magnet lengthwise along the top of the car. Glue the skateboarding figure atop the magnet.

Step 3:

Apply 12 volts to each electromagnet. If the car is above the magnet, it will be pulled or pushed. When pulled, note which lead is attached to "plus" from the dc power supply. Mark this lead--it will be attached to positive in the operational configuration.

Step 4:

Using a 3d printer or print service, print three magnet holders and glue them together.

Step 5:

Lengthen the leads of the electromagnets, taking care to tape or heat shrink any connections so that they are not exposed or in a position to short against one another. Use the printed "wire pushers" to hold the wires in the wire tray.

Step 6:

Tape the track to the magnetic base and test the system using the Arduino sketch provided in step number one.

Step 7:

Glue (or melt with a soldering iron) the track to the magnet base.

The figure will "jerk" from position to position. Without feedback, it's difficult to smooth the motion. If the magnets are set in the pushing (repel) direction, the distance between magnets can be increased to 3 or 4 inches--but issues arise. If the car is directly above a magnet when it "repels," the car will flip or leave the track. If the car is stopped between magnets, the force from the nearest magnet will not restart it.

So, the next step in the evolution of this system will require feedback so that the magnets can be "fired" at the right time.



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    4 Discussions

    Nice. Have you tried to stepwise increase the speed between pulses so it acts like a rail cannon? Or so it looks like a more constant movement?

    3 replies

    It's surprisingly tricky. For example, if it's on magnet one and I fire magnet two, the car moves very rapidly to magnet number two--then slightly overshoots, then undershoots, then overshoots--until it settles (about 400 milliseconds). If (before it settles) magnet two is turned off and three turned on then it will either quickly jump to magnet three (if caught in overshoot position) or do nothing (in undershoot position magnet three's force can't reach it and magnet two--now turned off--won't pull it into three's range).

    I played with the timing and tried to get smooth (and rapid) motion; which sometimes I could. Often, the electromagnets would just lose the car and it would sit until they cycled beneath it again. I'm speculating (no proof here) that the friction of the tires (whether they are free or touching the side rails) causes the speed of the car to vary slightly.

    I tried with no side rails, but the thing quickly manages to turn a bit and not align with any field.

    I think "pushing" is the way to go since the car will move about four inches very quickly (if it's in the correct starting position). I've ordered more parts and hope to try something more like a maglev train (floating, pushing, feedback). Check out Tomy's toy maglev train

    This toy train is only sold in Japan and costs $400. to $700. to acquire in the U.S. Also--to cut costs--they put the electromagnets in the train rather than the track, so it's battery operated and has to be charged every 20 minutes or so.

    Interesting! I think, if you use H-bridges to reverse magnetism you can create a push-pull. But then I guess the induction can become a problem as not to kill the H-bridge. Creating a maglev seems to be more tricky than one would think on the first hand.

    I had not considered the H-bridge, but you're right that (if coil inductance and timing can be worked out) a push-pull operation would provide the most movement per electromagnet.

    It's an interesting project to examine!