Magnet Mobil

Summary

The Magnet Mobil is a 3D-printable recreation of a simple electromagnetic vehicle originally supplied with the German YPS children’s magazine in 1980. Watch the completed Magnet Mobil driving: YouTube video Its mechanism remains completely visible. Permanent magnets around the flywheel operate a reed switch, which briefly connects two AA batteries to a hand-wound electromagnet. The resulting magnetic pulses keep the flywheel turning, while a rubber-band belt transfers its rotation to one of the road wheels. The Magnet Mobil Mk II has been successfully built and driven. The demonstrated configuration uses: - An approximately 460-turn, 4 Ω electromagnet - Approximately 20 m of 0.3 mm enamelled copper wire - An 8 mm × 30 mm ferromagnetic core - Two AA batteries in series, providing approximately 3 V - 25 mm road wheels - A rubber-band belt with an unstretched circumference of approximately 15 cm - A reed switch for magnetic timing - A 1N4148 flyback diode - A simple custom PCB

The standard flywheel configuration uses six neodymium magnets. An optional twelve-magnet configuration is also included. Build instructions

The complete illustrated Magnet Mobil build guide contains: - The complete parts list - Recommended print settings - The circuit diagram - Electromagnet winding instructions - Step-by-step assembly photographs - Reed-switch positioning and timing instructions - Mechanical and electrical testing procedures - Troubleshooting advice

Printing

The OpenSCAD model is parametric, allowing dimensions and clearances to be adjusted for different printers and components. An open STEM project

The Magnet Mobil brings together electromagnetism, reed switches, inductance, flywheel inertia, friction, belt drives, electrical circuits, measurement, CAD, 3D printing, and iterative engineering. The source files are shared in an open-source spirit. Makers are encouraged to modify the design, experiment with the magnetic and mechanical configuration, and adapt it to locally available components. The circuit can also be assembled without the custom PCB. The prototype demonstrably drives, although long-term coil temperature, reed-switch durability, flyback-diode suitability, and overall runtime still require further measurement.