The motor that made AC move.

Tesla's 1888 electromagnetic motor patent turns alternating currents into a magnetic field that appears to rotate around an iron ring. A movable magnetic element follows that field — producing continuous rotation without a mechanical commutator.

A ring of laminated iron.

The patent specifies an annulus built from thin insulated iron rings or plates. That construction limits unwanted induced currents while allowing the magnetic condition of the ring to change rapidly as the two AC phases rise and fall.

Two pairs. Ninety degrees apart.

Four insulated coils sit symmetrically around the annulus. Diametrically opposite coils act as pairs. Feed the two pairs with alternating currents displaced in phase and the magnetic poles do not merely reverse — the resultant field progresses around the ring.

The field leads. The rotor follows.

Inside the ring, Tesla describes a freely turning magnetic element. It continuously seeks the point of greatest magnetic attraction. Because that point keeps moving around the stator, the rotor is pulled into rotation.

Watch the magnetic field rotate.

This is the essential idea: independent alternating currents create a progressive shift of magnetic poles. The glowing field visualization is interpretive, but its motion represents the operating principle Tesla described in the 1888 patent.

Take it apart like a watch.

Every major assembly in this exhibit is independent 3D geometry. Use the component controls to isolate the annulus, coils, rotor, shaft and terminals, or pull the whole machine apart and rotate it from any angle.