Marinov Motor

By: Spatula Tzar

This is a large demonstration quality device, meant to teach others about this pecular mechanism. As much care was taken in the artistic design as the technical.

Electrically, the motor is trivial. The secondary winding of a microwave oven transformer was removed, and replaced with a few turns of four gauge (21.2 mm²) copper wire. This high current source is simply connected directly to the bearing housings. The transformer core is connected to mains earth for safety.

Please excuse the poor crimping of the wire connectors. A proper gas tight compression crimping tool was not available.

The bearings used are ordinary 3/4" steel ball bearings. The metal bearing shields were removed, and the grease was replaced with lightweight oil to reduce rolling resistance. This configuration works well, but requires more maintenance to keep the bearings clean.

The bearings are connected to the main drive shaft: a lovely 3/4" cylinder of 316L stainless steel. Stainless steel isn't the best electrical conductor, but the large cross sectional area more than makes up for this.

Stainless steel fasteners attach the transformer and bearings to the wooden base, through countersunk holes. Normally the bolts would be secured with nylon insert locknuts, but temperature concerns forced the use of lockwashers instead. The bearings become so hot during operation, it can only be run a few seconds at a time.

I'm particularly fond of this base. It's made from a branch of burr oak (Quercus macrocarpa) which fell in a storm. It was quartersawn, sanded, and finished with acrylic. No stain was needed, and the bark remained intact.

Here is a video of the device in operation. The ammeter peaks at 343.2 A. With a voltage drop of about 2.3 V measured at the bearing housing bolts, this gives a total of about 800 Watts dissipated by the motor.