Finding the needle in a haystack

July 24, 2003
Dc motors from Maxon Precision Motors, Burlingame, Calif. (, use moving coils.

Moving coils upgrade dc motors

Red = Motor component
Green = Gearhead component
Blue = Encoder component

DC motors from Maxon Precision Motors, Burlingame, CA ( uses a moving coil design for their motors. And there are several reasons. The moving coil design reduces inductance, extends brush life and limits electrical noise to extremely low levels. The moving coil design gives the motors low inertia for fast acceleration. This design boosts efficiency, meaning current consumption is low and battery life extended (if the motor is battery powered). Designers use ironless rotors in the brush motors which contributes to their smooth operation and lack of cogging. The motors are not subject to magnetic saturation during operation so speed and torque constants are linear and control is simple and accurate.

Maxon can alter the number of windings and wire diameter to meet user torque and speed needs, and has a variety of brush materials available. Graphite brushes, for example, are often used in larger motor with high current loads. Precious-metal brushes are usually specified in smaller motors. And the company also offers a variety of magnets, ranging from cost-effective ferrite magnets to state-of-the-art rare earth magnets. Maxon also makes brushless versions and the their entire family of motors range in size from 6 to 90 mm diameter and in power from .03 to 500 watts.

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