Mendocino motor
A solar-powered, magnetically levitated motor for demonstrations.
The Mendocino motor is an electric motor that runs on solar power and uses magnetic levitation. Because it produces very little power, it is mainly used as a demonstration piece, though it remains a favorite building project for electronics hobbyists.
The motor’s rotor is a horizontal shaft fitted with a barrel-shaped array of solar panels and electromagnetic coils—usually four to eight sets. This rotor sits in frictionless radial bearings above a central magnet fixed to the base plate. The remaining direction of movement (the axial, or thrust, direction) is not levitated; instead, a steel ball provides a low-friction point of contact.
In the original design, the motor is light-commutated. Two opposite solar panels are wired so that each panel’s positive connects to the other’s negative, and vice versa. A coil is switched between these bridges. The panel in sunlight generates more electricity than the one in shadow, so the lit panel controls the current flow. The coil and the base magnet produce a Lorentz force, which rotates the rotor and brings the next panel into the light, keeping the motion going. If the rotor is well balanced, it can start itself with enough light—even a candle can get it moving.
A later modification uses one coil powered by one opposite solar panel. This is easier to build but works less well than the light-commutated version, and many such motors need a push to start.
The concept of a light-commutated motor—where solar cells directly power individual motor coils—first appeared in a 1962 experiment kit about solar energy, created by Daryl Chapin. The kit was distributed by Bell Labs, where Chapin, along with Calvin Fuller and Gerald Pearson, had invented the modern solar cell eight years earlier. Chapin’s motor used a vertical glass cylinder balanced on a needle point as a low-friction bearing.
In 1994, inventor Larry Spring added magnetic suspension to the rotor, creating “Larry Spring’s Magnetic Levitation Mendocino Brushless Solar Motor”—now commonly called the Mendocino motor, with a horizontal rotor. The name comes from the location of his workshop on the Mendocino coast of California.
- Rotor shaft solar panels
- typically four to eight
- Rotor orientation
- horizontally mounted
- Bearing type
- frictionless radial bearings over a central magnet
- Axial support
- steel ball point of contact
- Original inventor of light commutated mo
- Daryl Chapin
- Year of original experiment kit
- 1962
- Inventor of magnetic suspension
- Larry Spring
- Year of magnetic suspension addition
- 1994
Lore & Background
The idea of a light-commutated motor, where solar cells power the individual coils of a motor, was first described by Daryl Chapin in an experiment kit from 1962 about solar energy. The kit was distributed by Bell Labs, where Chapin together with his colleagues Calvin Fuller and Gerald Pearson had invented the modern solar cell eight years earlier, in 1954. Chapin's version of the motor uses a vertical glass cylinder on a needle point as a low-friction bearing.
A magnetic suspension of the rotor was added in 1994 by inventor Larry Spring to create 'Larry Spring's Magnetic Levitation Mendocino Brushless Solar Motor' - more commonly called 'Mendocino Motor' with a horizontal rotor. The name comes from the location of his workshop on the Mendocino coast of California.
The motor consists of a rotor shaft with an array of (typically four to eight) solar panels and electromagnetic coils arranged in a barrel shape around the centre of the shaft; this rotor is horizontally mounted in frictionless radial bearings over a central magnet on the base plate of the motor. The final 6th degree of freedom, the axial or thrust direction, is not levitated, but rather supported by a steel ball point of contact (low friction). An original Mendocino Motor is a light commutated motor. Two opposite solar panels are connected plus to opposite minus and minus to opposite plus. A coil is switched between these bridges. The solar panel in the sun/light produces more electricity than the solar panel in the shadow. So the solar panel in the sun dominates the flow of electricity. The coil and the base magnet create Lorentz force and so a movement that leads the next solar panel into the sun/light, thus maintaining the rotation. If the rotor is well balanced the rotor will start itself with enough light. Even a candle light could start a very well balanced rotor. In a modification, new constructors used one coil each supported by one opposite solar panel. It's easier to produce but this design isn't as favorable as the light commutated version. Many of these motors need an initial impulse to move.
Reader's Guide
The Mendocino motor is notable primarily as a technical demonstration and a popular construction project for electronic enthusiasts, owing to its very low power output. Its significance lies in combining two earlier innovations: Daryl Chapin's 1962 light-commutated motor concept and Larry Spring's 1994 addition of magnetic levitation. The motor's design—using solar panels to commutate current through coils, creating Lorentz force against a base magnet—allows it to self-start under sufficient light if well balanced, though modified versions often require an initial impulse. Its legacy is as an educational and hobbyist device that illustrates principles of solar power, magnetic levitation, and electromagnetic rotation, rather than as a practical power source.
Did You Know?
- The motor's name comes from the location of Larry Spring's workshop on the Mendocino coast of California.
- An original Mendocino Motor is a light commutated motor, where solar panels in sunlight dominate the flow of electricity.
- The axial direction is supported by a steel ball point of contact, not levitated.
Frequently Asked Questions
What is a Mendocino motor and what is it actually used for?
The Mendocino motor is a small, solar-powered electric motor that uses magnetic levitation to reduce friction. Because its output is extremely low, it is not a practical power source; instead it serves as a demonstration piece and a beloved hands-on build project for electronics hobbyists.
How does the Mendocino motor stay suspended without touching the base?
The rotor rests in frictionless radial bearings above a central magnet fixed to the base plate, which handles the radial levitation. The remaining axial (thrust) direction is not levitated at all—it is simply supported by a single steel ball contact point.
What does the rotor of a Mendocino motor look like?
It is a horizontally mounted shaft wrapped in a barrel-shaped array of solar panels paired with electromagnetic coils, typically arranged in four to eight sets. This whole assembly spins freely above the base magnet thanks to the radial bearing arrangement.
Who originally created the light-commutated motor concept behind the Mendocino design?
The foundational light-commutated motor experiment is credited to Daryl Chapin, who first demonstrated the concept in a kit released in 1962. That early prototype is the direct ancestor of the Mendocino motor kits hobbyists still assemble today.
Why do electronics hobbyists keep building Mendocino motors even though they produce almost no usable power?
The appeal lies in seeing solar energy, electromagnetism, and frictionless levitation all working together in one tiny, self-contained device. It is a compact, satisfying build that makes abstract physics tangible, which is exactly why it remains a favorite demonstration project despite its negligible output.
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