The simplest and least expensive DC motors are "permanent magnet" motors.
This is the smallest D.C. permanent magnet motor in my parts box.
It has a tiny eccentric weight attached to the shaft.
This assembly is used in cell phones and pagers to implement the "vibrate" alert function.
This page from the
catalog (#103, Winter 2003) shows some DC motors.
Here's a D.C. gearmotor from my junk box.
This page from the
catalog (#103, Winter 2003) shows some DC gearmotors.
This indicates how much voltage (and what kind, AC or DC) must be applied to activate the motor. Watch out for current, which generally goes up as you give the motor a heavier load to move.
Make sure that the motor matches the power you feed into it! If you feed high voltage into a low-voltage motor, the motor will burn out. Sometimes you can operate a motor on a lower voltage than is specified.
Most DC motors tend to spin in one direction. Permanent magnet DC motors will usually spin in reverse when the power input is reversed.
Find out how fast the motor must spin for your project to work.
Find out how strong the motor must twist for your project to work. If you can't find exactly what you want, you can use a motor that develops more torque than you need.
Note that a DC Gearmotor trades speed for torque.
Some motors can operate 24 hours a day - "continuous duty" or "continuous operation". Other motors may develop amazing torque, but will burn out if you don't turn them off and let them cool down.
[You may be interested to know that, in the early years of the automobile, you had to use a big crank to start the engine spinning. A lot of people wanted to use an electric motor to crank the engine, but calculations showed that such a starter motor would have to be impossibly large. Then somebody figured out that the starter motor only had to run for a few seconds, and electric starters became practical.]
Not all of the power fed into a motor comes out as spin. Some quantity, often a lot, is wasted as heat. That heat has to escape, or the motor cooks itself.
This is why some motors have a limited duty cycle, some have built-in fans, and others specify the air flow around the motor necessary to keep it cool.
Look in stores that cater to electronic experimenters, such as:
Thank you for visiting. Your comments are welcome.
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