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3v motor, 12v power supply Answered

I have a 3v DC motor, a 12v power supply, and various resistors. Can I use resistors in series with the motor to keep it from burning up?

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kelseymh (author)2010-03-06

You can in principle, but you're likely to burn up the resistors instead.  What kind of current does the motor draw?  You need use V=IR to figure out what resistance R you need to get the 9V drop for your motor.  Then you need to compute P=I2R to know how much power (watts) those resistors are going to have to dissipate.  If you're using typical 1/4W resistors, then you'd better have P < 0.25.

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