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Max voltage for a motor


 I have some DC motors disassembled from a printer (HP Business Inkjet 1000) and need to know their working/maximum voltage. Searching the motor's model name in google revealed nothing.

The printer works on 32 volts (!), but I doubt all that juice arrives to the motors.
In its current condition, there's no chance to test the voltage while printer is running.

Besides a trial and error approach that might fry the motors - How can I find the correct voltage for each motor?

 I did find that the largest motor creates 10 times the voltage compared to a toy motor when rotating them with the same RPM (using a drill) - Can this be a clue of some sort?

 Image of the motors can be found here: http://dl.dropbox.com/u/2480317/Motors.jpg







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Check out the motor in the top of the image. It has an encoder wheel. Do try to salvage the detector that was mounted near that transparent disk. It may come in handy some day when you want to know how fast the motor is running.

Dont worry, I already have plans for this motor+encoder :)

I'm just wondering if the detector will run on 9-12 volts like the motor probably does. Usually these things work with 5v.

There are no markings on the encoder/detector that can give a clue.



The HP Inkjet 1000 series printers use that 32V line for the MEMS thermal printhead array, the motors normally use the 12V line.
Motors of that size are normally specced to operate from 9-12V, they've got thicker wire which can handle more power. My suggestion would be to run one of the at 9V for a minute or two, and check how hot the motor gets. If it's not too hot after a solid run, then you can safetly bump the voltage up to 12V, but I wouldn't go any higher than that.

The voltage generated by the motor at a set rotational speed tells you about how many windings there are, and what the internal field strength is, but unfortunately they don't give you much of a clue as to how much power the windings can handle before burning out. The much higher voltage output is a sign that the motor probably has good strong magnets, and a nice winding configuration at least.

Makes sense. I'll try that.