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### Topic: Determining motor voltage (Read 414 times)previous topic - next topic

#### rwiens

##### Oct 22, 2012, 02:59 am
I have taken apart a couple of old printers for the motors, but can't find any information that leads me to the voltage and current specs.  I can find replacements for one of them in a bunch of places on the internet, but none of the site show any specs.

The only clues I have are the power suppies from the printers.  One produces 36V and the other 24V (both also have a 5V logic supply).  Is it safe to assume that these are the motor voltages?  They are both straight DC brushed motors (or at least I think so since they only have 2 wires).

Presumably I can measure the impedance of the windings to get an idea of what current will be drawn for a given voltage, but short of cranking up the voltage until something melts, is there a way to determine the ideal and/or maximum voltage?  Is there a general rule of thumb about what kind of operating voltage range is used for printers?

#### Osgeld

#1
##### Oct 22, 2012, 03:09 am
measure it before you take it apart?

#### MarkT

#2
##### Oct 22, 2012, 04:05 pm
It is likely to be the motor voltage - 24V or 36V is far too high for logic and is likely only to be needed for electromechanical parts (motors, solenoids).

You can measure the motor winding resistance - then you can calculate the stall currents.  Actually running current should be a lot less.

The overall size of the motor gives a clue as to its power handling too, but the most useful thing is any part numbers present on it that might be catalogued on the web, or any specs like rpm, current, power etc.

It you are worried it might be a lower voltage motor try running it at about 6V - if it runs obviously slowly you can be fairly sure its more like 24V (allow for any built-in gearing).
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#### rwiens

#3
##### Oct 22, 2012, 05:05 pm
Both motors were being used to drive the print head, so I'm guessing they needed some 'oomph' to do that (as an aside, I am surprised that they didn't need steppers for this to get the necessary precision).

I will try the 'start small' approach and see what happens.

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