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Topic: Salvaged from Scanner: What kind of motor is this? (Read 1 time) previous topic - next topic


Hi Everyone,

Just took apart a Canon LIDE scanner and am trying to identify the motor. Being a scanner, one assumes that it is a stepper, but beyond that, how can one tell if it is a unipolar or bipolar motor? I searched online for image references to differentiate but couldnt come up with anything.

Beyond that, is it possible to control this with the arduino without an intermediate driver? Checked the libraries on the arduino site and they seem to indicate the need for a "H-Bridge" (bipolar) or a "Darlington" (unipolar) . Is there any work around for this, or why is it necessary?

And forgive this last simple question: alot of posts say it is best to have an external power supply for the motor, but also that too much power will fry it. What would one use to modulate the power being fed to it? I mean this in the simplest way: in my mind, external power supply means hooking it up to a 9v battery or simply plugging it into the wall (this sounds like a bad idea...)


Can you read any markings on the battery at all? Does it just have 3 connections, or a 4th that is not visible in this picture?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


It has 4 connections. Does that mean its a bipolar?


With four wires it has to be bipolar.

First step would be to find the continuity between the four wires. That should break it into two pairs (two coils).

If the resistance in each pair is 125 ohms or more (5V / 40ma max per pin = 125) then you can drive it directly from the Arduino's pins. If not you'd need to set up a basic transistor circuit so you can use more than 40ma or add a resistor to one of the lines of each of the coils.

The Stepper library would handle the rest for you. If the stepper doesn't turn properly then reverse the connections for one of the coils.


Hi, With a bipolar motor you need to be able to reverse the direction of current flow in each winding.

Some stepper and motor info here:  http://arduino-info.wikispaces.com/TUTORIALS
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info


I certainly wouldn't run it directly from the Arduino pins, its an inductive load.
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