Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Trouble Identifying parts

  1. Oct 6, 2009 #1
    I have multiple stepper motors i pulled out a printer and I can't seem to find any datasheets on anything. For example one of the motors is made by OKI and it has numbers 3Y25AE1 and QH4-4490. I have looked all over the internet and I can't find anything. If anyone knows a good idea to try it is greatly appreciated. Thanks
  2. jcsd
  3. Oct 7, 2009 #2
    If needed, you can easily map the windings using a multimeter or a simple DC continuity tester.
  4. Oct 7, 2009 #3


    User Avatar
    Science Advisor

    If you have a 5 volt supply able to supply an amp or two, you can watch the shaft of the motor while you put the 5 volts across the different wires. If nothing happens, reverse the polarity.

    It is worth marking the motor or attaching a sticky label to the shaft as the movement can be very quick and you might miss it.

    Something else you can do is to do a search for the printer you took the motors out of and try to get a circuit diagram. This will tell you quite a lot about the stepper motors.

    Most of these motors have two separate windings and 4 wires. this means they are bipolar motors and need their polarity reversed during rotation.

    We had a similar question a few months ago and I found the following web site then which seems to cover stepper motor theory quite well.
  5. Oct 7, 2009 #4
    Thanks for the input. I don't know much about stepper motors at all as I have never used them, but I am willing to learn. I should have included that on the sticker it also says DC24.2V 3.8(ohm) and 3.75Deg/Step.

    Is that voltage the maximum voltage that can be applied to the motor? I'm not looking for torque at all since a mirror will be mounted on the motor so 5V-12V with the same speed output would be sufficient. I'm trying to build a laser scanner with it. thanks again.
  6. Oct 7, 2009 #5
    To make this work, you have to identify the windings, then build a driver to control in sequence which coils to activate:
  7. Oct 7, 2009 #6


    User Avatar
    Science Advisor

    Unless you especially like that stepper motor, it may not be the best choice.

    3.75 degrees per step is pretty rough as most stepper motors seem to be 1.8 degrees per step.
    3.75 means 96 steps per rotation while 1.8 means 200 steps per rotation.

    Also, that power requirement is pretty inconvenient. 24.2 volts across 3.8 ohms is 6.3 amps.
    It might work on less, but if you have to be switching and reversing 24 volts at 6 amps, that will be a serious controller.

    You would need to drive a controller chip like a L297 with a microprocessor and this L297 would drive a power amplifier like a ULN2075 which would then drive the stepper motor.

    On the printer you pulled apart, there may already be similar ICs to these, and they could be worth salvaging as these chips are not cheap.
  8. Oct 7, 2009 #7
    Ouch, I already threw away the chips. I'm really just experimenting right now so if the degree/step is too high I can always buy a better one or develop another way like galvos. I think I will just experiment with lower voltages and a mcu and see what I can do. Thanks for the input.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook