# How do I know whether a circuit (originally for 5 wire) will work for four wire stepper motor?

There is a very old and popular instructable 3 axis stepper motor driver, http://www.instructables.com/id/Easy-to-build-CNC-Mill-Stepper-Motor-and-Driver-ci/

As clear from the image , it's a six wire motor connected to the circuit. According to me the same circuit should also work for the four wire Bipolar stepper , as I can see that the center-taped-wires are directly connected to the bulb ( bulb is there in circuit only for testing purposes ).

So how do I actually determine whether or not this circuit work . What could be some modifications I can do with this circuit to make it run with my four wire steppers ?

My steppper motor mode no. is : 17PM-J311-P1ST ASTROSYN (sorry I failed to get an image of my motor)

Your circuit is for a standard four-coil (five or six wires) unipolar stepper motor. Such a circuit can cause current in one direction through four coils, thus making the four steps. Such a circuit has four open-collector/open-drain outputs.

A standard two-coil (four wires) stepper requires a driver circuit that can cause current through the two coils in two dircetions, thus again making four steps. Your circuit can't do that, you need a circuit with two full H-bridges (four push-pull output stages).

• So what additions/modifications I need to do to make it compatible with Bipolar 4 wire stepper ? It should be compatible with software also , otherwise no use .I was trying to implement a 3 or 4 axis stepper for 3D printer , I had thought and researched a lot in this regard but no clue, no luck . I have no idea how to g for it , have a look at this question please electronics.stackexchange.com/questions/94723/… Dec 27, 2013 at 12:10
• You will need a totally different circuit. It will probably be easier to find a unipolar stepper! Dec 27, 2013 at 12:12
• Well what about this circuit eeweb.com/blog/extreme_circuits/stepper-motor-controller . This is for bipolar steppers and it's pretty much same as the circuit mentioned in the question . Dec 28, 2013 at 5:18
• That is indeed for a bipolar stepper, and I would call that an entirely different circuit. I see no diodes at the outputs, which makes me nervous. I don't think the audio chips used in the circuit are designed to withstand the back-EMF pulses from the stepper. Dec 28, 2013 at 8:11
• Oh , I would add them , however I feel the circuits are similar. Isn't it ? Dec 28, 2013 at 8:17

According to me the same circuit should also work for the four wire Bipolar stepper

No it will not work.

the center-taped-wires are directly connected to the bulb ( bulb is there in circuit only for testing purposes ).

No that is not its purpose, it is connected to limit the current, it can be replaced with a resistors. According to the author I found it's good to have some voltage drop there as kind of a ballast for the motor windings

In a Uni-polar motor the current direction doesn't change so you just apply the positive supply to the center pin of the coils and then apply the ground to the other side of the coils to step the motor.

On the other hand a Bi-polar motor has two windings and you need to use a circuit that constantly inverts the polarity of the supply to the coils.

This is done with an H-bridge that operated as four switches. In practice these switches are either mosfets or transistors

Refer to the below articles for stepper motor driving:
http://www.8051projects.net/stepper-motor-interfacing/introduction.php
http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/

• So what additions/modifications I need to do to make it compatible with Bipolar 4 wire stepper ? It should be compatible with software also , otherwise no use .I was trying to implement a 3 or 4 axis stepper for 3D printer , I had thought and researched a lot in this regard but no clue, no luck . I have no idea how to g for it , have a look at this question please electronics.stackexchange.com/questions/94723/… Dec 27, 2013 at 12:10
• @user34427 It is not just a matter of circuit modification and you need to change the logic too. One of the popular motor drivers is L293 but note that it is transistor based so expect about 4-5v voltage drop from supply to motor plus heat on the driver. Dec 27, 2013 at 12:18
• Gotcha! I'll have to use the driver (l293D) + the controller (like a UNO) , but in that case I'm falling short of PWM pins, I need to drive 4 motors and for each motor 3 PWMs are required , I can't afford to buy a due or a MEGA. Dec 27, 2013 at 12:25
• @user34427 then you can use a controller like A4988. You can buy complete boards for a few dollars in ebay, Each one can fully control one motor Dec 27, 2013 at 13:15
• Well what about this circuit eeweb.com/blog/extreme_circuits/stepper-motor-controller . This is for bipolar steppers and it's pretty much same as the circuit mentioned in the question . Dec 28, 2013 at 5:18