Connecting a stepper motor to an Arduino board

[Skigh]

Hello forum,

I came here to seek for your help on a circuit matter. I just recently started this hobby and i am kinda lost with my project. The project is a 2d plotter or cnc machine without a drill. Its a prototype to see what the posibilities are. I am doing this for a schoolproject and unconveniently enough the deadline is in 2 weeks.

So here is the problem, i have an arduino board and a 39d1126 steppermotor (4.1 ohm, 1.8 degrees turn) I Saw an example at a site called azega.com http://www.azega.com/controlling-a-stepper-motor-with-an-arduino/ , it was a pretty simple circuit but the actual problem is that i dont know how much power/current the stepper motor can take. Or in other words, i dont know which resistors i can use. So do you think i could use the same transistors as they use in the link or is it better to use something else?

Thanks so much in prospect!
Cheers,
Skigh

(Ps, any helpfull information on steppermotors is welcome too)

 

[wingnut]

I do not understand your commitment to complexity???

I have made a solar tracker with two photoresistors, 4 resistors, two comparators on one cheap chip, a dual H-bridge motor driver and a dc motor, and it cost little, worked great and was easy to understand.

I think there is something wrong with your decade-counter circuit. The decade counter (CD4017) is supposed to trigger in sequence switching on the stepper motor coils in sequence. As that circuit is drawn, all the output pins from the decade counter are connected, so there is no sequence - they are all on at the same time. Thus I cannot explain your circuit - sorry.

 

[Skigh]

I do not understand your commitment to complexity???

I have made a solar tracker with two photoresistors, 4 resistors, two comparators on one cheap chip, a dual H-bridge motor driver and a dc motor, and it cost little, worked great and was easy to understand.

I think there is something wrong with your decade-counter circuit. The decade counter (CD4017) is supposed to trigger in sequence switching on the stepper motor coils in sequence. As that circuit is drawn, all the output pins from the decade counter are connected, so there is no sequence - they are all on at the same time. Thus I cannot explain your circuit - sorry.

thanks for your reply,
But I think you misunderstood the problem .
The circuit shown in the link (http://www.azega.com/controlling-a-stepper-motor-with-an-arduino/) is almost perfect for me. The remaining problem is that i dont know which transistors to use. I couldnt find the data sheet for my 39d1126 steppermotor so i dont know which resistors, transistors and diodes i have to use in order to prevent the motor from overheating or anything like that.

This is the schedule:

 

[(*steve*)]

What voltage are you running the stepper motor at?

And what current does the stepper motor draw at that voltage?

Answer these two, then find a transistor (possibly a mosfet) which can comfortably switch that.

Add heatsinking if required.

 

[Skigh]

thats the problem, i dont know what voltage the motor can take. And due to the limited amount of time for this project i cant use another motor.
so what do you think would be a safe voltage/current to run this motor on?

 

[wingnut]

My apologies Skigh. I was replying to another thread on a solar tracker using a stepper motor - and by mistake posted here.

 

[(*steve*)]

I can't guess what voltage or current your stepper motor might operate at.

Does it have anything written on it?

How big is it?

How heavy?

Where did it come from?

 

[BobK]

A quick search shows these all over the net, it looks like a take-out from HP printers. But no one seems to have voltage / current specs.

Bob

 

[(*steve*)]

If we knew the model of printer we might be able to start to guess. (Because we could look up the power supply specs and guess what voltage was used. From there a measurement of the inductance and resistance of a winding would get us into the ballpark.)

 

[(*steve*)]

OK, so the resistance of the windings is 4.1 ohms. It may be that this stepper motor was designed to drive (and not hold) something. The "hold" current at 5V would exceed an amp, but while stepping (especially at speed) would likely be somewhat lower.

I would try a power supply of 5V and capable of 1.5A per winding that you'll have powered simultaneously (often the answer to this is 1)

 

[Skigh]

OK, so the resistance of the windings is 4.1 ohms. It may be that this stepper motor was designed to drive (and not hold) something. The "hold" current at 5V would exceed an amp, but while stepping (especially at speed) would likely be somewhat lower.

I would try a power supply of 5V and capable of 1.5A per winding that you'll have powered simultaneously (often the answer to this is 1)

thanks so much! i will just run some tests and check if the motor runs correctly. Speed is not very important and 5V is the max voltage for the arduino.
I ll post as soon as i get the results

 

[BobK]

thanks so much! i will just run some tests and check if the motor runs correctly. Speed is not very important and 5V is the max voltage for the arduino.
I ll post as soon as i get the results

I hope you are not expecting to drive the motor directly from Arduino outputs.

Bob

 

[(*steve*)]

And I'd suggest you'd want a separate 5V power supply t power the motor to the one powering the arduino (or more likely a well decoupled one.