Driver for Mercury Motor SM-428YG011

I'd like to know which stepper motor driver would be suitable for the Mercury Motor SM-428YG011-25 1.8º 12v Bipolar motor.

I've already bought two combinations of stepper and driver that don't work, for the Mercury Motor I bought the DFRobot dual H-Bridge L298N and using their code, the motor doesn't rotate, just jerks back and forward 1 step. (The H-Bridge is stealing too much voltage I believe)

I also bought the cheaper 28BJY-48 5v Stepper with ULN2003APG driver, now this works, it rotates fine using the standard Arduino stepper code, the problem is that it slips, if I set the code so it takes 8 steps clockwise and then 8 steps counter clockwise all goes well for a few minutes and then I suddenly notice it's about 90º from where it started, I suspect the driver

So my questions are

1) a recommedation for a driver for the Mercury Motor Bipolar stepper 2) I'm also quite willing to build my own driver if anyone can point me to the correct type of circuit. 3) Where can I learn more about bipolar stepper theory, google is directing me to a lot of low information sites.

I have the same SM-428YG011-25 motors and I use Pololu A4988 stepper drivers with them. Be sure to set the current limit on the A4988 to match the motors or the smoke will escape.

Have a look at Stepper Motor Basics and this Simple Stepper Code

…R

Hi Robin, that was a good recommendation (Pololu A4988 Stepper Driver €6), thanks, the document site has all the info well presented and so I soon got it working with the Mercury Motors SM-428.

One thing that threw me, and I'm still not clear about is the digitalwrite for the stepper, the problem I'm having is that the motor springs into action if I put my finger, or mutimeter on the stepper pin, but not with digitalwrite from pin 7 of the ATMega 2560. So I'm using analogwrite on another pin until I can figure out what's happening.

I set up the driver current as recommended and the driver does not get hot, however, the motor does get extremely hot but I notice that it's possible to turn off the driver FET's in code while the motor is idle so that will probably reduce the heat.

Tim9vm: One thing that threw me, and I'm still not clear about is the digitalwrite for the stepper, the problem I'm having is that the motor springs into action if I put my finger, or mutimeter on the stepper pin, but not with digitalwrite from pin 7 of the ATMega 2560. So I'm using analogwrite on another pin until I can figure out what's happening.

I don't know what you mean by "the stepper pin"

I can't see the program that is exhibiting that behaviour. Please post the code that YOU have uploaded to your Arduino.

The Arduino function analogWrite() has nothing to do with stepper motors.

...R

Of course, If I hadn't been in such a hurry I would have remembered to set pinMode as OUTPUT and everything would have worked fine from the start. :confused:

That was the source of the problem, now it does perfect 180º forward and reverse from the digital pins. :)

Tim9vm: Of course, If I hadn't been in such a hurry I would have remembered to set pinMode as OUTPUT

You are not the first (or the last) to make that sort of mistake. Welcome to the club.

I hope you will now see the value of posting your code when you have a question.

...R

disabling power to the stepper is fine if you don't care if it moves but if it is holding something up an unpowered stepper will turn if forced