Stepper Motor not moving

Chuck Thomas

I am trying to make the parallax stepper motor turn. I am using parallax stepper motor (12-Volt Unipolar Stepper Motor (#27964)) and the ULN2803. It is wired according to the documentation (Stepper_motor_27964.pdf). I have double checked the wiring. The stepper kinda of moves back and forth in a jiggering motion. The only change in wiring was attaching the 12 volt ground with the Vss ground. I believe that either the coils are incorrect or the time·each coil is turned on is incorect. The color code for the stepper motor matches the documentation. Any suggestions?

Franklin

well if all is as you say you have bad hardware but I would suspect incorrect wiring. Check it twice.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Stephen

Chuck Thomas

Thank you, Franklin. Upon checking for the fourth time I realized my wiring error. The stepper is now rotating 180 degrees back and forth.

Chuck

hotrod

Hello, I am using the same setup, only my stepper motor is a 2phase motor. I am wiring everything, to my knowledge, correct according to the schematics by parallax. My motor is also jolting back and forth. What was the solution to your problem? My worry is that since the motor is 2phase, it needs a different code or a different wiring setup.

remmi870

two phase motors use two independant phases that run (posative, negative) (posative, negative)

to get the motor to move you need to run the power out like this
(+,--) (+,--)
(--,+) (+,--)
(--,+) (--,+)
(+,--) (--,+)
you may be able to use the uln2803, im not shure how the diode biasing will work, you could also use dual h bridges, the nice thing is you can condense the wiring down to two wires, one for each phase using a flip flop to run the h bridge, or the easy way would be to find a cheap stepper motor driver for bipolar stepper motors.