My 12v, 8amp power supply for a project involving three dc motors, three servos, LED's, etc. has proven too much current for a bipolar and unipolar stepper motor. I ordered, and promptly fried two Pololu drivers so it appears running these steppers from two separate wall warts is a last ditch solution, assuming there is no simple method of adjusting current from the 8amp PS. Are multiple supplies a common alternative to powering steppers within a complex project? Also, using the minimum necessary supply, the unipolar stepper runs very hot while the UNL2003 remains cool. The SN754410 is also hot. Ran both for an hour without incident but question their longevity? All grounds are joined.
ifugaopapercraft:
My 12v, 8amp power supply for a project involving three dc motors, three servos, LED's, etc. has proven too much current for a bipolar and unipolar stepper motor. I ordered, and promptly fried two Pololu drivers so it appears running these steppers from two separate wall warts is a last ditch solution, assuming there is no simple method of adjusting current from the 8amp PS. Are multiple supplies a common alternative to powering steppers within a complex project? Also, using the minimum necessary supply, the unipolar stepper runs very hot while the UNL2003 remains cool. The SN754410 is also hot. Ran both for an hour without incident but question their longevity? All grounds are joined.
Your mistaken in your concept of current capacity of a power supply Vs what a given circuit might draw from that power supply. Your AC outlet in a room can supply up to 20 amps of current but you can certainly plug in a night light that might draw only 1/10 of a amp from the wall circuit.
So whatever your problem is it won't be solved by using a power source of less current capacity. If you are 'frying' motor driver modules then you are using motors that draw too much current from the driver boards, it's not your power supply fault, it's that you have improperly selected your motor driver / motor choice.
Typically the selection process goes as follows:
- Select motor that delivers the mechanical power required by whatever the motor is coupled with.
- Select the motor driver that can handle the voltage and maximum current draw of the motor.
- Select the power supply that can supply that voltage and is rated for a least the maximum current required by the motor, but more current capacity in reserve is better.
Lefty
Thank you for the explanation. I think the Pololu drivers were fried when I disconnected the motors while the board was still powered up. After reviewing dozens of stepper tutorials, would it be safe to say that UNL2003 (unipolar) and SN754410 (bipolar) can handle ANY stepper if they are piggybacked http://www.starlino.com/wp-content/uploads/data/motor_driver/IMG_1084.JPG until their collective max current surpasses that drawn from the motor, and running at the minimum designated voltage?
