I have a 4 phase, 2 com unipolar stepper motor and a selection of hardware.
Could I run the motor using an Arduino Uno from digital I/O ports 8,9,10 and 11, and a ULN2004A? The motor is rated at 12.7v, 0.19A with a per phase resistance of 26.7?. Taking that the ULN2004A has a collector current rating of 500mA, and the motor will draw 475mA (12.7/26.7) per phase, should this be OK?
I simply want the motor to turn one way, then the other, in order to operate a homemade linear actuator.
Please forgive me if I am wrong on any count, but this is my first foray into electronics!
Parallel 2 channels per winding, so use the ULN2803 which has 8 outputs, not 7.
The absolute maximum current per channel is 500mA, you would never use the
chip at this current, the datasheets show only upto 350mA per output for
any parameters, so using 250mA per channel is reasonable. The chip should have
a small metal heatsink glued on top at these power levels really.
These devices have enough internal resistance to permit paralleling like this
I think - the resistance forces fair sharing of current between paralleled channels.
Time is short where this project is concerned (it forms part of an engineering degree presentation, due soon!), so would it be possible to put a 10 Ohm resistor in series with each phase prior to the chip thereby increasing phase resistance to 36.7 Ohms?
Would a small rectangle of aluminium make a suitable heat sink?
Thanks again
Edit: scratch that, I found a ULN2803A at work. Although just out of interest, would the 10 Ohm resistor method work? Just for reference.