Could someone explain to me where a unl 2003 darlington array sinks the current to when used to drive a stepper. I assumed it would be to the ground pin. I am using the e labs stepper control chip ede1200 and its getting hot like it is sinking the motor current. I am trying to run a unipolor 6 wire 6v 9ohm/phase at 12 volts with 2 current limiting resistors per motor 10 ohms/10 watts. Right now I am clocking with a simple 555 timer at very slow speeds like 2 hertz. 2 outputs from this transister array should sink 1 amp and work fine for what I want to do. I am using a pc power supply with 5 volts for the chips and 12 volts for the motor.
I am also measuring 7 to 8 volts at the inputs to the array for the 4 phases. I had assumed the controler would put out logic level.
This setup is turning the motors in time with an led driven with the clock pulse but Im getting no torque at all plus the heating problem in the stepper control chip. In the printers I took these motors from the gears would eat your fingers off if you tried to stall then. It looks like the printer is running these motors from + and - 14V (28volt across pins where motor plugs in) with some kind of current limiting beyond simple resisters. I did measure 700 mA per phase in the printer.
Im wanting to build a hot wire foam cutter for planes which wont require much torque or speed and if I can get the motors to work like they do in the printer they will be fine.
I also have access to a dual trace scope to if I knew what to look for.