Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: parthik on March 17, 2008, 08:36:20 AM
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I am driving a unipolar stepper motor with a ULN 2803 and a avr ATMEGa32
the problem is that i have to increase the current input to the stepper motor to 1.7A(each motor) to make it run .
But the rating of ULN is 500mA which made me burn many ULN's...
My friend runs steppermotor using 1A(for both motors).
also can u show me a ULN circuit diagram? cause I have got it from a book so not sure if it would work. ....
I am using a 9v stepper motor and .8A current but when i fit the wheels , the stepper doesnt move until i increase the current upto 1.7A.
PLz help
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If the ULN can only let 500mA pass, another circuit won't increase that...
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but how cme my motor consumes so much current?...
its a minebea unipolar stepper motor .
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make a power stage with 4 transistors, or if you wish to do bipolar stepping, with two h-bridges.
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but how cme my motor consumes so much current?...
its a minebea unipolar stepper motor .
-because that's just a characteristic of that type of motor.
-because the motor shaft is jammed and the motor stalls.
-because you connected the the motor wires wrong.
choose one ;)
I suspect the last choice most.
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here is a circuit showing a uln2003 driving a motor, it connects the same as the uln2803.
(http://www.cs.uiowa.edu/~jones/step/examplef/3.gif)
Ignore everything in the diagram but the uln2003, and just connect your microcontroller outputs to the left side of it where the 4 wires are now.
The 500ma rated current for the darlington array is for a single darlington set(pin), so if you had a couple of darlingtons you can probably connect them in such a way as to share the load between more than 1 pin. Before you do this, definately make sure that your stepper is connected properly otherwise it will just increase current draw
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check the datasheet to see if stacking is allowed.
you could put them on top of each other and double the ouput
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pls use driver with 4 transistor or attach 4 ic in parllel