Stepper doesn't Work

So i bought a stepper motor which is rated for 12v 1.2 amp.i connected it with pc power supply.pc power supply pin is rated at 12v 20a.but when i connect the motor it draws 2.4 amps.and it gets hot.i used uln2003 driver that’s rated at maximum 12 volt 500ma.so it can’t drive the motor.what can i do ?

Have a look at Stepper Motor Basics - it has a lot of background info which may help to sort out your problem.

Post a link to the datasheet for your motor. Without that I can't suggest a suitable driver. But (as you have figured out) it won't be a ULN2003.

...R

Robin2:
Have a look at Stepper Motor Basics - it has a lot of background info which may help to sort out your problem.

Post a link to the datasheet for your motor. Without that I can't suggest a suitable driver. But (as you have figured out) it won't be a ULN2003.

...R

sorry.couldn't find a datasheet on that motor.this is all i could find.

Specifications:
Product Name Stepping Motor
Model No. 42BYG47-01
Step Angle 1.8°
Rated Voltage DC 12V
Rated Current 1.2A
Motor Resistant 3.1 Ohm
Rated Speed 1200RPM
Shaft Diameter 5mm/ 0.22"
Motor Part Size (Approx.) 41 x 41 x 47cm/1.6" x 1.6" x 1.8"(LWH)
Cable Length 54cm / 2.1"
Mouting Hole Dia 2.5mm/0.1"
Material Metal, Plastic, Electronic Parts
Color Black, Silver Tone
Weight 352g
Package Content
1 x Stepping Motor

It is normal for stepping motors to get hot when run at the maximum rated current. Up to 80 degrees C is usually OK.

You need a modern motor driver, like one of these.

jremington:
It is normal for stepping motors to get hot when run at the maximum rated current. Up to 80 degrees C is usually OK.

You need a modern motor driver, like one of these.

but will it work with my motors ?

i bought a stepper motor which is rated for 12v 1.2 amp.

If that is correct, yes.

These figures are somewhat suspect

Rated Voltage DC 12V
Rated Current 1.2A
Motor Resistant 3.1 Ohm

If the coil resistance is 3.1 ohms (have you checked this with your multimeter?) and the rated current is 1.2 amps I would expect the voltage to be 3.72v, not 12v.

Assuming my maths is correct I would expect to be able to drive the motor with 24v or 36v (or more) as long as the stepper driver was set to prevent the current exceeding 1.2 amps.

Assuming my maths is correct if you apply 12v to the motor without a current-limiting driver the smoke will probably escape because the current could rise to 3.87 amps

...R

Robin, I'm not sure those specs apply. The OP said:

couldn't find a datasheet on that motor.this is all i could find.

Hyprex could you explain what you mean by the above?
Where did you find that information, and does that information apply to your motor?

Its a low impedance stepper - you should be using a chopper driver. DRV8825 for instance.

The 12V thing in the specs is entirely bogus, ignore it, steppers are rated by current and
normally current driven.