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Author Topic: 5v 28YBJ-48 Unipolar Stepper Driving Me Mad!  (Read 2978 times)
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Cornwall, UK
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Hi again all,

I purchased a couple of these steppers http://www.ebay.com/itm/220869543972?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648. I fished out a ULN2003A and stuck it on my breadboard and wired it up according to the schematic in the Arduino playground and the wiring instructions from the description of the above link which state:

"Wiring Instruction : A (Blue), B (Pink), C (Yellow), D (Orange), E (Red, Mid-Point)"

I've attached my schematic below.

I uploaded the 'stepper_oneRevolution' sketch from the stepper examples in the ide, add changed the code below to 64 steps as according to the info given these have a step angle of 5.625deg. So 360/5.625 = 64 steps.

Code:
const int stepsPerRevolution = 64;  // change this to fit the number of steps per revolution
                                                        // for your motor

After several attempts and searching through the forums trying a couple of different combinations for the outputs of the arduino, I am unable to get this motor to do one complete revolution in 64 steps!!

Angrily (tired at this point), I picked up my mini vice and with a well aimed (all be it accidental) shot, managed to put a rather large dent in my guitar!! LOL.

So just wondering if anyone can shed light on how to get these motors working!!

Thanks.



* myStepper.JPG (67.82 KB, 1044x564 - viewed 71 times.)
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If the data sheet is to be trusted it has a resistance of 130R this only gives a current of 38mA which is small.
Is the motor turning consistently through a specific angle? Have you slowed it down, if they go too fast they skip pulses. You could try a higher voltage,  like that on the Vin pin if using an external power supply.
« Last Edit: December 08, 2011, 01:06:30 pm by Grumpy_Mike » Logged

Cornwall, UK
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Hi again Grumpy_Mike,

It turns, but tiny amounts, def not 5.625deg. Ill have a play with your suggestions in mind.

Thanks
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I guess it is too late to say as you might have already found the answer, but.. I had the same problem too. I read many forums and I ended in the conclusion that there is somethin going on with the gear reduction. It seems that (it worked for me) you have to go up to 2048 steps for a full 360 degree rotation. You also have to set speed at 200 max as the gear reduction won't let it speed up more. And double check the sequence too.
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Angrily (tired at this point), I picked up my mini vice and with a well aimed (all be it accidental) shot, managed to put a rather large dent in my guitar!! LOL.


Sounds like someone needs to grow up or get some anger management classes... Sure wasn't worth the mark in the guitar and didn't help the vise any...

How far was it turning? Was it repeatable. Those 2 will give you quite a bit of the answer of whether it is working. Next is - How fast are you stepping? If you are stepping too fast you WILL miss steps. Could just about drive this one directly from the Arduino - just add diodes across the windings. (Diodes won't conduct when the Arduino is at 5 V.)
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64 steps per turn of the motor.  There is a 64:1 gear so the shaft will only rotate 5.6 degrees...
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