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Old 15th May 2017, 1:54 PM   #301
dakiller
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So was playing with a stepper motor at school in the staffroom, (new one I hadn't used yet). Maybe I'd entered the wrong value of something, but it went up in smoke.
And now you need to work out why, and you will learn something from it.

(I don't know how you smoked a stepper, they should be pretty robust)
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Old 15th May 2017, 1:57 PM   #302
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And now you need to work out why, and you will learn something from it.

(I don't know how you smoked a stepper, they should be pretty robust)
Maybe it was already faulty?
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Old 15th May 2017, 4:23 PM   #303
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So was playing with a stepper motor at school in the staffroom, (new one I hadn't used yet). Maybe I'd entered the wrong value of something, but it went up in smoke.
Many stepper motors are rated for quite low voltages (eg 3V) so if you have them connected to a higher voltage supply like 5V or 12V you need to do current limiting. Smarter stepper drivers have this built in, dumb ones or H-Bridges do not and you can overheat the stepper. Depending on the size of the stepper this could take between a few seconds and several minutes.
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Old 15th May 2017, 4:30 PM   #304
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Many stepper motors are rated for quite low voltages (eg 3V) so if you have them connected to a higher voltage supply like 5V or 12V you need to do current limiting. Smarter stepper drivers have this built in, dumb ones or H-Bridges do not and you can overheat the stepper. Depending on the size of the stepper this could take between a few seconds and several minutes.
Hmm. The schematic I read said to attach the stepper to a 5volt pin. No resistors or anything... :S
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Old 15th May 2017, 4:52 PM   #305
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Hmm. The schematic I read said to attach the stepper to a 5volt pin. No resistors or anything... :S
a 5v pin? Of the Arduino? Is that the main power supply or one of the 4 "signal" pins?
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Old 15th May 2017, 5:18 PM   #306
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a 5v pin? Of the Arduino? Is that the main power supply or one of the 4 "signal" pins?
Soz socket. 5v socket. That I plugged the motor into.
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Old 16th May 2017, 11:38 AM   #307
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We need more info...

What is your power supply.
Where exactly did you plug the stepper into the arduino (hint, you shouldn't have)
Were you using a dedicated stepper driver module or a H-Bridge?

Photos would help heaps.

Last edited by aXis; 16th May 2017 at 11:54 AM.
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Old 16th May 2017, 12:22 PM   #308
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We need more info...

What is your power supply.
Where exactly did you plug the stepper into the arduino (hint, you shouldn't have)
Were you using a dedicated stepper driver module or a H-Bridge?

Photos would help heaps.
Admittingly i don't have much experiance with Steppers, but i didn't think you used an H-Bridge with a stepper.

You have to send it commands using 4 wires in a specific pattern to make it work, like

0101
0110
1010
1001
-repeat

i guess if you just powered it like a normal motor then maybe that would burn out?
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Old 16th May 2017, 1:37 PM   #309
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Admittingly i don't have much experiance with Steppers, but i didn't think you used an H-Bridge with a stepper.

You have to send it commands using 4 wires in a specific pattern to make it work, like

0101
0110
1010
1001
-repeat

i guess if you just powered it like a normal motor then maybe that would burn out?
Dangerously close, but no cigar.

Electrically, steppers are just a collection of coils. Like any coil of wire, when you put current through them they warm up. Keep the current within the ratings and they can run permanently with no damage.

Yes, the wires have to be fired in a specific sequence, but the Arduino does not have enough current sourcing/sinking capabilities to run them directly and will blow the arduino if you connect them directly. You can use a MOSFET or BJT circuit to improve the current drive, but in most common steppers the coils have to be bidirectional and this makes the circuit complicated.

A dual H-Bridge is a much more convenient solution and provides the minimum necessary functionality and increased power handling to energise both coils of a 4 wire bipolar stepper motor. The arduino can then drive the H-Bridge logic inputs in the above sequence.

Finally, for even greater convenience, you can use a dedicated stepper driver IC or module. It gives a simpler interface to the arduino with lower pin count, and often provides extra features like microstepping and current limiting. They are cheap - eg a Polulu driver that handles an amp or two can be found on ebay for under $2.

Last edited by aXis; 16th May 2017 at 4:34 PM.
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Old 16th May 2017, 9:47 PM   #310
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And now you need to work out why, and you will learn something from it.

(I don't know how you smoked a stepper, they should be pretty robust)
its easy to smoke/demag a stepper. 5 volt one plugged into 12 volts will usually murder them.

speaking from experience.

Another thing, depending on if its bipolar or unipolar, some steppers need 1 wire to power, and the others earthed in sequence, where others use H bridges. Some steppers also do both. Depends on how many wires it has.

4 wires are usually bipolar, requiring 2 h bridges, 5 or more can usually be driven by either type but you really should check the docs with the stepper.
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Last edited by rainwulf; 16th May 2017 at 9:50 PM.
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