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Stepper motor driver? Answered

Hi! I am trying to find a good h-bridge for a 3 volt stepper motor. Basically my plan is to build a stepper motor controller with an arduino for controlling various functions in a model kit. I have the arduino-kit and the motors.
But I need a good reference for a h-bridge, but all i can find are chips rated for much larger drive currents. Also exactly how hot does a hbridge get when under load? I would like to integrate the bridges into the kit, but since it is plastic, I would like to know in advance how hot it gets, and if it gets too hot I'll have to look at another solution.
Any help appreciated!

PS. If you can please put the hbridge part ID in your answer for easy reference. DS.

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Downunder35m

9 days ago

There are lots of shields available for stepper motor drivers but for a single one you can just wire them to the Arduino pins.
They cost about 3 bucks each, so nothing to worry here, same for the currents - a motor only draws what is needed but not what the supply is cabable of.

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Downunder35mfeldreich

Reply 9 days ago

Google is your friend....
https://www.norwegiancreations.com/2014/12/arduino...

You need a driver and for Arduino there are plenty that are "ready to go".
Some are dead simple and tiny, others, like in the above example a bit bigger.

How do you know your motor is for 3V?
Quite low, so quite tiny I guess, like from an old computer drive maybe?
Either way, should not matter much as most of these drivers can operate at less than 12V and your motor should be fine with more than 3V too.
The key is to turn the current down with the potentiometer on the driver.
Start with some simple example code and let the motor run.
Very slowly increase the current regulation if the motor is not spinning already.
Once it does apply a slight load to confirm it still spins.
For a tiny motor just touch the drive shaft with your finger ;)

Of course you should make sure to wire all properly and correct, same for making sure the code and libraries used are correct ;)

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feldreichDownunder35m

Reply 8 days ago

Yep 3 volts. I actually bought them new, from a now defunct site. The problem with them was that the site did not have any datasheet or data what so ever on the engine. Except the 3 v data. So really a lesson in how not to buy stuff.
If I was in the states things I guess would be much easier, but now I am in Sweden so all special electronic stuff is very hard to come by... Some of the manufactures don't ship.
The project is to make a plastic model articulated, actually a Tarangus Viggen in the 1/48 scale. So that is why I bought them. They are the only thing that is tiny enough to fit into the body. I was thinking servos for a while, but those are simply to big to be fitted inside the body of the airplane. So I really need to find a small enough circuit, as space is the main problem for the build. Alternatively I it could be possible to hide the chips in the base and have a pipe (or rod) run the cables to the motors in to the model. The cleanest build is however to run everything inside of the model, but I don't know if it is possible.

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Downunder35mfeldreich

Reply 8 days ago

I still don't think the voltage would be a problem.
Check Ebay for example with some links to the Arduino help and Playground sites.
Those drivers supposed to be mounted on a motor shield are half the size than what was in my last link.
And datasheets are available for them as well.
If in doubt you can always use a bench or lab power supply and check how far down you can go with the supply voltage for the driver without loosing function.

In theory sets of anti-paralell zener diodes for 3.3V in the motor lines should work too for this tiny one to keep the voltage low.

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feldreichDownunder35m

Reply 8 days ago

I'll have a look. I'll try ebay and after that zeners. Our toll on electronics from abroad is ridicoulus here in Sweden so hopefully I can find a local ebayer...

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Downunder35mfeldreich

Reply 8 days ago

Trust me, it is not much easier in AU :(
Local prices are outrages and you never find what you need....