hay!
I'm trying to run some stepper motors with my Arduino. I took the motors from an inkjet printer.
They are both rated at 27V, one at 4 ohm, the other at 41 ohm.
I was building a darlington thingy with TIP31C transistors to accomodate them when it came to my mind that my benchtop power supply gives a maximum of 15 volts at 6 amps.
Since I'm a beginner I have some sort of a right to ask questions with obvious answers; can I drive these motors with my power supply at 15v?
Thanks
You can probably make them run, but you may not achieve the torque you could get from them with the higher voltage.
They are both rated at 27V, one at 4 ohm, the other at 41 ohm.
Are you sure about 4R because that gives you a current of just over 6A which is a lot of current for a printer. Has the 1 been rubbed off something? Have you measured it?
27V at 41R gives you a stall current of 660mA which is much more reasonable. At 15V you would have a current of 365mA which is just about half the maximum current so I would say yes it will turn but you won't be able to get it to go as fast as it would with 27V.
Well, if it's not 4R its a mistake on the sticker, it's very clear 27V 4R. It's the motor used for driving the gearbox that deals with the overflowing ink tampon and paper feed.
Should I avoid running this motor?
Could I use it for short temporary actions without damaging my Arduino?
I'ts a little scary, so many people warn you that the world AND your Arduino will explode if you misconnect or misuse something...:0
Would it be ok to use the 2 ports of the power supply to double the voltage? Any danger here?
Thanks a lot!
I haven't seen many stepper motors print the resistance on the nameplate (more common is the current), so maybe the 4R doesn't mean "4 ohms" but....4R. 4 wires? Model "4R"? Who knows....probably best to just measure the wire leads with an ohmmeter.
I agree that 27V and 4ohms --> 6.75A/phase is a bit excessive for a printer motor.
If you only apply 15V to it, the current will be less. If the Arduino is controlling it through a transistor, it shouldn't damage the Arduino (though I can see the transistor catching on fire...best to use a MOSFET or dedicated stepper motor driver rated for that kind of current).
Some power supplies with 2 ports have pushbuttons that let you place the 2 ports in parallel to increase the current. Is that what you mean?
What's written on the motor is 4 followed by an "Omega" greek letter.
It goes like this:
QH4-4410
SMH42-9609-A
27V
4 'Omega' 173T
FDK
The other motor from the same printer has this:
QH4-4343
SMJ35-4817-A 17ST
27V
41 'Omega'
FDK
There are 3 outputs on my power supply, I was thinking of simply putting two of them in parallel... (2+ together and 2- together)There is no pushbutton for this... Good \ Bad Idea?
Putting the power supplies in parallel is probably a bad idea. If they're not designed to work that way, you may damage them.
OK, I guess it is 4 ohms then 
Still, if you drive it with a lower voltage, it will simply take lower current, and it will just not have as much torque and/or you can't go as fast.
Usually, paralleling power supplies is a bad idea. One of them will supply most of the current, since you will never get them to exactly the same voltage so one of them will "win". If you get them really really close, though, the resistance in the wiring you use might be enough "ballast" resistance to allow them to even themselves out.
Besides, you can just try it with one power supply first. Hopefully, it's a current-limited supply that won't burn up or be destroyed if you try to draw too much current.
world AND your Arduino will explode
It doesn't actually go bang, the most you will get is a pop like a book slamming shut. Blowing up is a word used in electronics for "not working any more because too much current flowed".
As said before don't connect two supply outputs together. I don't doubt what you say about the motors but have you measured it with a meter?
The other thing it could be is that it is not designed to run with that much current statically and that it is a special design of motor meant to take short pulses only. That is a technique where you can get a stepping motor to move very quickly but you have to power it down when it is not moving.