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Topic: 24V stepper trouble, too many fried parts (Read 2 times) previous topic - next topic

TBCal

So I have been trying to run a 24v stepper with my arduino uno to no avail. I have already fried 2 sparkfun easy drivers this week and one SN754410 trying another circuit. I have been scouring the internet for help but have still had no luck. So here is what I have done:

I hooked up my uno to the easydriver following the diagram provided on the ED/sparkfun product page, plugged everything in and what resulted were sparks and smoke from the load supply pin of the A3967 chip on the ED. So I've done that twice thinking maybe I soldered something poorly and shorted something.

I also tried following the stepper motorknob arduino example (http://arduino.cc/en/Tutorial/MotorKnob) and that resulted in the exploding SN754410.

I should also mention I'm quite new to this stuff. But I would really like to figure out what I need to do run this motor and I am willing to put in the time and effort to make it work. So I would greatly appreciate any help either figuring out what I did wrong or what other approach I could take to make it work.
Below are links to all the pieces I used (motor, power, etc)

wiring - http://bildr.org/2011/06/easydriver/
motor - https://probotix.com/stepper_motors/ht23-260-4/
power - http://www.amazon.com/Universal-Adapter-15V-18-5V-19-5V/dp/B0027BUS0M/ref=sr_1_1?ie=UTF8&qid=1335829498&sr=8-1

dc42

Although the specification for that stepper says 12-24v, the current rating is 2.5A per phase and the resistance per phase is only 1 ohm. So the maximum steady voltage you may put across a winding when it is not stepping is 2.5v. The 12 or 24V only applies when it is stepping very fast, it's not safe to put anything more than 2.5v across it unless you have current limiting in place. If you ran it from 12v without any current limiting, it would take around 10A, which is why your motor drivers fried. Note the caption "Constant current driver" in the graph on the datasheet.

One possibility is to drive it using a stepper driver based on the L298N chip, run from 12v, with a 4.7 ohm 10W resistor in series with each winding to limit the current to 2A. Alternatively, use a stepper driver with current limiting (for example based on the L297 + L298) and no series resistor.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

jwatte

I would recommend against the series resistor. Not only is a 10W resistor pretty expensive and bulky, but it also will work as a space heater -- it's very inefficient.
Get a "chopping" or "current limiting" stepper driver, and you'll be fine.

MarkT


Although the specification for that stepper says 12-24v, the current rating is 2.5A per phase and the resistance per phase is only 1 ohm. So the maximum steady voltage you may put across a winding when it is not stepping is 2.5v. The 12 or 24V only applies when it is stepping very fast, it's not safe to put anything more than 2.5v across it unless you have current limiting in place. If you ran it from 12v without any current limiting, it would take around 10A, which is why your motor drivers fried. Note the caption "Constant current driver" in the graph on the datasheet.


If you did some research before posting you might have noticed that the A3967 chip in the EasyDriver is designed precisely to drive a low impedance motor from high voltage, its a chopper driver with current sense built in - it should "just work" (although it can't produce anything like 2.5A so its seriously underpowered for that motor.)

I would suspect that it might be struggling with such a low impedance motor (there are better chopper drives with faster output stages for instance), or it has been mis-wired or misconfigured.

My immediate advice is to check all the wiring carefully, run from a lower voltage at first instance (minimum is 7V), and monitor the current (the Easy Driver can do 750mA or so to the motor).  Only if it behaves as expected do you ramp up the voltage.  No-one who has ever developed motor drivers has ever run at full voltage and power in their first test (something always explodes).

The real solution will be to use a beefy chopper driver that can handle 2.5A such as the L6208, otherwise you'll never get much torque out of the motor.
[ I won't respond to messages, use the forum please ]

TBCal




My immediate advice is to check all the wiring carefully, run from a lower voltage at first instance (minimum is 7V), and monitor the current (the Easy Driver can do 750mA or so to the motor).  Only if it behaves as expected do you ramp up the voltage.  No-one who has ever developed motor drivers has ever run at full voltage and power in their first test (something always explodes).

The real solution will be to use a beefy chopper driver that can handle 2.5A such as the L6208, otherwise you'll never get much torque out of the motor.


After what I did to that driver do you think there is any life left in it to bother trying running again at a lower voltage?
To be honest I think I would rather pursue the "real solution", that way it will work better in the long run and I will probably learn more in the process (which would be good since that newbie label by my username is definitely accurate  :) )
With that in mind can anyone make a suggestion as to an "off the shelf" driver board that would be more appropriate for my application or a tutorial/example on how to wire the entire circuit using something like the L6208. Although I looked at some documentation for it and it made rough sense, it would still be quite a task for me to wire it simply based of the schematic.

By the way, as I am new to this forum I appreciate the responsiveness of everyone and am thankful for your willingness to help out someone like myself who is quite early in the learning process.

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