I am using an SN754410 to drive a bipolar stepper using the typical 4 pin setup. On a breadboard, it works fine. On the project board, it doesn’t and overheats. The stepper rattles but does not respond to switches. This http://www.flickr.com/photos/50454200@N06/8595069215/ photo of the very poorly designed board will hopefully illustrate the problem. The Mega is powered by a 6v dc to dc converter from an 8amp, 12v power supply. The lower chip is an ULN2003 driving a unipolar stepper without a problem. I am hoping the photo will suffice. My schematics are amateurish as best. The breadboard circuit was powered by a 12v, 500 ma wall wort. Does this mean I have to add a current regulating component just for this driver?
Probably a wiring error, if it worked on the breadboard.
My first thought is the same as the above. My second is "Good luck finding it". :twisted: But I have one more thought ...crackle:
The Mega is powered by a 6v dc to dc converter from an 8amp, 12v power supply. The lower chip is an ULN2003 driving a unipolar stepper without a problem. I am hoping the photo will suffice. My schematics are amateurish as best. The breadboard circuit was powered by a 12v, 500 ma wall wort. Does this mean I have to add a current regulating component just for this driver?
How are you powering the ULN and stepper ? Presumably the breadboard powered the high current devices from the 12V, 500 mA wallwort. With the perfboard I hope they are powered from the 12V, 8A supply and not from the Arduino’s regulator.
Yes, the perf board is powered by the 12v, 8amp supply with Arduino ground and supply ground together. The small unipolar stepper on the ULN2003 runs very hot but without a glitch. I have desoldered again and again after reassembling the SN754410 on a breadboard, hoping to discover the error.
Yup, troubleshooting can be like proofreading … awfully hard to see your mistakes. This is where a schematic, even an amateurish one, can help. “We”** could devise a plan to measure (w/a DVM) various points that would likely isolate the problem. Frankly I can’t make heads nor tails from the picture and don’t envision taking the hours needed to try it.
**not to invoke the royal “we”
Here is a not so professional drawing. http://www.flickr.com/photos/50454200@N06/8597337363/