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Topic starter
2024-03-28 12:01 am
Hi
I have a working 28byj-48 with a ULN2003 in unipolar mode. If I remove the 5th wire from the motor and convert it to bipolar mode what changes do code do I need to do. Need a bit more torque.
Thanks
Charles
2024-03-28 1:39 pm
Hi Charles @sswcharlie,
Sorry, I do not claim any special expertise on motors, but I don't think you can convert the wiring to unipolar, because the two coils are joined by the common '5th' connection, that you have probably connected to the +5V supply.
This diagram from https://pdf.utmel.com/r/datasheets/mikroelektronika-mikroe1530-datasheets-3320.pdf shows the wiring you will have:
This diagram from https://buildbotics.com/wiring-stepper-motors/ shows the wiring for a bipolar stepper motor. Note the two coils are electrically isolated from each other.
The torque is related to the current in the coils, but simply increasing the current through the same motor means more heat. I fear you need a 'larger' motor that can handle a higher current, without overheating.
Motors in the Nema 17 size range are commonly used in projects discussed in this forum, and also widely used in the low-cost 3D printers. Some models are readily available for a few dollars, but they are obviously considerably larger and heavier than the 28byj-48
Alternately, a reduction gearbox will increase torque, at the expense of reduced speed.
Best wishes, Dave
Ron reacted