28BYJ-48 stepper too hot to touch - is 9v too much?

Version 2 of the myFocuser Project

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28BYJ-48 stepper too hot to touch - is 9v too much?

Forum: General Discussion

Creator: anthony bradley

Created: 5 days ago

Updated: 3 days ago

anthony bradley - 5 days ago

Hi,

I have built an FP2 using a 28BYJ-48 (which is marked as 5v) and its ULN2003 driver board (marked 9-12v input), and the FP2 circuit diagram shows the ULN2003 driver board powered by 9v, however, on long focusing runs the motor gets too hot to touch and melted the PLA adapter on the output shaft.

Should this be running at 9v, or should I reduce the power supply voltage to the driver board?

Thanks

Screenshot 2025-08-25 111009.png

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Dave Wilkes - 3 days ago

make sure coil power is set to off
these steppers get very hot when coil power is on all the time and as its geared you dont need it

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