issue with homemade DC motor + hall effect sensor

Soremade

Jun 10, 2026
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Jun 10, 2026
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Hi everyone,

I'm building a brushless DC motor for my students but I have an issue.

The tutorial I followed :

I recorded the issue right here :
We can see that the motor does not rotates entirely. I suppose the hall effect sensor does not send the order at the right moment but I don't know how to solve it. Any idea ? I'm quite frustrated cause I feel close to the goal.

The circuit I did is attached bellow.

Thanks a lot in advance,
Guillaume
 

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bertus

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Nov 8, 2019
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Could there be a problem with the mosfet.
It has a gate voltage threshold of 2 to 4 volts.
An irlz44 has a threshold voltage of 1 to 2 volts.

Bertus
 

Alec_t

Jul 7, 2015
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Could there be a problem with the mosfet.
I wondered about that, particularly as the circuit has no back-emf spike protection for when the coil current switches off. However, the power supply in the video shows switching between 0 and ~140mA, so presumably the FET is doing its stuff.
 

Soremade

Jun 10, 2026
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Thanks Alec, yes I've tried many different position with the sensor.
Unfortunately Bertus I won't be able to check that point before next week but thanks for your suggestion.
 
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bertus

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Is the orientation of the magnets (north / south) correct?
Is the polarity of the coils correct (is one of the coils the wrong way around)?
Did you try to hold the hallsensor the other way around?

Bertus
 
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