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  1. #21
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    Re: 3 hall sensors speed measurement

    Don't forget the original advice: sprinkle generously small value low impedance (ceramic in other words) capacitors at critical points. I cannot guess the source of the high frequency noise, but a ferrite bead in series with the power supply (if you are using the same power supply to drive several independent modules) may be also a good idea. The plus point is that they are relatively harmless.



    •   Alt13th March 2018, 08:17

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  2. #22
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    Re: 3 hall sensors speed measurement

    Hello,

    i promised to come back with results, generally speaking things work much better than the old design.
    Bellow you can see the noise on the 3.3V line for the mcu, measured with the "original long crocodile wire" of the scope probe.

    The noise is somewhere at 20mVpk-pk, which is much better from ( 1..2V pk-pk)

    I have the same values on multiple GND places accross the pcb. Tomorrow i will try to measure the hall signals, right now the system seems to work much better


    Click image for larger version. 

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    bellow you can see the large density of ceramic caps placed across the power stage ( 10nF + 4.7uF between each highside-Lowside mosfet rail)



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