increase hysteresis for gate driven by hall? (with schematic)

Discussion in 'General Electronics Chat' started by Hamlet, Sep 21, 2019.

  1. Hamlet

    Thread Starter Member

    Jun 10, 2015
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    I need to increase the speed by which it turns off (turn on is a little too slow too)

    All I have are my eyeballs to evaluate the speed, and it seems slower turning on, than off, persistence of vision not withstanding.

    DSCF4502 hall slow switching.JPG

    I want to pair up this circuit, using two hall sensors, back to back, so that when a magnet turns one off, the other is turned on, and finally,
    mate the signals to an H-bridge. (I'm trying to prevent shoot-thru.) Maybe it don't matter, cause hall sensors switch fast, so shoot-thru might
    only last a milisecond?? What do the brains think?
     
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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  3. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Make the 10M a 1K resistor, the fet Gate is high in capaitance.
     
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  4. KeepItSimpleStupid

    AAC Fanatic!

    Mar 4, 2014
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    For turn-off, you need a gate resistor to ground.

    For the ultimate in speed, you need a gate driver to overcome the gate capacitance. The voltage across a capacitor can't change instantaneously hence, some slowness. Your not actively or passivly draining away gate charge when you turn it off either.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Something like this?
    upload_2019-9-22_9-30-56.png

    Max.
     
  6. Hamlet

    Thread Starter Member

    Jun 10, 2015
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  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    A way of discharging the Mosfet gate capacitance quickly.
    Max.
     
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