Wiring a MOSFET?

Discussion in 'General Electronics Chat' started by Solarius, Jan 28, 2007.

  1. Solarius

    Thread Starter New Member

    Jan 22, 2007
    9
    0
    Ok, I ordered some IRF620 MOSFETs and I want to use them to regulate a motor.

    I'm a little confused about how it works, however. So there are three pins... I know that they are source, drain and gate. Which is which?

    So, right... basically, I have a battery, a motor, a voltage source and a MOSFET, and I want to use the voltage source to control the battery power to the motor. How exactly do I wire that?

    Thanks so much!!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    I suppose they're in the TO-220 package. If so, the leads go Gate - Drain-Source with the markings facing you.
     
  3. voduychau

    Member

    Jan 3, 2007
    19
    0
    can we invert the Drain-Source of Mosfet?

    i think there're no difference,isn't it ?
     
  4. Solarius

    Thread Starter New Member

    Jan 22, 2007
    9
    0
    With the markings facing me, if I attach a battery and motor to pins 2 & 3, the motor spins. Wouldn't I need to attach the gate and create a voltage for that to happen, if those were drain and source?
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Most mosfets have an intrinsic diode. If you wire DS backwards, then current flows through the diode regarless of signal on the gate.

    At least until the diode overheats...

    So, no, they don't work properly when they are in backwards.
     
  6. voduychau

    Member

    Jan 3, 2007
    19
    0
    therefore,JFet(channel N & P) and MosFet(channel N & P) don't work properly in backward,too ?
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Technically, they can. It is bad practice except in special applications. The "backward" mosfet should only be used in such things as battery reversal protection. To assume that polarity is not important is to invite burned up components!
     
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