Transistor Help

Discussion in 'General Electronics Chat' started by bsfrye, Feb 26, 2009.

  1. bsfrye

    Thread Starter Member

    Feb 20, 2009
    23
    0
    I want to use a transistor to switch on and off a 6 volt dc motor (7 amps max) using a microcontroller. Thta's it - nice and simple... On and off. Will this transistor do the job? The current ratings are fine, but I am not familiar with all the other stats. Will a microcontroller be able to "turn on" (sorry, don't know the actual term) the transistor, and will it be ok with running 6 volts trhough it?

    MJE2955T

    http://www.farnell.com/datasheets/64761.pdf
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The motor needs 7A but a PIC micro-controller can supply only 25mA.
    A MJ2955 or 2N3055 needs a base current of about 1.75A to saturate with a 7A collector current. 70 times more than the PIC can provide. The transistor has a high voltage loss to the motor.
    Use a logic-level Mosfet instead.
     
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