current limiter using MOSFET

Discussion in 'General Electronics Chat' started by Skubby SkinnyChubby, Jun 19, 2015.

  1. Skubby SkinnyChubby

    Thread Starter New Member

    Jun 19, 2015
    25
    1
    Hi all,

    i want to create a current limiter circuit using MOSFET but i got no idea how to design,so can anyone guide/help me?

    details:
    24v input to the current limiter circuit and a 9A at the output to drive a load

    thanks a lot :)
     
  2. Skubby SkinnyChubby

    Thread Starter New Member

    Jun 19, 2015
    25
    1
    BUMP
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,027
    3,236
    Does the load need to be grounded?
    What is the maximum load resistance?
    What current accuracy/stability do you need?

    Bump: My, you are impatient. 47 minutes is a rather short time to expect an answer. :rolleyes:
     
  4. Skubby SkinnyChubby

    Thread Starter New Member

    Jun 19, 2015
    25
    1
    what do you mean by current accuracy/stability?

    sorry i'm very new to electronics
     
  5. crutschow

    Expert

    Mar 14, 2008
    13,027
    3,236
    You said you want the current to be 9A.
    Since no circuit can give a exact output it has to be designed to meet some tolerance on the current such as ±1ma, ±0.1A, ±1A, etc.
    The tighter the tolerance the more complex and expensive the circuit required.

    How about the answers to my other questions?
     
  6. Skubby SkinnyChubby

    Thread Starter New Member

    Jun 19, 2015
    25
    1
    i only know the circuit will be connect to a DC motor and the expected output is 9A max.

    this is all the information given to me..sorry :) :(
     
  7. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    Begs the question? Why do you think you need to limit the current? A DC motor limits its own current (look up Back EMF).

    Get a data sheet for the motor, and post it...
    (without a data sheet, you are guessing, so is your boss, and more importantly, so are we...)
     
  8. crutschow

    Expert

    Mar 14, 2008
    13,027
    3,236
    Are you trying to limit the motor startup current?
     
  9. Skubby SkinnyChubby

    Thread Starter New Member

    Jun 19, 2015
    25
    1
    yes
     
  10. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    If you put a hard limit on the current the motor might not start at all or accelerate very very very slowly. It is normal for the startup current to be four or five times the running current. If the 9 A. is a startup current, then what is the running current? Help us out and throw us a bone!
     
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