novice need help ...

Discussion in 'The Projects Forum' started by gigiduru, May 8, 2008.

  1. gigiduru

    Thread Starter New Member

    May 8, 2008
    2
    0
    I need help to design a current generator with variable adjustable current values but once adjusted needs to be constant, while the load (7.4 ohm coil) may become hot and change the resistance. The current needs to be adjustable between 100 to 700 mA ( a pot. or a resistor divider will do it), power supply 12V and operate at military or automotive specs.
    Any help will be appreciated.
    :confused:
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Get the data sheet for the LM317 adjustable regulator. One of the applications illustrated is for a current regulator.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    In particular, National's datasheet for the LM117/LM317. Look at the bottom of page 18.

    If R1=12 Ohms, Iout=100mA
    If R1=1.7 Ohms, Iout=705mA
    I suggest you use a 3-Watt rheostat for R1, with a 1.5 Ohm 2-Watt resistor in series.
     
  4. Digi Dave

    Member

    Apr 25, 2008
    26
    0
  5. gigiduru

    Thread Starter New Member

    May 8, 2008
    2
    0
    Thanks a lot guys...!
     
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