7805 regulator, current source

Discussion in 'The Projects Forum' started by tammea, Sep 21, 2012.

  1. tammea

    Thread Starter New Member

    Sep 21, 2012
    1
    0
    I am doing a project where i am to design a constant current source using a 9/10 Volts regulator of a 78xx series regulators.

    The problem i encounter with this circuit is that the current is not constant. i have connected 24V at the input of the regulator, then connect the com/grnd to output voltage through my current producing resistor. the com/grnd of regulator is connected to ground of supply( 24V ) through my load. with constant current flowing i am aspiring to measure the voltage across the varying load at constant current. the data sheet says it should work, but it doesn’t.
     
  2. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
    764
    Show your complete circuit.
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,394
    1,606

    What would "it doesn't (work)" mean?

    -“When things are acting funny, measure the amount of funny”. (Bob Pease)

    (Complete aside: I just followed a link to some of Bob's wisdom and discovered this is NOT his quote, he is quoting production test manager Tom Milligan, and he calls this phrase “Milligan’s Law,” in his honor.)
     
    Last edited: Sep 21, 2012
  4. RamaD

    Active Member

    Dec 4, 2009
    254
    33
    You probably need a cap between the 78XX O/p and Ground Terminals as recommended!
     
  5. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
Loading...