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Voltage wabbler

Discussion in 'The Projects Forum' started by RANDALLMAN, Sep 17, 2011.

  1. RANDALLMAN

    Thread Starter New Member

    Sep 15, 2011
    1
    0
    HELLO,

    HELLO I NEED A CIRCUIT THAT WILL RAMP FROM 0 TO 12vdc IN 1/2 SECOND THEN RAMP DOWN FROM 12VDC TO 0 IN 1/2 SECOND the load is .5 amp, (Voltage Wabbler) This circuit does not need to be precise, some adjustment for the time using a trimmer pot would be nice. Basically it would be like turning a potentiometer up and down over a 1 second period, This circuit would be turned on by a 555 timer and would free run as long as the timer signal output is on.

    Any help is appreciated

    Randallman
     
  2. #12

    Expert

    Nov 30, 2010
    18,076
    9,691
    Hello. Glad you know what a 555 is.

    The way to get a good ramp is to make a constant current supply fill a capacitor. What you're going to need is 2 constant current supplies connected to a 555 timer. One to fill the capacitor and one to empty it. The usual 555 circuits already have a kinda ramp, but it's an exponential because it's a constant resistance into a capacitor. The output of the ramping 555 will have to use a power transistor to supply the current.

    There's a clue. I'm too lazy to design it for you. Take a shot and show us what level of understanding you have. Then the conversation can progress.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    21,838
    3,047
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