Hydraulic Valve Control Circuit with 0-5k pot control

Discussion in 'The Projects Forum' started by ZipperJeremy, Feb 2, 2009.

  1. ZipperJeremy

    Thread Starter New Member

    Feb 2, 2009
    1
    0
    I need a circuit that uses 0-14.5 Vdc to control a valve that is 20W (at 12Vdc). I purchased a 0-5K ohm electric bike handle grip. The grip looks like it can only handle 0.5 Watts. I have tried to use a 2SC4793 NPN transistor with a voltage divider to control the base. I am not having any luck with this. The transistor will only output 0-6 Volts. I used one transistor to power a second transistor but that didn't work very well either. Has anyone seen any circuits like this, or could you point me in a better direction?

    Thank you.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Can you post up the schematic of your circuit? We can make much better guesses with that in hand.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Try it like this:
    [​IMG]
    You'll likely need a heat sink on Q1.
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    I think a valve can only be switched on and off (not something intermediate), does it?
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Mik3, I think you're on to something.

    At least if it's a pressure regulator valve. A chopper circuit would be much more appropriate - and much more efficient - along with being much more complex.
     
  6. mik3

    Senior Member

    Feb 4, 2008
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    ZipperJeremy give more information about the valve or its datasheet.
     
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