Voltage shifting

Discussion in 'The Projects Forum' started by keithbrook, Jul 29, 2009.

  1. keithbrook

    Thread Starter New Member

    Jul 29, 2009
    Hi Lovely People

    I'm using a joystick to control a ready made motor controller.

    The input required is 0v to 5v with a centre point at 2.5v. However, the joystick, which is connected across a 0-5v tap from the controller, doesn't use the full potentiometer track and I can't reach anywhere near 0v or 5v.

    I feel that an op-amp used as a differential amp is the way to go, but all the circuits I've seen here rely on a small negative voltage to achieve 0v at the output.

    Is there another solution?

    In this motor control context, it'll be acceptable to not quite reach 0v or 5v.

    I should also mention that the motors are fed from a 12v supply, just in case a solution may be found by using, say, 0-9v.

    Thanks in advance for any help on this.

    Last edited: Jul 29, 2009
  2. lightingman

    Senior Member

    Apr 19, 2007

    Yes you will need a small neg voltage to achieve 0 volts. I do this quite often when building battery operated equipment. Just use an ICL7660.

    If you need more details, let me know...