Square wave inversion help

Discussion in 'The Projects Forum' started by gaganaut, May 31, 2010.

  1. gaganaut

    Thread Starter New Member

    May 27, 2010
    I am working on a project which requires us to have a dipole with oscillating polarities. So I am planning on using a square wave for this purpose.

    For generation of the square wave of 1V P-P, 1kHz, I used a circuit with 2 NPN transistors shown in the attached figure. This will take care of switching the polarity of one of the two poles. Now for the second pole, I need another square wave that is synchronous with the first one. I figure that a similar circuit with some tweaking won't help as the two signals cannot be guaranteed to be synchronous. Not that I know the tweaking to be done anyways.

    So I think if there was a neat IC that could invert the square wave, it would have helped. I looked up certain Charge Pump inverters.

    Q1. Can a square wave be inverted using a charge pump inverter?

    But I was not able to find an actual IC that could operate at an input voltage as low as +/-0.5V.

    Q2. Is there any other way to do what I want to do or a better IC that could do it?

    Any help would be really appreciated.

  2. beenthere

    Retired Moderator

    Apr 20, 2004
    If you double the voltage out, the effect will be the same as driving the other electrode with a mirrored waveform.
  3. SgtWookie


    Jul 17, 2007
    Try it like the attached schematic.

    R4 and R5 are 100k resistors in parallel to make 50k, because 50k is not a standard value for fixed resistors.

    It's not a perfect square wave output. However, it's pretty good.