how to change negative pulse to positive pulse?

Discussion in 'General Electronics Chat' started by radetonator, Sep 22, 2011.

  1. radetonator

    Thread Starter Member

    Aug 1, 2011
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    For the pulser circuit shown below, the output pulse is negetive. If BNC need to be connected to the load, how can output pulse be positive?:confused:
     
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  2. MrChips

    Moderator

    Oct 2, 2009
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    Use a single stage common emitter circuit with an NPN transistor, similar to the one shown in your circuit.
     
  3. RRITESH KAKKAR

    Senior Member

    Jun 29, 2010
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    Use transistor or MOSFET ....
     
  4. radetonator

    Thread Starter Member

    Aug 1, 2011
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    What if the voltage is 1KV, pulse duration is 1ns?
     
  5. RRITESH KAKKAR

    Senior Member

    Jun 29, 2010
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    Then i think it will be not easy...!!
    or use step transformer ( Fly back)
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    What in the world are you working on that outputs a 1nS -1kV pulse?

    I hope you realize that a 1nS pulse will require a circuit with a bandwidth >= 10GHz in order to make a reasonable facsimile of the pulse, but inverted, right? That's in the radar X-band RF spectrum. At those frequencies, a tiny kink in a wire acts like an inductor. It's even difficult to use multilayer ceramic caps due to their parasitic inductance.

    In the beginning of your thread, you posted a waveform that's practically identical to the one in this thread:
    http://forum.allaboutcircuits.com/showthread.php?t=59546
    and the OP is wanting to invert the signal, stretch the pulse, and detect it using a microcontroller.
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    Looks like some kind of charged particle or gamma-ray detector.
     
  8. ahsansahab

    New Member

    Sep 22, 2011
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    use an emitter follower op amp.
     
  9. MrChips

    Moderator

    Oct 2, 2009
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    Emitter follower does not invert.
     
  10. radetonator

    Thread Starter Member

    Aug 1, 2011
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    The pulser i am working on is not the one as shown in the beginning of the thread. But the structure of the output stage is the same-- a capacitor and a load resistor. The current flows from GND to the load. So that pulse is negative.
     
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