How to trigger a 555 mono with a +ve pulse?

Discussion in 'The Projects Forum' started by onlyvinod56, Mar 5, 2011.

  1. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    hello,
    This is a cascaded multi level inverter.
    Iam trying to design a firing circuit based on 555 monostable, 555 astable, NOT gate, and optocouplers.
    see the attachments

    attachment 1: schematic of 2 level cascaded multi level inverter

    attachment 2: firing scheme

    attachment 3: my problem

    How can i trigger the monostable with the pulse shown in attachment 3??

    thankyou
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Just double checking, you want to trigger a 555 monostable with a positive going pulse? A simple transistor inverter in front of a conventional monostable would do this, or any inverter for that matter.

    [​IMG]
     
  3. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    ThanQ Bill_Marsden

    And one more question (just for conformation)
    How can a long duration pulse can be converted into a spike using RC circuit?? see the attachment

    Can u post the schematic
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Direction of flow for schematics is important, it can make a schematic hard to read or easy.

    Basically the capacitor charges up, and no more current flow, so the resistor then predominates.
     
  5. onlyvinod56

    Thread Starter Active Member

    Oct 14, 2008
    362
    1
    OK.
    It is a part of the schematic. Thats why the direction is reverse.

    And, I got your point. I have done the simulation.
    Thank you Mr. Bill_Marsden
     
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