Simple help - trigger output when low

Discussion in 'General Electronics Chat' started by Razor Concepts, May 26, 2009.

  1. Razor Concepts

    Thread Starter Active Member

    Oct 7, 2008
    212
    1
    I need some help. I think it is really simple but I do not really get it. When an output is high (+5v), a normal NPN transistor is driven. That works great. However, when the output is low, (0v), I want another transistor to be driven. How would I go about doing this? Thanks!
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    A PNP wired from the plus power supply?
     
  3. AdrianN

    Active Member

    Apr 27, 2009
    97
    1
    Just connect the base of the second NPN transistor, through a resistor, to the collector of the first transistor. Each collector is an output, and they are out of phase.
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Or if you have extra NOT gates in the circuit you can use one to invert the signal.
     
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