Transistor

Discussion in 'General Electronics Chat' started by Soon, Jan 27, 2010.

  1. Soon

    Thread Starter New Member

    Jan 25, 2010
    10
    0
    Hi, i know that transistor act like a switch but how do can control voltage like i want 5v to the input when the transistor is on? Which is better NPN or PNP?
     
    Last edited: Jan 27, 2010
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You need to be more clear in your question.
     
  3. Mike33

    AAC Fanatic!

    Feb 4, 2005
    349
    25
    With more information on what you want to do, we can help you find the right way to do it. It sounds like you have 5 volts at the input of the transistor? You can scale that voltage to be at the correct level to 'turn on' your transistor switch. There are a few different ways to do this, by attenuating the input signal or biasing differently, and it depends on what the application is.
     
  4. radiohead

    Active Member

    May 28, 2009
    474
    31
    Try an LM7805 +5V regulator to get your 5V, or a 6.1V zener diode (when it's forward biased, it should be around 5V), or as a last resort, string a bunch of forward biased 1N4001 diodes together until you get your 5V.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If you just want a simple voltage regulator using a transistor and Zener diode, see the attached. It's not terribly accurate, nor efficient, but good enough for many purposes.
     
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