1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help I Have An Electronics Test

  1. May 15, 2008 #1
    After studying amplifiers and their operation, i suddenly realised today that i dont really know how they work at all.

    Assume Vcc = 6V for an NPN transistor, biased correctly to fluctuate about 3V

    In the Vout, once the DC part has been removed, how can the voltage possibly go lower than 0. If the amplifier is earthed, then isnt the minimal possible voltage 0? Wouldn't the V out at this point then be clipped and become 0? From the questions ive seen it obviously isnt but i dont understand why...Please help
  2. jcsd
  3. May 15, 2008 #2
    If the output voltage of the transistor is greater than 3V the capacitor will charge. If the output voltage goes below 3V the capacitor will discharge and act like a voltage source itself, with its positive side on the left and the negative side on the right.
  4. May 16, 2008 #3
    Okay, that makes sense. So the capacitor acts as a voltage source and this is the reason why the voltage can drop below 0 (the Earth V)?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook