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: Voltage Regulator Waveform

  1. Aug 28, 2014 #1
    I am doing a homework problem for my Power Electronics class. I have attached the relevant image. My question is, (referring to the TOP plot) why is the voltage regulator waveform (purple curve) identical to the voltage waveform coming from the diode bridge (green curve)? Shouldn't it be the inverse? My understanding was that when you add the voltage regulator waveform and the waveform that isn't constant (which would be the green curve in this case) you will get a constant voltage (red curve). However, the way it is shown, it would seem like you have to subtract them. Why is this??

    Attached Files:

    • q1.jpg
      File size:
      29.9 KB
  2. jcsd
  3. Aug 28, 2014 #2


    User Avatar

    Staff: Mentor

    Purple = Green - Red.

    The purple waveform is the voltage drop across the BJT. The output voltage (12V) is the input voltage to the BJT minus the voltage drop across the BJT.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted