Test Corrections

Discussion in 'Homework Help' started by super70elco, Feb 15, 2007.

  1. super70elco

    Thread Starter New Member

    Oct 30, 2006
    8
    0
    I took a test the other day and got a couple simple mistakes wrong but I cant seem to find the real answers on the web so I come here PLEADING to find some help....! I know these might be dumb questions but I cant find the answers to them any where.
    1. What component is used for regulation in a power supply?
    2. What does VCT mean in terms of power supplys?
    3. When you have a cap tied to ground what is the purpose of that?

    Please any help would be GREAT....! Thank you!
     
  2. Papabravo

    Expert

    Feb 24, 2006
    9,908
    1,723
    1) The wiseacre answer is a voltage regulator. Another possible answer might be a zener diode.
    2) VCT is an abbreviation for Volts Center Tapped. It refers to the configuration of a secondary output on a transformer. The center tap is a terminal on a transformer winding that is in the center of the winding. In a given application it may be used or unused.
    3) A capacitor to ground provides a low impedance path for high frequency noise. It also removes ripple, or filters, the output from a halfwave, fullwave, or bridge rectifier.
     
  3. super70elco

    Thread Starter New Member

    Oct 30, 2006
    8
    0
    :) Thank you very much....! You Saved me......!
     
  4. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,280
    1,072
    Forty years ago, one used a bleeder resistor to improve regulation, but somehow I don't think contemporary electronic designers would use such an inefficient method.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    9,908
    1,723
    And here I thought they were a safety feature to discharge large filter capacitors when the AC gets turned off. Nobody told me about improving regulation - frown!
     
  6. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,280
    1,072
    Yeah ... I always thought they were for safety too .... but that was one of those questions that typically caught people off guard. :)

    Design an old type power supply ... FWR ... pi filter ... and then place a 100 ohm bleeder. Look at the regulation for a changing load, say 1k and above ...

    I hated that question ... probably the primary reason it stuck with me after these many years ... :)
     
Loading...