How do I modify the final current equation so that...?

Discussion in 'General Electronics Chat' started by PG1995, Oct 30, 2011.

  1. PG1995

    Thread Starter Active Member

    Apr 15, 2011
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    5
    Hi

    Please have a look on the attachment. My main question is at the end. How do I modify the final current equation so that it adjusts for the discharging up to only 27V? Please help me. Thank you.

    The answer given is: 4.5 + 5/6 e^(-t/0.15) mA

    Regards
    PG
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    657
    The time constant is correct, but I can't figure out where that answer came from.
    The cap's initial voltage is 32V, and it discharges into 27V through 1.5kΩ. Therefore, the current at t(0)+ is (32-27)/1.5k. Armed with this knowledge, you should be able to write an equation that expresses the current as a function of time.
     
  3. edisonli

    New Member

    Oct 31, 2011
    1
    0
    tough question to me
     
  4. PG1995

    Thread Starter Active Member

    Apr 15, 2011
    753
    5
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    PG1995 likes this.
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