LED Dimmer - What should be used for Switching?


Closed Thread
Results 1 to 12 of 12

Hybrid View

  1. #1
    Join Date
    Nov 2003
    Location
    Greece
    Posts
    4,132


    Did you find this post helpful? Yes | No

    Default Re: LED Dimmer - What should be used for Switching?

    220x1,4=308Volt

    308-252=56Volt

    56volt*0.084mA=5Watts. This must be dissipated not on the mosfet only but on a resistor too. Otherwise LEDs may get overloaded.

    Not much, but not efficient either.

    Also there will be live part if this is of concern.

    Ioannis

  2. #2
    Join Date
    Jan 2006
    Location
    Istanbul
    Posts
    1,185


    Did you find this post helpful? Yes | No

    Default Re: LED Dimmer - What should be used for Switching?

    Quote Originally Posted by Ioannis View Post
    220x1,4=308Volt

    308-252=56Volt

    56volt*0.084mA=5Watts. This must be dissipated not on the mosfet only but on a resistor too. Otherwise LEDs may get overloaded.

    Not much, but not efficient either.

    Also there will be live part if this is of concern.

    Ioannis
    220VAC * 1.27 = 279.4 Volt DC

    279-252 = 27

    27 * 0.084 = 2.26 watts

    not bad with your approach.
    Last edited by sayzer; - 22nd September 2012 at 05:36.
    "If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte

  3. #3
    Join Date
    Nov 2003
    Location
    Greece
    Posts
    4,132


    Did you find this post helpful? Yes | No

    Default Re: LED Dimmer - What should be used for Switching?

    Sayzer, what is the 1.27?

    Ioannis

  4. #4
    Join Date
    Jan 2006
    Location
    Istanbul
    Posts
    1,185


    Did you find this post helpful? Yes | No

    Default Re: LED Dimmer - What should be used for Switching?

    I know what it is but not sure if I can explain it correctly.


    May be, Alain can give a hand here and explain it in technical and understandable terms.

    You considered 308VDC using full bridge rectifier (and elec-cap), right?
    Have you actually measured it?
    Last edited by sayzer; - 24th September 2012 at 16:47. Reason: added cap.
    "If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte

  5. #5
    Join Date
    Nov 2003
    Location
    Wellton, U.S.A.
    Posts
    5,924


    Did you find this post helpful? Yes | No

    Default Re: LED Dimmer - What should be used for Switching?

    Dave
    Always wear safety glasses while programming.

  6. #6
    Join Date
    Nov 2003
    Location
    Greece
    Posts
    4,132


    Did you find this post helpful? Yes | No

    Default Re: LED Dimmer - What should be used for Switching?

    So, I insist on sqr(2), meaning x1,41 of the rms voltage.

    Ioannis

  7. #7
    Join Date
    Jan 2006
    Location
    Istanbul
    Posts
    1,185


    Did you find this post helpful? Yes | No

    Default Re: LED Dimmer - What should be used for Switching?

    ok.

    First, we multiply AC voltage by 0.9.
    then, we multiply the result by 1.41.

    There, you have the result for DC voltage.

    In our case here,
    we muliply 220VAC by 0.9 = 198
    then we multiply 198 by 1.41 = 279VDC.

    This calculation is for full bridge rectifier with an elec-cap.
    "If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte

Members who have read this thread : 1

You do not have permission to view the list of names.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts