Power dissapation?

Discussion in 'The Projects Forum' started by Porkchop, Feb 5, 2007.

  1. Porkchop

    Thread Starter Member

    Feb 5, 2007
    17
    0
    Hi guys nice forum :)

    Little question.

    I have a regulator and a bridge rectifier mounted on the same heatink.

    I have calculated the power dissipated in the regulator and from this i have found the minimum heat sink C/W which is fine.

    How do i calculate the rec power though ?

    There is 25V sec from the transformer going in. And with a max draw of 7A

    Also when i know the power dissipation of the rec how do i account for this in my heat sink thermal resistance calculation. Do i just add the to powers of the reg and rec together

    Making Q the total sum?

    Thanks :)
     
  2. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
    Hard to follow what you're saying with the abbreviations. Can you add the part numbers and a a pointer to the datasheets?
     
  3. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,590
    777
    power dissipation = voltage drop x current

    in case of bridge rectifier it is 2*0.6V x 7A = 8.4W
    You just add this number to the heat the regulator makes and recount the heatsink.
     
  4. Porkchop

    Thread Starter Member

    Feb 5, 2007
    17
    0
    Sorry. When i say Rec i mean rectifier

    When i said Sec i meant the secondary winding of the step down transformer supplying the low voltage AC to the rectifier.

    I just want to know how to work out the power dissipated in the rectifier first Please.
     
  5. Porkchop

    Thread Starter Member

    Feb 5, 2007
    17
    0
    Smashing thank you. I did get that result but i assumed it to be far to low tbh :rolleyes:

    Going off this it looks like i might be better having it on a seportat heat sink, i think i might actually be heating it up lol

    Thanks guys!
     
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