universal voltage adapter(like cellphone charger)

Discussion in 'General Electronics Chat' started by ees1, Jan 29, 2008.

  1. ees1

    Thread Starter Active Member

    Jan 7, 2008
    37
    0
    hi, I am searching a schematic for cellphone universal voltage input(85V~264V) power adapter in internet, and I couldn't find any circuits for this.
    The small AC-DC cellphone ac adapter is extremly cheap in market, but it is so strange that there is no circuit schematic in internet.
    My understanding so far is that it should have some flyback circuit with no PFC or EMI filter because of low power. I just want to know a little bit more info for this circuit layout so i can implement the circuit for the project I am working on.
    Could anyone help providing the links or circuit simple follow chart? Many thanks
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Try a search on "ac dc converter schematic."
     
  3. ees1

    Thread Starter Active Member

    Jan 7, 2008
    37
    0
    Thank you for reply first of all. but this is not only AC/DC, but also universal voltage.
     
  4. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    Google "Switch Mode Power supplies".
    Basically the AC is rectified and then "Pulse Width Modulated" at a high frequency via a small step down/isolating transformer to the secondary voltage rectifier. The output is monitored and a feedback circuit controls the PWM to ensure a regulated output for a variety of loads and input voltages.
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Yes. That's why I suggested a converter. They provide constant o/p over a wide range of i/p.
     
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