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Clueless Noob - A/C to DC switch

Discussion in 'General Electronics Discussion' started by Simon Robbie, Mar 31, 2016.

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  1. Simon Robbie

    Simon Robbie

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    Mar 31, 2016
    hi everyone!

    A thousand pardons for what I am sure is a silly question but I must ask!

    I want to buy / make a switch or box that can receive a 16volt 500ma A/C supply and convert it to 15volt 1amp D/C.

    Is it possible?
     
  2. davenn

    davenn Moderator

    13,784
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    Sep 5, 2009
    Hi there
    Welcome to EP

    in a word, NO
    in a few more words quoting Scotty from Star Trek

    "Ye canne break the laws of physics"

    that is ... you cannot get more power out than what you put in
    The best you could do, assuming 100% efficiency is 500mA
    The realistic estimate, accounting for losses in the circuit, is 300 - 400 mA


    Dave
     
  3. Minder

    Minder

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    Apr 24, 2015
    So you want to create a 15w supply from a 8w supply?
    M.
     
  4. Simon Robbie

    Simon Robbie

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    Mar 31, 2016
    Thanks for the concise reply.

    Essentially, I have a record player that runs on a 15v 1 amp DC power supply and I bought a unit that regulates the speed of a record player for switching between 33 and 45 rpm, but it turns out the speed regulator runs on a 16v 500ma AC supply in and out.

    The only other thing I can think of is switching the record players DC motor for the AC equivalent but the record player also has a DPS / transformer which I assume would need to be changed also?

    Thanks again.
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    is the deck and speed regulator two separate items ?
    if so can you not just run them each off their separate required supplies ?


    Dave
     
  6. Simon Robbie

    Simon Robbie

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    0
    Mar 31, 2016
    Hi, yes but the speed regulator replaces the standard turntable power supply. i.e. The speed regulator has a 16v 500ma A/C in power supply and then runs a cable to the turntable at 16v A/C 190ma (max) I wanted to place something between the speed regulator and turntable that would take the 16v A/C 190ma out from from the regulator and convert it to 15v 1amp D/C in for the turntable.
     
  7. davenn

    davenn Moderator

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    Sep 5, 2009
    ok

    as I stated in my first post, that isn't going to happen ... you cannot create power out of nothing

    you therefore need a 16VAC supply that has a higher current rating. say around 1.5A so that there is enough current to supply both sections


    Dave
     
  8. Fredx-3gtvi

    Fredx-3gtvi

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    Mar 31, 2016
    no, you cant do it. You will need two separate power supplies. Trying to convert from ac to dc always incur losses, and you end up with less power coming out than going in, and power is P=V*I ie voltage times current. and there is ALWAYS less P coming out than going in.

    cheers
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    or a single higher current supply as I stated ;)
    makes life easier
     
  10. BobK

    BobK

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    Jan 5, 2010
    Replacing the power supply is not going to give you speed control. You need a special circuit and sensors for feedback to do that.

    Can you give us a link to the so called "speed controller?"

    Bob
     
  11. Alec_t

    Alec_t

    2,935
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    Jul 7, 2015
    What speed does the turntable run at as it is now? My guess is the turntable already has a built-in speed regulator. It might be possible to tap into that to give a choice of speeds.
     
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