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Mains voltage frequency amplifier?

  1. Jul 19, 2010 #1
    hello all
    i wanted to make a circuit that takes power from the main a.c supply and increases its frequency( from 60 or 50Hz to about any frequency (lets say about 150KHz? or 15KHz?)), but the output voltage should not drop less than about 25 or 30v....
     
  2. jcsd
  3. Jul 19, 2010 #2

    berkeman

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    Staff: Mentor

    Sounds like you need to rectify to DC, and then chop back to AC... What is the application for such high voltage at 15kHz-150kHz?
     
  4. Jul 20, 2010 #3
    well i actually wanted to wirelessly through induction...incresing the frequency should help.....i dont understand how the conversion u mentioned would help though...
     
  5. Jul 20, 2010 #4

    berkeman

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    Do you mean that you want to transfer power wirelessly through induction, and to increase the transfer efficiency, you want the frequency of the AC power to be in the kHz range, instead of the standard 50/60 Hz of the AC Mains supply?

    There is no physical way to just increase the frequency of an AC power signal. You must instead make the higher-frequency waveform with a powered circuit. That circuit can get its input power from the AC Mains. It will usually rectify the input AC Mains into a DC voltage, and use that DC voltage to power the kHz oscillator and power amplifier to make your output power kHz AC waveform.
     
  6. Jul 20, 2010 #5

    mgb_phys

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    Would the easiest way be to use a 100V PA style amplifier ?
    Then you can play with the frequency easily.
     
  7. Jul 20, 2010 #6
    One of the applications in the old Sinclair Z30 / Z50 power amp applications and service manual was for a high power variable frequency oscillator for doing exactly this. I think the Z50 could reach 30 Watts.

    However one problem with this approach is that you need a transformer to step up the voltage if you are using semiconductor amps. You could get old valve amps to reach mains voltages this way though.
     
  8. Jul 21, 2010 #7
    @berkeman
    thats a good idea
    @mgb phys
    i dont think i have acces to that amplifier
    @studiot
    thats a good idea too
    @all
    thanks for ur replies and would a colpitts oscillator do the trick?
     
  9. Jul 21, 2010 #8
    You are looking for an audio frequency oscillator. You would have trouble finding inductors for the power levels you require.

    Traditional audio oscillator topologies such as Wein bridge or Phase shift or T would be better.

    The Sinclair circuit used their amp in a Wein bridge.
     
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