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Powering a flyback transformer

Discussion in 'General Electronics Discussion' started by Timeless Trance, Feb 11, 2014.

  1. Timeless Trance

    Timeless Trance

    2
    0
    Feb 11, 2014
    Hello, this is going to the first project i've tried in a while. I came up with an idea on how to power a flyback transformer that dosent involve using mosfets or any components at all. My idea is to take apart an old amplified speaker and play the ouput of a high frequency sound file through them into the primary coil of the transformer. I just want some feedback if you guys think this might work.
     
    Last edited: Feb 11, 2014
  2. duke37

    duke37

    5,192
    706
    Jan 9, 2011
    Please tell us the objective of your project.
    Is a flyback transformer a TV line output transformer (LOPT)?
    What power is the speaker amplifier?
     
  3. Timeless Trance

    Timeless Trance

    2
    0
    Feb 11, 2014
    The flyback is from a tv and the speaker will be 9v. My goal is to make a hv dc power supply. The thought was to play a 15khz sawtooth wave through the speakers and maybe find a way to do audio modulation by chopping up the sawtooth wave at the frequency of the song.
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,264
    Nov 28, 2011
    You won't get much voltage out of it. The way flyback transformers are driven is:

    A component (transistor or MOSFET, usually) completes a circuit and allows current to flow from a DC supply into the primary winding. The current, and the magnetic field in the core, builds up according to the formula dI / dT = V / L. After a certain time (before the core saturates), the switching device is turned OFF. The magnetic field in the core starts to collapse and this generates a large "flyback" voltage on both the primary and the secondary. Load currents on the primary and/or secondary allow the magnetic field to dissipate. Then the switch is turned back ON and the cycle repeats.

    The large voltage generated by the flyback transformer is due to the sudden interruption of the primary current, which causes a "back EMF" in both windings. If the loading on the windings is small, this voltage is many times greater than the voltage that was applied to the primary. But both windings must be allowed to "fly back" in order for that high voltage to appear. Driving the primary from an audio amplifier will not allow this, because the amplifier has a low impedance at all times.
     
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