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design for homemade toroidal transformer

Discussion in 'General Electronics Discussion' started by tilup367, Oct 16, 2014.

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  1. tilup367

    tilup367

    13
    1
    Mar 3, 2014
    Hello,
    i have try to complete an homemade transformer, but it doesn't work. I think the problem comes from the toroidal core. I made it from a 9 3/4 inch. outside diameter x 2 inch. height X 4 3/4 inch inside diameter low-carbon steel shaft. When i look to the resistance with the multimeter on the primary coil i got 0.6 ohm. the primary coil has 159 turns of 14 awg emaled copper wire and the secondary of 33 turns of 14 awg. So, why it doesn't works? Not enough turns? Or i should made the toroidal core with sheet metal (low-carbon steel) laminate? Or something else i didn't get? (design for 120V AC input). Thanks to help me to illucidate this.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
    2,809
    Jan 21, 2010
    If you're using a steel core you need to laminate it to reduce eddy currents.

    What happens when you connect it? (smoke?)
     
  3. tilup367

    tilup367

    13
    1
    Mar 3, 2014
    after 1 or 2 seconds the breaker open (15 amps ac max) . So, if i understand well, sheet steel in circle laminate will work? To improve my general knowledge : what is eddy currents? thank you (*steve*) for your help
     
  4. tilup367

    tilup367

    13
    1
    Mar 3, 2014
    and what thickness will be "best" for the steel sheet? Any?
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
    2,809
    Jan 21, 2010
    I think most laminated cores have laminations about (or just under) 1mm in thickness. It's been a long time since I pulled a mains transformer apart and I've never unwound a toroidal mains transformer, so take my advice with caution.
     
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