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Ferrite magnet as toroid transformer

  1. Apr 30, 2012 #1
    Dear Experts

    I have a 1.5 cm ring magnet, you know, the black color type of common low magnetic power magnet.

    I wrapped 5 turns of copper wire around it on one side and then wrapped 10 rounds of another copper wire around it . I connected 5v battery to the 2 ends of the primary coil which is the 5 turn winding.

    I then measured with volt meter the secondary coil. I did not see the output voltage at the secondary coil increase.

    This is my noobie attempt. Please comment what could be wrong.

    Can a ferrite magnet be used to step up voltage?

    I want to step up the voltage by around 2 volts.

    Many Thanks.

  2. jcsd
  3. Apr 30, 2012 #2


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    Science Advisor

    Transformers only work on AC signals, so you would have to switch your battery current on and off through the primary winding to see anything on the secondary.

    However, a ferrite magnet would be a poor choice for a transformer core. Better options would be normal ferrite or soft iron laminations from a transformer.
  4. Apr 30, 2012 #3
    Are you talking about a toroidal "refrigerator" permanent magnet made of "hard" ferrite? You will need up to 300,000 amp-turns per meter. See attached table from http://www.what-are-magnets.com/10STRONTIUMCERAMIC.HTM

    Attached Files:

  5. May 2, 2012 #4
    Dear Experts
    So , what is the recommended way to stepup a 5v dc battery pack to 8volts, occupying minimal space? Kindly please offer me an idea.

    I have sen videos demonstrating how a joule thief can light up a 3v led using just 1.5v. I wonder can this toroid be modified/ used as-is to function as transformer ?

    Yes, i am using a toroidal fridge magnet.
    its ferrite but permanently magnetised, i think. Is the effect different than a non-magnetised ferrite?

  6. May 2, 2012 #5
    Use a boost converter, which are transformerless:http://www.linear.com/products/step-up_(boost)_regulators
    Other mfgrs also make similar chips.
    Magnets are not suitable for transformers.
  7. May 5, 2012 #6
    Thanks so much Bob S. I will get a ferrite toroid and try again.

    Cheers :)
  8. May 5, 2012 #7
    If you need to make a toroid transformer circuit, be sure to use a soft ferrite. I personally would search for a boost regulator circuit from Linear.com, using a DIP package. How many milliamps do you need? I have built ferrite transformer circuits before, and the boost regulators are easier.
  9. May 7, 2012 #8
    Dear Bob

    Thanks for your reply.

    I am looking at output of as high as 500 milliamps, input voltage of any between 9v to 12 v and output of 5.5 to 6v.

    Is it possible to get free samples of 1 or 2 units for testing?


  10. May 7, 2012 #9


    User Avatar
    Science Advisor

    You get free samples if someone thinks you might buy $500 worth of something. So, they ask who you work for and what your position is.

    So, unless you are likely to buy a lot of something, you shouldn't ask for free samples.

    Almost free, though, are these on Ebay:

    Synchronous rectification, Max efficiency up to 98%.
    Input: 4.75-24V.
    Output: 0.93V-18V ( Buck Mode, the input must be 2V higher than output ).
    Output Current: continuous 2.5A ( Peak 4A).
    Price about $3.50 US.

    Which country are you in?
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