Magnet on a running SMPS?

Discussion in 'General Electronics Chat' started by EB255GTX, Nov 22, 2012.

  1. EB255GTX

    Thread Starter Active Member

    Apr 30, 2011
    Hey smart people,

    this one has been interesting me for a while as a thought experiment - what do you think happens if you were to place a permanent magnet onto the ferrite core of an SMPS choke/transformer while it's running?

    It's not a trick question, assume a standard SMPS not anything unusual, and assume a small magnet i.e. not something that will suck the iron out of your blood through your skin.... :)

    THis experiment can of course be tried in the real world, but if either nothing observable happens, or the SMPS destroys itself, that won't tell me what happened inside the ferrite!
  2. takao21203

    Distinguished Member

    Apr 28, 2012
    I would not recommend to get too much excited on this.

    If you use a really strong magnet, how will the coil be able to change flux?

    You can answer this question to yourself.
  3. Externet

    AAC Fanatic!

    Nov 29, 2005
    You would increase the chance of saturation of the transformer core. The magnet could vibrate, lose magnetism.
  4. JDT

    Well-Known Member

    Feb 12, 2009
    It would saturate at a lower current in one direction than the other. This effect is used in CRT line scan circuits. (Or was back in the days of CRTs)
  5. EB255GTX

    Thread Starter Active Member

    Apr 30, 2011
    Interesting! Would make for an odd B-H curve :)