smps power supply over low ohms

Discussion in 'General Electronics Chat' started by Guinness, Dec 11, 2010.

  1. Guinness

    Thread Starter Member

    Dec 31, 2009
    Hi, I know the title does not make much sense so let me explain.

    I am making a electromagnet for a project, I have wound the coil but it only measures 0.7 ohms on my multimeter. I have a shop bought 80W variable smps to power the coil with. It has voltage and current limiting settings which I can select.

    I am wondering if it would be ok connecting the power supply to the coil direct with no other components? or would that damage the power supply as the load is such low ohms it would be like shorting the live and neutral together?

    I dont know much about the internals of smps and am unsure if they are designed to handle such situations.

    Cheers in advance.
  2. bertus


    Apr 5, 2008

    Do you have more information on the powersupply? (brand, type, datasheet).
    What will be the application for the electromagnet?

  3. Guinness

    Thread Starter Member

    Dec 31, 2009
    Hi, yea I got the power supply from Maplin,

    This should be the link to the page if I done it right.

    Its being used for a geeky magnetic levitation device, the coil has a iron core and will be used to hold a permanent magnet in place.
  4. timrobbins

    Active Member

    Aug 29, 2009
    Yes the simple specs indicate it is happy to operate as current controlled output, no matter what the voltage. However, you need to have a good appreciation of what current the coil can operate with - with respect to coil power dissipation and to wire operating current density. If you had the 16V supply that can operate up to 5A, then you nominal max power dissipation is about 3.5W. I suggest you put a diode across the coil, to limit any high voltage spikes that could damage the power supply or other equipment - and that would mean marking the coils terminals for polarity.
    Guinness likes this.