Power supplies, need load?

Discussion in 'General Electronics Chat' started by Nicholas, May 15, 2015.

  1. Nicholas

    Thread Starter AAC Fanatic!

    Mar 24, 2005
    Hi guys

    I have a general question. Let's say that I have a power supply like this one(see picture).
    It's attached to a switch and a coil. The PSU is 40V, just to set a value.

    There is no load on the power supply except when the switch(or transistor) is flipped, and
    the coil fires(or lamp lights)

    Is this a bad thing? Would the PSU prefer to have load on it at all times? What can happen
    from the above mentioned use?

    Thanks a lot!


  2. Reloadron

    Well-Known Member

    Jan 15, 2015
    All depends on the power supply but generally speaking no, they do not require an external load. This is where the data sheet for the specific supply is nice to have.

  3. alfacliff

    Well-Known Member

    Dec 13, 2013
    some do require a minamum load. as stated before, check the data sheet. sometimes, a catalog like digikey or mouser has these power supplies, they will also have the data sheets.
  4. ian field

    AAC Fanatic!

    Oct 27, 2012
    The vast majority od SMPSU modules have bleed resistors on each output, just enough current to keep the PWM controller ticking over and stable.

    The real isue with switchers that get all the rails from one chopper transformer - often only one, or sometimes two of the rails are sensed for regulation purposes. If you don't draw significant current from the regulated rail, the PWM controller never gets off the starting blocks - the other rails just collapse as soon as you try to load them.