about the power supply

Discussion in 'General Electronics Chat' started by connie, Apr 10, 2009.

  1. connie

    Thread Starter New Member

    Mar 27, 2009
    I would like to ask what is the basic woriking principle of a power supply.

    Thanks for your help!:)
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    In general, to supply a stable voltage or current to a varying load. Sometimes the supply uses rectified AC as a source.

    In a linear supply, the pass element varies its resistance to maintain the stable voltage. In a switcher, conduction through a transformer is controlled to hold the output voltage/s stable. DC to DC converters use several methods to boost or lower the output relative to the input voltage.
  3. PRS

    Well-Known Member

    Aug 24, 2008
    Hi Connie! The question you ask seems to imply you are a newcomer to the world of electronics. I sure don't mean to insult you if you are not.

    There are two types of current -- AC, alternating current, and DC, direct current. The difference is that AC current flows back and forth periodically, and DC flows only one way always.

    An AC power supply is simply the AC voltage coming out of your home's recepticles. If you need a different voltage -- usually smaller -- then you use a transformer to reduce it to the desired value.

    But if you need DC, then that AC voltage needs to be rectified and usually reduced to a fraction of the power company's 120 volt supply. So you use a transformer to reduce the voltage then you use electronic devices called diodes (which pass current in only one direction) to create the dc voltage needed.

    The latter case gets more complicated. More if you want. ;)