power plugs

Discussion in 'General Electronics Chat' started by vultac, Mar 9, 2009.

  1. vultac

    Thread Starter Active Member

    Mar 2, 2009
    Hi there, what is the difference if the ac to dc power supply pin head has got a center positive or center negative? thx
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    The direction of electron flow will be from negative to positive. Many components of many appliances will not work if current is backward. Some can be damaged by reversed current.
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    If the applied polarity is wrong and there is no protection device like a diode, then the circuit burns up. If this is in connection with that board that has the four regulators on it, you can get the data sheet for any of them.

    Using the data sheet as a guide and a meter to check, go from the unregulated voltage input pin of any regulator to the DC connector. Note which part of the connector is tied to the input, and you will see if it is center positive or negative.

    Center positive is the more likely arrangement.
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    One supply terminal is more correctly termed zero volts.

    The second terminal (the live or hot terminal ) is either positive or negative with respect to this zero.

    You don't actually have both positive and negative terminals on a supply, although they are often called this.

    On some equipment the zero terminal is also connected to ground or earth for safety reasons.

    When the zero terminal is grounded like this, safety is enhanced if the zero line is used as a shield or outer conductor.

    So the positive is normally the inner these days.
  5. Mike33

    AAC Fanatic!

    Feb 4, 2005
    UNLESS it's an audio device...things such as Boss pedals are set up for positive on the barrel, and Neg on the inner...they usually have a label there, though. Gotta watch that!!!