wall warts

Discussion in 'The Projects Forum' started by brozizds, Mar 30, 2011.

  1. brozizds

    Thread Starter Active Member

    Aug 15, 2010
    Hi guys,
    I have a question on wall warts. I have a RS #AD-567, with an output voltage marked 9V 210mA Class 2 power supply but when I check the out voltage I'm getting 12.6V. Is there a way to bring the V's down to the level I need (9volt) or is this a major problem?
    Thanks Jim :confused: (NEWBIE)lol
  2. Wendy


    Mar 24, 2008
    Most wall warts are not regulated. If you load them with the rated load they will be approximately the voltage that is stated. So if you pull 210ma it will probably be around 9V.

    I don't generally buy Radio Shack, because I have better choices. These choices include much cheaper wall warts and more selection. Many of them are regulated.

    You can regulate your wall wart several ways. You can use a 9.1V zener, for example, or buy a three terminal regulator IC (radio shack sells those too).
    Last edited: Mar 30, 2011
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    Those critters are cheap because they have limited regulation. If you place a load that will pull over 100 ma on the wart, the voltage should come down close to the rated 9 volts.
  4. someonesdad

    Senior Member

    Jul 7, 2009
    For what it's worth, I measured some 12 V wall warts out of my cache over the weekend looking for one that would be suitable for a project. A PDF of the spreadsheet data is attached.

    A lesson from the measurements is that you can't judge a wall wart by its cover (gee, that's kinda catchy). The HP 2.5 A unit was a very nice unit with an IEC socket for a power cord; it probably was used for supplying power to a laptop. It was pretty nicely regulated. Note it gave the rated output voltage when loaded to rated current.

    The last wart was a grungy-looking no-name one, yet it performed as nicely as the HP one.

    Actually, my application is going to add a regulator, so the amount of regulation wasn't terribly important to me. I'll probably use either the HP or Canon wart.