Electronic 220/12 v switch.Pwr can not be rectified!!??

Discussion in 'General Electronics Chat' started by foundit, Feb 7, 2012.

  1. foundit

    Thread Starter New Member

    Mar 9, 2008
    8
    0
    hi everybody, please tel me why I can not get a dc from an electronic step down adapter (that is used to light a halogen spot 50W).

    I used a bridge and a cap. but I got 0.4 volt dc why, should i use a fast diods instead??

    thanks for help
     
  2. RiJoRI

    Well-Known Member

    Aug 15, 2007
    536
    26
    Posting a schematic will help people here aid you.

    --Rich
     
  3. foundit

    Thread Starter New Member

    Mar 9, 2008
    8
    0
    thank you for the rpely,

    I'm late, the first time I used a digital multimeter that gave a false result, when I tried again and pluged an oscilloscope I found 10Khz very narow spikes that vary in amplitude by the 50Hz line frequency, so I used the same bridge and the same cap. but I tested it with an analogue multim. and get around 17 V (open circuit). a block of leds then connected to the rectified current without current limiting R, the leds illumnited with flickering intense light, using R, the flickers decreased but not disapeared Why, should I connect a small cap (0.1 to 1 uf) parallel to the electrolytic one? I wish I will have time to try again.


    I have no schematic, but it is a very simple circuit of a rectifier bridge and a filtring capacitor to feed a led block and maybe to charge a lead accum.

    I've got some photo of the oscilo. screen, but they are of low quality, may I have time to post it.

    Thank you forums.:rolleyes:
     
  4. K7GUH

    Member

    Jan 28, 2011
    191
    23
    When someone on AAC asks you for a schematic, it is perfectly OK to draw one by hand. Especially if it is simple. As we used to say in the olden days, one picture is worth ....
     
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