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7912 Voltage Regulator problem

Discussion in 'General Electronics Discussion' started by tonysnail, Nov 29, 2012.

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  1. tonysnail

    tonysnail

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    Nov 29, 2012
    Hi,

    I'm trying to build a -12V power supply from an AC Wall Wart.. The particular circuit I'm struggling with is the 7912 part of this power supply -
    HTML:
    http://www.musicfromouterspace.com/analogsynth_new/WALLWARTSUPPLY/WALLWARTSUPPLY.php

    This is what I built on a breadboard -
    [​IMG]
    http://imageshack.us/photo/my-images/842/7912circuit.jpg/

    To clarify - C1 and C2 are 3300uF caps, and the diodes are N4004s.


    I'm expecting -12V when I probe the blue wire with my multimeter (with the negative lead on the ground line at the bottom of the multimeter)..

    Unfortunately I'm not getting any voltage at all at the end of the circuit. In fact, i'm only getting 0.24V at the anode of D1..

    Could someone explain what I'm doing wrong? I'm trying to build an op amp power, and it's frustrating to be stumped by the power supply!

    Best wishes,

    Carl
     
    Last edited: Nov 29, 2012
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