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Something wrong, help need! : making -8V and 5V PS,

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  • Something wrong, help need! : making -8V and 5V PS,

    Something wrong, help need! : making -8V and 5V PS,

    Hello guys..
    i am now making this 12VDC input, 5V and -8V output PS. (only building power suply, not


    but, mine doesn't produce -8V.
    but it produce -1V.. please, check this and tell me weather i got wrong components or wrong


    here is what i got and what it says on the surface. Mostly i got from and including their part number and link

    No. Fron schematic Actual component shows(on face shows) Part No.
    1. 555 timer IC, XRL555 (L555CP 9309) 34930
    2. 7805 5V reg IC, 7805T (L7805CV) 51262
    3. 220 uF cap CAP, Radial, 220uf 25V, 105C 158262
    4. 1K resistor Resistor, 1/4W 5%, 1.0K Ohm
    5. 3.3K resistor Resistor, 1/4W 5%, 3.3K Ohm
    6. Diode 1N4002 Diode, Sil Rec, 1N4002, 1A, 76961

    And, following are from local electronic shop.
    7. 7908 -8 Reg (7908 UC8352)
    8. 0.047 uF cap (A E 473)

    Let's assume that i wired all correctly.. (that's why it produce -1V rirhg?)

    here is some clue that i don't know.

    1. for diod, it looks like this, ====||
    and i matchiwired them as this,
    let me know whether i did opposite way or not

    2. Every compnent seems correct but 0.047uf Cap seems wrong or, maybe right..
    If it says A E 473, then is that right?
    also, schematic shows |( <----- like that, but it seems there is no + or - on it..

    3. Probably my timer is wrong???

    Please check the this and advise me why i am getting -1V not -8V..

    thank you
    <A HREF="" TARGET=_blank></A>

  • #2
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