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  1. #1
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    12V power source without any IC.

    Hi All,
    I'm new to analog design. I need to design an 12V DC minimum 1 amp power source that takes input from 220V AC without using any ic component. I'm familiar with the transforming and rectifying. My only problem is I don't know how to design a steady voltage regulator. I'v looked up online but all of the designs uses ic components. Any research source and/or design examples will be appreciated.
    Thanks in advance.

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  2. #2
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    Re: 12V power source without any IC.

    I'm (barely) curious why you "need" to use inferior
    technology. If I had to guess, I'd guess this is a school
    project and somebody else gets to set the boundaries
    and criticize the BOM.

    Your easiest regulator will be a zener + (N) forward diode
    stack, followed by a Darlington NPN pair. You can find
    zeners in pretty fine-binned breakdown voltages. The
    tempco of a zener plus single forward diode is sorta-flat.
    You'd add a couple of diodes up to compensate the couple
    of diodes down, that the Darlington will impose. Your zener
    stack pilot current must include the Darlington base current
    at max output.

    The linear supply will get way hot, so plan on at least a
    big finned heat sink able to throw (VINmax-12V)*1A worth
    of power. Maybe a fan too.

    If you want good ideas for old timey analog designs, try
    the discretes databooks and applications volumes from
    RCA and Motorola semiconductor companies. You should
    be able to find these on archive.org. I remember seeing
    stuff like full designs (schematics and parts lists) for
    >100W Class AB audio amplifiers to demo their matched
    power bipolars and so on.

    You could go further (if the regulation requirements laid
    down by "whoever" demand it) and instead of an open
    loop reference stack and follower, add a poor-boy discrete
    error amplifier (op amp, made of discretes). This would
    help load rejection and temperature stability big time as
    reference stack Vf, and power NPN Vbe, are going to
    drift apart with applied load. You ought to be able to
    make a 4-6 transistor op amp, its offset voltage, speed,
    gain are liable to be inferior to ICs but still better than
    not trying at all.


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  3. #3
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    Re: 12V power source without any IC.

    here you go, this link contains schematics that will supply what you want ...

    http://www.semanticscholar.org/paper...a3f7069b314f29



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