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5v, 9v, 12v secondary side Power supply Board

Discussion in 'Power Electronics' started by olamide, Jan 19, 2015.

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  1. olamide


    Nov 11, 2014
    Hi! everyone, please i need you to help me check my secondary side connections schematics am trying to build up... 5v, 9v and 12v power supply out. please let me know if my connections are not clearly stated... This is my first time making connections like this, i really need your help.

    Attached Files:

  2. ramussons


    Jun 10, 2014
    Hello Olamide,

    I find a lot of errors in the schematic, like:
    - the transformer secondaries are shorted.
    - the full wave rectifiers are being wired up as half wave rectifiers.
    - the schematic is incomplete
    - . . . .

    If you are trying to draw a schematic from an existing PCB, you will have to redo the job of tracing.

    Not wanting to discourage you, but if you do not have an electronics background, it is going to be a steep learning curve to design power supplies, and that too a Switching type.

    Can you give us some more info on what you plan to do and what is your background knowledge on electronics.
    olamide likes this.
  3. olamide


    Nov 11, 2014
    Final Jpeg.jpg
    Hi ramussons, thanks for your comment... My Aim is to make up a power supply that have an output voltage regulator
    of about 5, 9 ,12 volt.

    Base on my knowledge in Electronics, am an amateur. Have gone through Basic introduction on electronics all alone with no guardians, am just putting things in practice.

    I have here Full image of the schematics. The last image i posted was the secondary side of the schematic. i just update some component to my component library like Voltage Regulator L7805CV, LM7809AC, L7812CV and also a component of 'programmable shunt regulator (KA431)'. Then, the 3 switch mode power rectifier was representing those voltage regulators. Along side, A chopper transformer which I isolated from a board ('19v'chopper trans.)

    Then, I got the Mosfet 'IRF540' Drived by an integrated circuit 'UC3842AN'. Also, I added an optocoupler to regulate the secondary voltage... Am just working on what resistor value will be along also the capacitor and all other component present in the schematic.

    Please I really need your Opinion so that to know where am Right or wrong....
  4. ramussons


    Jun 10, 2014
    Sorry Olamide, I'm not an expert on SMPS design. There will be other members who can guide you, especially on the Transformer details.

    There should not be any need for Analog voltage regulators when you are designing a Switched Mode Supply Unit. The design of the transformer should take care of the required voltage(s).

    If your objective is to "Design and Fabricate" the power supply, then I'm in the same boat as you :mad::(

    If your intention is to get a power supply unit with these output voltages, I'd suggest your getting an ATX unit of a desktop computer that gives you the 5 and 12 volts with lots of current.
    Depending on the 9 Volts current requirement, you can use a Linear Regulator (7809....) or a 12 to 9 volt Dc-Dc switching convertor.
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