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How can l use caps to stepdown or reduce mains voltage

Discussion in 'General Electronics' started by kofi Mpengya, Jul 8, 2003.

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  1. kofi Mpengya

    kofi Mpengya Guest

    l quite remember when l was a kid l use to see no transformer but only
    caps in my oldman's battery charger. It was strong and reliable.Thus
    anyone know much about this technology? l will be pleased if he or she
    can share this with me Thanks .
    gsrilanka likes this.
  2. Robert Baer

    Robert Baer Guest

    Basically, the capacitor in series with the load aer an AC voltage
    Determine the AC impedance of the load, and then required dropping
    impedance of the capacitor, then the capacitance.
    Good for resistive or capacitive loads.
    Inductive loads cannot be calculated this way, as there is a
    "resonance" phenominum that will make voltage drops in excess of the
    line voltage.
  3. Craig

    Craig Guest

    The post above is correct re voltage dividers. It is not just cap as
    such (caps can increase voltage sometimes) but the way they are used

    Below is a site that explains voltage dividers without to much fuss.

    If this link fails go to
    tech info section and the article is in the introductory-beginner's

    Craig Ryder
  4. N. Thornton

    N. Thornton Guest


    I've used Cs to reduce V on L loads, and it works fine. Inductive
    loads are of course RL loads, not pure L. I've used it for reducing
    power on various motors, current controlling fl lights, and in light
    low cost PSUs. Works great!

    For your battery charger all you need do is size your cap to pass the
    required current at Vmains - Vbatt. But I really wouldnt do it...
    1. your battery and charger terminals will be live
    2. the V applied to a flat or full battery will be excessive.
    3. So you might die.

    Regards, NT
  5. JeffM

    JeffM Guest

    l quite remember when l was a kid l use to see no transformer but only
    Yup. Make out your will first.
    In Europe, they have outlawed these.
    shorted capacitor==death
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