AC Power limiter

Discussion in 'The Projects Forum' started by jwbrooks0, Nov 20, 2013.

  1. jwbrooks0

    Thread Starter New Member

    Nov 20, 2013

    I'm still new electronics so I apologize if my question is very basic. I would appreciate any feedback or links to relevant material.

    My question:
    I need a simple way to regulate/limit the power delivered to a system. I don't particularly care if I do this by limiting the voltage or amperage or both.

    The requirements:
    It cannot add substantial noise to the signal, and the waveform needs to stay intact. I would prefer to do this with minimal power loss.

    My ideas so far:
    1. My first idea was to use a variac. This would work, but it's not desirable long term because I'll likely be making several of these units. Variacs are also heavy and expensive. Maybe a more permanent transformer?

    2. Light dimmer. Reading more about these told me that they clip the AC wave to dim the light, and they add noise to the system.

    3. Maybe I could use a capacitor or inductor (choke) in series with the hot line. If I designed the capacitor or choke correctly, I could partially filter the 60Hz signal and therefore reduce the amplitude of the current to something I would prefer. I have no idea if this would work or how to go about designing it.

    4. .... No other ideas yet. If anyone can think of anything reasonable (not too expensive or involve lots and lots of components), please let me know.

    Thanks guys. If you have any ideas, suggestions, or references, please let me know!
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
    It might be better to tell us what your are trying to do. You covered a couple of the easier ways to do it but a dimmer for example might not work well with certain electronics.
  3. tcmtech

    Distinguished Member

    Nov 4, 2013
    I would look at a using a lighting ballast.

    They are for the most part a constant wattage output transformer.
  4. inwo

    Well-Known Member

    Nov 7, 2013
    That's the right idea.

    Need to know voltage and current requirments, and limits, to design a leakage reactance transformer.

    An example would be a neon sign transformer which limits current to 30 or 60 ma.
  5. wayneh


    Sep 9, 2010
    DLP TVs use a ballast power supply as well, to control current thru the bulb's filament.