2W Regulated Power Supply

Discussion in 'The Projects Forum' started by washer, Jun 22, 2012.

What is the easiest/cheapest/fastest 2W supply design with a 277Vrms in and 3V3 out?

Poll closed Jun 29, 2012.
  1. Capacitive, Rectified, Regulated

    0 vote(s)
  2. Resistive, Rectified, Regulated

    0 vote(s)
  3. Linear Transformer, Rectified, Regulated

    0 vote(s)
  4. SMPS (Flyback?)

    0 vote(s)
  5. None of the above!

    0 vote(s)
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  1. washer

    Thread Starter New Member

    Nov 25, 2009
    Hi all,

    It's been a while since I've posted but I've been lurking around.

    I'm working on a 2W power supply with a 277Vrms (line-to-neutral) source and a 3.3Vdc output with a max current draw of around 200mA.

    Since our requirements are pretty meager requirements, I've been looking at a resistive or capacitive supply similar to the ones discussed in this <SNIP>. I simulated the rectified resistive supply in LTspice and found out (more from trial and error with load resistors than the equations in the note) that it can't support a load of more than 50mA. I've attached two pictures of my simulation with a 16Ω load failing the ckt, and a 70Ω load showing proper operation.

    I can follow the math in the note, but am a little confused as to which equations apply to which topologies and how I can find out what the capacity of the supply is.

    Can anyone help explain what is the bottle neck in this supply? Is there a way to pull 200mA from a resistive or capacitive supply? If not, what would be the next easiest/cheapest/fastest design?

    I haven't found many step down transformers that I could use for a linear supply, but maybe I haven't been searching well enough. I've also started to look into some Flyback and other SMPS designs, but was getting pretty confused and would really like to get a "good enough" design working while I try to learn about a more efficient SMPS design. If anyone has any advice/references for a SMPS, I'd love to hear that as well!

    So is there any way to pull 200mA from this type of cheap supply?

    Thanks for any help!
    Last edited by a moderator: Jun 22, 2012
  2. bertus


    Apr 5, 2008

    I am closing this thread as it violates AAC policy and/or safety issues.

    6. Restricted topics. The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

    • Any kind of over-unity devices and systems
    • Automotive modifications
    • Devices designed to electrocute or shock another person
    • LEDs to mains
    • Phone jammers
    • Rail guns and high-energy projectile devices
    • Transformer-less power supplies
    This comes from our Tos:
    Terms of Service

    Better look for linear powersuplies with a transformer or SMPS powersuplies.

    For SMPS you can look here: SMPS
    For linear powersupplies you can look here: Power supplies

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