How to build a 12v supply... newbie needs help!

Discussion in 'The Projects Forum' started by kiwisteve, Apr 25, 2013.

  1. kiwisteve

    Thread Starter New Member

    Apr 25, 2013
    Hello. This is my first post and please assume I know very little about electronics, but I'm trying to learn.

    I need a power supply that can do the following:

    1. Take 12-24v DC input (from a car battery, military humvee, etc) and provide a stable 12v DC output.
    2. Take 120-240v AC (from mains supply) and provide a stable 12v DC output (same as above)
    3. The 12v output is supplying a load of 40W / approx 3.5A
    4. It would also be nice to have a 5V output as well to charge a cell phone.
    5. Also, I might decide to want to power an Arduino device later on, so I'm assuming I may also want 9V?

    Can anyone please suggest a schematic or a product that would be able to do this?

    Thank you so much!

  2. Snappo

    New Member

    Apr 23, 2013
    Thats quite a large current requirement for the 12V, what are your PCB manufacturing and placement capabilities? Is this meant to be a hobby project or something you intend to market?

    I would use something similar to this: However its not going to be easy to make if this is a hobby project.

    For the AC requirement, you obviously need a transformer which can bring the voltage downto the input range of the LTM4605. I'd probably get a tranformer with 2 input windings for 120V/240V, and then you could have an external switch to select whatever your mains supply is. For the 5V and 9V supply those are easy, and I'd just step down the switched 12V output using linear regulators for those depending on current requirements, but if its less than 1A you can use regular 7805/7809's.
    Last edited: Apr 26, 2013
  3. t06afre

    AAC Fanatic!

    May 11, 2009
    Get a switchmode type power supply. They will be able to handle your input voltage requirements. This type is very common and cheap. You will for sure find something that fits your need. Like 5 and 12 volt output. If I remember correct. The Arduino is fitted with a standard voltage regulator. So they should work fine with 12 volt. But check it out to be sure
  4. tignmeg

    New Member

    Oct 17, 2012
    Computer server power supplies often have that sort of wattage on the 12V. You can pick them up cheap on Ebay.

    Edit: Actually even normal computer power supplies can supply +40W on 12V wattage these days. Maybe you have one laying round somewhere?
    Here's how to convert them into a bench supply
    Last edited: Apr 26, 2013