12v power supply for multiple 320ma-500ma devices (8)

Discussion in 'The Projects Forum' started by subcollec, Nov 12, 2011.

  1. subcollec

    Thread Starter New Member

    Nov 12, 2011
    Hello everyone,

    I need help with an experiment that I might apply.

    I'm trying to DYI build a 12v power supply for multiple 320mA/500mA security cameras.

    I'm thinking about starting with this...


    ... since Radio Shack is down the street, it provides ±1.2~24VDC regulated at 1A.

    I'll be breaking out the +/- to eight separate +/- terminals to power the cameras.

    I need to know how to build that separation properly, safely, and efficiently. It can't be that I just connect all 8 negative leads to the negative post and all 8 positive leads to the positive post, can it?
  2. paulktreg

    Distinguished Member

    Jun 2, 2008
    If I'm reading this right you need to power up to eight cameras @ 500mA each so that's 4A, add a little extra headroom and I'd suggest a 12V power supply capable of 6A minimum. You can just simply connect all eight +ve and -ve leads to the power supply if you wish but one faulty camera could shut the power supply down and take the other cameras out. If you want a little extra safety you could install a 1A fuse in line with each camera +ve supply.
  3. SgtWookie


    Jul 17, 2007
    Hello subcollec,
    I suggest avoiding using that type of supply for something that's going to be on 24/7, as it won't be very efficient, and it's not robust enough to meet your requirements to start with.

    You have 8 cameras that each can draw up to 500mA apiece; 0.5A x 8 = 4 Amperes. You need at least a 20% safety margin, as you don't want to operate any electronics at 100% of its' rating. So, you need a 5A supply, as 4A/80% = 5A.

    MPJA has just what you need:
    A 12v, 5A regulated switching supply, for less than you'd pay for the kit.

    I've bought from them several times; they ship very quickly and their stuff is as advertised.
  4. bountyhunter

    Well-Known Member

    Sep 7, 2009
    Wow. 60W regulated supply for $18 complete.... it would cost 3X that much to build it. Now I remember why we never competed in the under 500W power supply market.... China's slave labor is too efficient to price below.