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Re: [Amps] Series PC Power Supplies

Subject: Re: [Amps] Series PC Power Supplies
From: "Will Matney" <>
Date: Thu, 01 Jun 2006 15:07:56 -0400
List-post: <>
Another recommended practice is to place rectifiers across the + and - of each 
supply to try and balance the load. If the load is not balanced across each, 
one supply can be overburdened if just slightly off from the others. The 
rectifiers need to be rated at the same current capability of the total supply 
in a series connection. The low side supplies ground will be the supply ground 
and the ground for the last rectifier in the string. This is shown in several 
power supply books that mentions seriesing and paralelling supplies for 
increased voltage or current. Generally though, this practice of using several 
supplies is not really recommended because of the balancing problems.



*********** REPLY SEPARATOR  ***********

On 6/1/06 at 11:57 AM Joe Isabella wrote:

>Two things...
>1. You can get a brand new 25A switching supply for $80-90 if you look
>around.  I bought my Samlex 25A for $80.
>2. How did you series the supplies you have?  The "first" one will provide
>your "ground" connection.  Take the red wires from that and connect them
>to the black wires of the "second" supply.  Now take the red wires from
>that one, and connect them to the black wires of the "third" supply, which
>will provide the positive (15 VDC from the black wires of the "first"
>supply to the red wires of the "third" supply, in this case) to your rig. 
>Make sure you tied the orange wires to each supply's red wires so they all
>see "power good" line properly.  Make sure you have isolated the black
>leads from chassis ground on the second & third supplies as as the article
>says since they need to be floating (otherwise, the 5V from the first &
>second supplies will be going straight to ground).  If you didn't isolate
>them, you'll only see the 5V from the "third" supply...
>Joe, N3JI
>----- Original Message ----
>From: aborg <>
>To: Amps Amps <>
>Sent: Thursday, June 1, 2006 9:09:38 AM
>Subject: [Amps] Series PC Power Supplies
>Hello Amp'ers,
>Quick technical question. I'm embarrassed that I
>can't figure this out, but not quite a super tech yet.
>Here it is. I am attempting to series 3 pc pwr
>supplies. I can't seemed figure why I'm only seeing 5+
>volts. The link to the article is below. Here is an
>excerpt from the article. "Our second means of
>utilizing this low cost power is to connect the +5 VDC
>outputs of three separate supplies together in series.
>This will provide you with +15 VDC at 25 amps on up to
>the maximum rating of the supplies you have acquired."
>Can someone be kind enough to relieve from my
>embarassment ?
>Do You Yahoo!?
>Tired of spam?  Yahoo! Mail has the best spam protection around 
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