Switch mode question

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Is it permissable to run a couple of  dc switch mode supplies in
parallel to gain extra current capacity ?
  What are the potential  problems
  Tnx
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Re: Switch mode question

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Generally no, unless they were designed for it.  But I figure you
suspected that already.

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Instability - two regulating "loops" fighting and one losing.

You *can* purchase units designed to operate as master/slave.  If you
don't already have some of those, it's crazy to go that route instead
of just buying one that's man enough to do the whole job.

Re: Switch mode question
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I suspected as much but finding one large enough is if possible very
expensive , might have to reconsider making another linear

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Re: Switch mode question
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What Voltage current are you looking for?

Mik

Re: Switch mode question
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48Vdc 1500 watts

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Re: Switch mode question

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Meanwell SMPS  ~$700 ea

RSP-1500-v, 1500W SMPS v = 5V, 12V, 15V, 24V, 27V, 48V...
70-110% V adj, alarm o/p, parallel up to 5400W, 12V aux.


http://users.tpg.com.au/users/p8king/s100.htm



Re: Switch mode question
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I have a large junk box , I have caps , sinks and transformer free , now
those switches  look like decent supplies but are way over my hobby
budget , if I can source suitable pass transistors for a 48cdv rail
building a regulator control board will be easy
  Thanks anyway , ebay offers 400 watts for under $100.00 delivered just
nothing large enough atm out of China

Re: Switch mode question

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Yeah, I just checked the price out of interest.

25 yrs ago you might have picked up an old Telecom rectifier good for a few
hundred amps.....



Re: Switch mode question
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I have two of the old telstra transformers here from when I started with
them about 30 + years ago  and the tranny from a 150 amp dc tig , just
sold my 3.5kw 48 vdc supply , I have a copy of switchmode power supplies
spice and p so when time permits might build one
There is a Honkers bloke who does 350 and 400 watt supplies very cheaply
, perhaps one of the blade server 48Vdc remote supplies will show up at
a fair price

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Re: Switch mode question

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You could link 4 ATX power supplies in series. You would have to open up 3
of them and cut the link between the negative terminal and earth.
It will be safe if you hard wire all 4 outputs together in series in a way
that they can not be disconnected. I think the only reason they earth the
negative output is so that it doesn't float at a high voltage WRT mains. So
if all your connections are good, the highest any output will float is 48V.

Modern ATX supplies typically have two 12V 20A rails. But many dont realise
that they are not actually separate rails. The rails are separately filtered
with caps, but come from a single SM transformer. (typically)

So each ATX supplies 12V at 40A. Cost is about $40 each from ebay, so $160
is your total.





Re: Switch mode question
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  I thought about it but  I need 48vdc @1500 watts , atx wont cut it but
I can get cheap Asian industrial supplies  @450watt each , will have to
check the schematic to see if it might work
  Ta
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Re: Switch mode question

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48V x 40A = 1920W



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