Date   : Tue, 30 Aug 2011 20:46:54 +1000
From   : awilliams@... (Alan Williams)
Subject: eBay... sigh

Yes, ok my post was a bit ill considered in the cold light of day.

My main point, which I forgot to actually make, was that I would stay away
from ATX power supplies because of the added complication of working out
how to turn them on from the low voltage side.

I know this isn't much of a problem for somebody in the know but its not
as simple of snipping the wires of an old Beeb supply, stripping them back
and putting them under the screw terminals of something like one of the meanwell
offerings.

I checked again NET-35A has +5v/+12V/-5V as required but I didn't check if
it would fit in the space - my apologies about that.  I also agree one with
more current would be better, probably with old 5.25 discs more current on
the 12v rail too.

Alan

-----Original Message-----
From: bbc-micro-bounces+awilliams=linkme.com.au@... [mailto:bbc-micro-bounces+awilliams=linkme.com.au
at lists.cloud9.co.uk] On Behalf Of Pete Turnbull
Sent: Tuesday, 30 August 2011 6:02 PM
To: bbc-micro@...
Subject: Re: [BBC-Micro] eBay... sigh

On 30/08/2011 03:37, Alan Williams wrote:
> I would check out meanwell, they have a huge range.
> 
> http://www.meanwell.com/search/net-35/default.htm
> 
> Something along these lines would be fine.

Except it won't fit, because it's too wide (99mm x 97mm x 36mm).  A Beeb
PSU just fits the space and is 170mm x 84mm x 55mm.  It's also a bit light
on the +5V capacity, at 3A rather than the BBC's 3.75A.

There are industry-standard sizes for small SMPSUs...  The NET35 is a standard
size too, just the wrong one.

On 30/08/2011 02:28, Mark Haysman wrote:
 > A good replacement would be an Astec LPT64:
 >
 > 5v - 8A
 > 12v - 2.5A
 > -5v - 1A

That will certainly fit, as Mark said.  It's part of a range of industry-standard
sized PSUs, at 127mm x 76.2mm x 42mm (6" x 3" 
footprint), and has plenty of capacity as Mark pointed out (though the Astec
data sheet says 5V at 7A, not 8A -- but still "amply sufficient"). 
There are many more of the same size and varying voltages/capacities by other
manufacturers, but Astec is a good bet.

Expect to pay ?20 - ?50 for a similar PSU.  For example, an Astec LPT22 for
?20 is about the same rating as the one Alan suggests (5V at 3A 12V at 1.5A
but it has -12V instead of -5V); an LPT64 is about ?40.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York

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