"Electronic Transformer" ... as 12V PSU?

Hi all,
I need to replace a laptop style (12V 7A) PSU (not for a laptop) and was wondering if the sort of thing you can get to power 12V LED lights would be suitable?
I'm talking of this sort of thing:
https://www.toolstation.com/shop/Lighting/d220/LV+transformers/sd3306/Electronic+Transformer/p11098
Is it just a 12V SMPSU or is it summat 'different'?
I find it weird that they don't mention the output voltage in the blurb, just a range of wattages (it does say 11.4V on the item itself though).
Cheers, T i m
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It can't be very well regulated if it is dimmable. And it is probably quite noisy. So it very much depends on how well the item you are going to use it with can cope with that.
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Roger Hayter

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On Thu, 28 Dec 2017 23:11:35 +0000, snipped-for-privacy@hayter.org (Roger Hayter) wrote:
<snip> >> I need to replace a laptop style (12V 7A) PSU (not for a laptop) and

Yes, that got me wondering and hence why I asked here.

Ok.

Good point. It was just that the world is still 'weird' because of that Xmyth thing and Toolstation are just down the road, *if* it was just a std 12V SMPSU etc.
It's to power my home server that uses a fanless Atom board, 3 x 500G laptop drives and one of those low power PSU's that take a single input voltage and fit in the mobo power connector.
A mate gave me the 12V 7A laptop type PSU a good while back but I doubt it is a good one or able to maintain 7A. I might rig up a feed using my variable bench PSU and see what it actually draws worst-case and get something that can cope with that easily.
If I get one of those semi open frame type SMPSU's I could put it inside the PSU case as that only contains the one 120mm fan atm.
Cheers, T i m
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You have probably noticed that the purpose-made ones from the computer power supply companies are inordinately expensive. Some of these Atom boards will alternatively take a standard ATX PSU. Otherwise, for economy, I agree with your plan. But get a good quality one as it is a SPOF for your server, even if you have a UPS.
--

Roger Hayter

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On Fri, 29 Dec 2017 11:05:27 +0000, snipped-for-privacy@hayter.org (Roger Hayter) wrote:
<snip> >> A mate gave me the 12V 7A laptop type PSU a good while back but I

I have indeed. ;-(

Yes, this one was powered by such when I first built it but took it to the Pico ATX PSU when the conventional PSU fan got noisy (and a 400W PSU (needed to get a quiet / 120mm fan) was a bit of an overkill).
I think the Pico supply is 160W and I think it suggested a 15A (12V) PSU (if fully loaded etc).

Agreed ... that's why I was always a bit cautious about this 'cheap' PSU my mate gave me.
Cheers, T i m
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That's a *lot* of power for a fanless Atom based board. My full-blown desktop machine with a (6th gen, or maybe even 5th gen) I5 and three disk drives only consumes 18 watts when idle and maybe 25/30 watts when working hard. That's a maximum of around 3 amps at 12 volts.
I doubt very much if you need anything like 7 amps.
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A significant component is the starting current for the drives. If this is not specified then you really need an oscilloscope to check. Even laptop drives may draw twice their rated current when operating.
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Roger Hayter

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So stagger the startup. Most PSUs will handle short term surges more than their rated output anyway and/or the output will droop a bit as the drives spin up.
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If the output droops the CPU may reset or generate unrecoverable errors causing a reboot. Although the drives may stay running and therefore the process not be infinitely repeated, this is a bad idea which could cause data corruption or electronic harm of some sort e.g. to voltage regulators.
Staggering the drive start up is easier said then done unless the hardware is designed to do this.
--

Roger Hayter

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On Fri, 29 Dec 2017 15:05:37 +0000, snipped-for-privacy@hayter.org (Roger Hayter) wrote:
<snip> >If the output droops the CPU may reset or generate unrecoverable errors

Noted.

I think I may have seen a 'Spinup delay' on some Mobos (for std drives even) but I'm not sure if it is present on this one (and as it's offline I can't check either).
As I've not touched the server for ages I might pull it out in any case and put it on the bench and 1) check it over, 2) measure the current, 3) replace the fan in the PSU for one of these Arctic F12 'Silents' and 4) blow it out.
Technically, I should have retired it a while back when I built the WHS 2011 but whilst this old WHS V1 keeps going ... ;-)
Cheers, T i m
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Possibly, but not very likely as it's a 12 volt supply and the CPU etc. probably all run at 3.3 volts, that leaves *lots* of headroom for the 12 volts to dip a little without having any effect at all on the electronics.

True, it was only a possible idea.
I *still* think 12 volts 7 amps sounds a crazy amount of power for a fanless Atom board (even including some disk drives). It's something like three times as much power as my I5 desktop with four disk drives in takes.
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<snip> >I *still* think 12 volts 7 amps sounds a crazy amount of power for a

I've not suggested anything otherwise, just that my friend had a 7A PSU spare and I thought bigger might be better (considering it was made in the Far East, was 'cheap', felt 'light' and I wanted it to run cool rather than hot)?

And I wonder what capacity PSU you have in there? 450-500W possibly? ;-)
Cheers, T i m
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It has an 80 watt power supply. :-) For the good reason that a larger power supply would probably be horribly inefficient when running at 18 watts.
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Ah, ok. ;-)

Quite ('80 Plus' etc).
As I have said elsewhere, I think I'd be happy with a 'good' 5A PSU, allowing for a little overhead and happy if it wasn't running close to maximum design load just to get maximum efficiency etc.
But I still intend to measure it as if it really only draws what we think it might, I could get away with something even smaller (cheaper and easier to get). ;-)
Cheers, T i m
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On Fri, 29 Dec 2017 11:21:49 +0000, snipped-for-privacy@hayter.org (Roger Hayter) wrote:
<snip>

I remember my old NW 3.12 server and it had 5 SCSI drives and hearing them all spin up on boot. ;-)

These (x3) are Hitachi 500G SATA drives from about 5 years ago FWIW.
I think it's a Dual core Atom, no optical drive, 4G RAM in 2x2 and the Pico PSU just powers the mobo, drives and the 12V 120mm low power / slow fan in the std ATX PSU case.
I fitted the DC jack socket to the case just under the PSU (Mini tower case standing behind the lounge TV). The Topfield is normally connected to the server but doesn't add any extra load, as is a 3TB powered external backup drive.
Cheers, T i m
p.s. I've bought some Arctic F12 Silent fans and may swap the one out of the server to see if it could be quieter still (you can only hear that it's on after you turn it off). ;-)
The 3 x laptop drives are suspended from silicon bands. ;-)
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<snip> >> A mate gave me the 12V 7A laptop type PSU a good while back but I

Agreed ... and why I gave the 7A PSU a go, assuming it was only really good for 5 etc.

You may well be right and I think I'd be happy with a *quality* 5A PSU (or a cheaper 10A etc). ;-)
But, 'you can manage what you can measure' so I'll try it on my bench PSU first and 1) make sure everything is ok (Bench PSU is current limitable and goes up to 15A) and see what it actually draws on startup.
Cheers, T i m
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T i m wrote:

Distress purchase if you need one before the world gets back to normal, and can measure that 5A would suffice?
<http://maplin.co.uk/p/psu-n63jn
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wrote:

Hehe ..

;-)

Thanks for that Andy ... and could be a solution (even at that 'sea' price) if it's likely to be a 'good' / quality item?
It's like when you buy these replacement laptop PSUs and they weigh a fraction of the original. ;-(
Cheers, T i m
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On Friday, 29 December 2017 10:03:32 UTC, T i m wrote:

a lighting psu is totally utterly & completely unfit for that purpose
NT
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On Fri, 29 Dec 2017 05:54:38 -0800 (PST), snipped-for-privacy@gmail.com wrote:

Agreed.
Cheers, T i m
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