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From: Al Dykes on 9 Apr 2010 11:01

I don't have a high opinion of an external USB disk powered by a
wall-wart as industrial-strength kit. Having the PC powered on a UPS
and the Wall wart on house power has potential problems, IMO.

What are the thoughts of putting retail external USB disks on
entry-level UPS systems? These systems are stepped-sine power and
they don't specify switch-over time.

??


--
Al Dykes
News is something someone wants to suppress, everything else is advertising.
- Lord Northcliffe, publisher of the Daily Mail

From: Yousuf Khan on 9 Apr 2010 11:24
Al Dykes wrote:
> I don't have a high opinion of an external USB disk powered by a
> wall-wart as industrial-strength kit. Having the PC powered on a UPS
> and the Wall wart on house power has potential problems, IMO.
>
> What are the thoughts of putting retail external USB disks on
> entry-level UPS systems? These systems are stepped-sine power and
> they don't specify switch-over time.

I've always found UPS's have a life of less than 3 years.

Yousuf Khan
From: Arno on 9 Apr 2010 12:10
Al Dykes <adykes(a)panix.com> wrote:

> I don't have a high opinion of an external USB disk powered by a
> wall-wart as industrial-strength kit. Having the PC powered on a UPS
> and the Wall wart on house power has potential problems, IMO.

The wall-type PSUs are electrically insulated, there should not
be a problem, except perhaps aestetically.

> What are the thoughts of putting retail external USB disks on
> entry-level UPS systems? These systems are stepped-sine power and
> they don't specify switch-over time.

To what end? It should work, but it only makes sense if you
have the PC on an UPS as well. Also take care to use the
VA rating (V * A as stated on the plug), as switching power
plugs may not have power factor correction.

Personally I have my external USB disks on the PCs
12V power rail, but that takes decoupling (I use
a pair of STPS 3045 for that) and dampening (0.2R or
so, but a 4A fast-acting fuse also dampens enough
for two disks).

Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno(a)wagner.name
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
From: Al Dykes on 9 Apr 2010 12:17
In article <8291rtFlahU1(a)mid.individual.net>, Arno <me(a)privacy.net> wrote:
>Al Dykes <adykes(a)panix.com> wrote:
>
>> I don't have a high opinion of an external USB disk powered by a
>> wall-wart as industrial-strength kit. Having the PC powered on a UPS
>> and the Wall wart on house power has potential problems, IMO.
>
>The wall-type PSUs are electrically insulated, there should not
>be a problem, except perhaps aestetically.

They are also made by the lowest bidder. Of course, plugging one into
a UPS doesn't change that.

>
>> What are the thoughts of putting retail external USB disks on
>> entry-level UPS systems? These systems are stepped-sine power and
>> they don't specify switch-over time.
>
>To what end? It should work, but it only makes sense if you
>have the PC on an UPS as well. Also take care to use the
>VA rating (V * A as stated on the plug), as switching power
>plugs may not have power factor correction.


Voltage differentials, ground loops?

--
Al Dykes
News is something someone wants to suppress, everything else is advertising.
- Lord Northcliffe, publisher of the Daily Mail

From: Rod Speed on 9 Apr 2010 13:50
Al Dykes wrote:

> I don't have a high opinion of an external USB disk powered by a
> wall-wart as industrial-strength kit. Having the PC powered on a UPS
> and the Wall wart on house power has potential problems, IMO.

> What are the thoughts of putting retail external USB disks on
> entry-level UPS systems? These systems are stepped-sine power

Thats irrelevant. They all rectify the mains, none use the mains directly.

> and they don't specify switch-over time.

I prefer always on/continuous UPSs myself.

They dont necessarily cost anymore now.


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