Many years ago I worked for a company which make a device
called a Lock-In Amplifier for laboratory measurements. We
had designed special shipping boxes with multiple folded cardboard
pieces which fit into the box around the unit and acted like springs
to absorb jolts.  This was before industry got into using foam-in-place
packing foam and the like.

These packages worked really well most of the time.  One day we
got a unit which was returned for calibration. It had fallen off of a
loading dock or something and landed directly on the end against
which was positioned the front panel. The springs did their job and
the panel would have been fine EXCEPT that the power transformer
mounted in the center rear panel tore loose from its bolts and flew
forward.  It went through 4 circuit boards and came out through the
big analog meter in the center of the front panel.

The unit was a write-off.
The transformer mounting was redesigned, as was the packaging..
Never happened again, AFAIK.

RJG
>
> ----- Original Message -----
> From: "Dave VanHorn" <dvanhorn@dvanhorn.org>
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>;
> "Microcontroller discussion list - Public." <piclist@mit.edu>
> Sent: Friday, May 13, 2005 9:49 AM
> Subject: Re: [EE] Will phone charger work as a 5v DC power supply?
>
>
> > At 08:38 AM 5/13/2005, Spehro Pefhany wrote:
> > >At 07:17 AM 5/13/2005 -0400, you wrote:
> > >
> > >>Of course none of this should be a rule.  There are always unique
> tradeoffs
> > >>for every product.  A good case for a wall wart with a switcher is
when
> you
> > >>need enough power so that a transformer directly from the AC line
would
> be
> > >>too large, or universal input power is important.
> > >
> > >If the product is going to be shipped long distances by air, the weight
> > >saving from using a SMPS adapter should be taken into account. The cost
> > >savings can be in the dollars per kg range.
> >
> > We are starting to see switchers in wall-warts at wal-mart, which
> > means that it's cheaper to design in a switcher than to ship the iron.
> >
> >
> > >  Even if that's not important,
> > >the packing and overall size (cost of sea shipments of electronic goods
> are
> > >usually determined by the volume, not weight) can be much less if there
> isn't
> > >a heavy battering ram packed in each box.
> >
> > That is a factor too, and yes, the power pack can act as a hammer if
> > it breaks loose.
> > I have been known to check packing by tossing a packed box of product
> > off the third floor ledge, and then inspect every unit for damage and
> > effect on packing materials.
> >
> >
> > --
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