Spehro Pefhany wrote:
On Mon, 10 Dec 2012 22:06:54 -0800, the renowned Robert Baer
wrote:

Jim Thompson wrote:
What's with wall warts? Do they have a five year warranty clock
built-in?

I just lost the third wall wart in a month.

All of them 5+ years old, or more, so I guess I can't complain.

What's to wear out... capacitors?

This one was for my Cisco BEFSR81 Router. I think it's actually a lot
older than 5 years.

I'm presently up and running on a bench supply:-}

...Jim Thompson
The "old" style = = unregulated is symple, xfmr,2 diodes, cap with
the xfmr a little under-rated (for smallest size) and gets a bit warm.

Four diodes and a thermal fuse (the latter to meet safety
requirements). Getting warm has a lot to do with how low end the lams
are. Paying a few cents more buys more efficiency and meets those
standards.
* I have opened many unregulated wall warts,from el-cheapo to
top-of-the-line, and NEVER seen any thermal fuse, period.


Crappy design as they all put out more voltage AT FULL LOAD thantheir
"specification".

Not what I've seen. They put out the spec voltage at full load.
* I have NEVER seen an unregulated wall wart like that,ever.
And i have seen an un-countable number of them in (about) 40 years.
Now, even the el-cheapo regulated ones (eg: linear series pass) do
meet label specs.
Switchers are better yet.


9V nominal adapter.. open circuit 13.48V, full load 8.96V.


Xfmr heat slowly cooks the cheap cap to death.

Yup. Put another equal size cap in the product and you can let the one
in the adapter die.


Best regards,
Spehro Pefhany