imsai 2

From: Dave Dameron <ddameron_at_earthlink.net>
Date: Tue Aug 17 18:22:39 1999

Hi Tony and all,
At 12:28 AM 8/18/99 +0100, you wrote:
>> Also, if using a packaged 'OEM' supply unit, one is spared the
>> onus of compliance with a bunch of Regulatory Agencies... UL, FCC,
>> CSA, ISO..... this is the reason a lot of products came with
>> 'brick' or 'wall-wart' power units... someone else has already
>
>It's just a pity that those wall-warts in general are _not_ safe in my
>opinion (to the extent that I generally replace them with homebrew PSUs).
>
>Most of them have no internal fusing or thermal fuses (at least in the
>UK).
>
In many cheap wall-warts, the primary wire is undersized and is the default
fuse link. Is is scramble wound without much/any added insulation between
the start of the winding and the rest of the coil, so it being the fuse is
pretty common.
This practice may be worse for wall-warts for charging NiCd's, where the
smaller wire size provides the current limiting, especially with one or
more shorted cells.
-Dave
Received on Tue Aug 17 1999 - 18:22:39 BST