This is an isolated DC-DC converter, used to produce the -9V supply
for  BNC and AUI (D15) connections. the part number implies that it's
a 5V to 9V converter (this is almost universal), so I doubt it's
running from 12V (unless through a 5v regulator)

On Sat, 2 Nov 2002 23:14:38 -0600, you wrote:

>Hi all. So, in my PIC&Ethernet quest, I have aquired a bunch of NE2000
>cards based on the RTL8019AS chip. Some of them clearly have no
>connection to the +12V pin on the ISA bus - a bonus as then all I need
>is +5V. I do have a few cards that the +12V line is connected to though.
>However, they go to a component that I can't identify. I tried chipdir
>and a google search, and although there were some matches, there was no
>ID of what it might be. The closest thing was a product table for
>transformers. Question is, why would a transformer need +12? Anyway, the
>part number seems to be CFUS0509-C. It's a 24 pin wide DIP, and it's a
>big tall block, not an IC.
>
>Any ideas? I know that figuring out what it is won't let me magically
>run the card on +5V, but it would make me feel better knowing why I
>can't :)
>
>Thanks,
>
>Josh
>--
>A common mistake that people make when trying to design something
>completely foolproof is to underestimate the ingenuity of complete
>fools.
>        -Douglas Adams

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