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William Chops Westfield wrote:
> A lot of the inexpensive ethernet cards I've seen have "clever" PCB designs
> that allow the same PCB to be used for different transceiever options
> depending one which components are populated (ie if FULLY populated, they
> do AUI, 10base2, and 10baseT all on one card.)  They might also allow for
> the 9V converter to be run from either 5V or 12V inputs, depending on
> availability/etc.

That might make sense. This card has external connectors for 10base2 and
10baseT. AUI is brought out to a 16 pin IDC header on the card. I do
have another card with a 12V - 9V converter. While the converter that's
on this one is large, it doesn't have all the pins. In fact, it is
lacking most of them. I could understand if there was another converter
that plopped in instead of the 5V-9V.

>
>     And, if I don't plan on using coax, can I just forget about the 12V
>     supply?
>
> I *think* so.  I've not actually designed a PC ethernet card...

Interesting...

>     I guess the only real way to find out is to build my circuit
>     with only 5V, get it working on the card I have that I know doesn't
>     use 12V, then try it with one of these other cards.
>
> Well, you COULD find the actual datasheet(s) for all the components...

Well, I have done websearches on the remaining components. Some I
couldn't find datasheets on, but I think I have identified at least
their types. In addition to the RTL8019AS chip and the convertor, there
is the MTD392 coax driver and two things I believe I have identified as
transformers. Oh, and a 93LC46 for configuration info. So...nothing I
can figure out that needs 12V...

Thanks,

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
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