I don't know the card, but I do know the chip. It has two SPDIF-inputs, one
is at CMOS level, what means that the signal must use levels of about 5
Volt and 0 volt. The other input is supposed to have a sensitivity of 0.5
volt, which is enough for coaxial SPDIF. However, the threshold of this
input is still about 2,5 volt. So the coax signal should be biassed to
(centered on) this voltage, so that te levels are just above and below the
threshold.
I tried this with resistors and capacitors, but it did not work
satisfactory. So I made a simple amplifier to make CMOS levels, and this
works well, on both inputs.

CD-ROMs usually have a digital output on CMOS levels, so you can see if this
works.

If your card has a digital input for CD-ROM too, then this will probably be
the CMOS-level input.
Then you can try to create a coax input from the two-pin input. I would try
a transformer (2x ten turns on a ring core). The primary coil is the coax
input, the secondary goes with one end to a voltage divider (potmeter, about
10 K), the other one to the chip (one of the two pins). Put a capacitor of
about 10 nanofarad from the voltage divider to ground.

Maybe you will have a better advice from someone who knows this card, but
otherwise, you could try this...

Drivers is a problem. Or maybe, the problem is in the register. Anyway, you
should have an input switch on the mixer to switch to de digital input.
Disappearance of this button is a frequent and nasty problem!
Switching between the two inputs, and also switching the POLARITY of the
inputs (gives horrible noise and distortion if wrong) shoul be on the mixer
too, under the 'advanced' button.

The chip supports 48 or 44.1 KHz, up to 24 bits. Nothing else! The number of
bits you can handle depends on the recording software.

Regards,
Michel
Gouda, Netherlands

----- Original Message -----
From: lefko8 <lefko@...>
To: <cmi833X@yahoogroups.com>
Sent: Tuesday, September 21, 2004 3:11 PM
Subject: [cmi833X] L-8738-C


> Just bought a card from computer geeks for $9.95 that has the spdif in
> as 2 pins on the board. This is an L shaped card. Unfortunately the
> documents and pin descriptions are not for this card. I tried to just
> hook up a coax cable and run a D7 into it. This did not work. I hear
> there is a difference between cmos SPDIF and audio SPDIF. I have a
> few questions here.
>
> Do I need to create a circuit to convert to CMOS SPDIF?
>
> Does anybody know what the jumpers do on this card?
>
> How do I get the driver installed that lets me control the SPDIF?
>
> I have an IWill mb with the digital option. When I use the driver I
> use for that I still get no SPDIF control. I assume I can record on
> the CD-IN since that is what those pins were originially for. But, it
> would be nice to have the driver that has the spdif on it.
>
> Also, can I get it to input at 48/24 and 44.1/24?
>
> Any answers to these questions would be appreciated
>
>
>
>
>
> --
>
> cmi833x list archive, files, settings and unsubscribe
> - http://groups.yahoo.com/group/cmi833X
>
> Xenomorph
> - http://xenomorph.net
> Tom Browne's site
> - http://www.tbrowne.demon.co.uk
> Duncan Martin's site (incl. SAQ!)
> - http://www.codebunny.org
> Cmedia
> - http://www.cmedia.com.tw
>
>
> Yahoo! Groups Links
>
>
>
>