[mythtv-users] HDMI_SPDIF directly to reciever
peter at vanderwal.us
Thu Jul 3 08:10:26 UTC 2008
I suspect, that while technically the SPDIF is supposed to be -0.5 to
+0.5, most amplifiers probably work fine with 0V to 1-5V.
I actually shelled out the $10 for ASUS adapter (so I get both RCA and
Optical), but I don't recall it having any active components on it other
than the optical driver.
> I found this article on the wiki and I have a question.
>>Most MythTV systems these days are built using a motherboard with
>>audio and video. However, the SPDIF signal is unfit to be wired directly
>>a SPDIF compatible digital audio receiver. The reason is that the signal
>> is a TTL signal, while it should be a signal swinging between -0.5V and
>>+0.5V. This requires that a simple circuit be built, using some resistors
>>and a capacitor, but the signal can not be used to drive a long cable and
>>thus additional components like a 74HCT04 are needed to amplify this
>>to acceptable levels.
>>This article describes how you can build a SPDIF TOSlink transmitter
>>circuit, using just two components.
> I have an ASrock ALiveNF5-eSATA2+
> that says it it has an HDMI_SPDI header on the motherboard.
> I wired it up directly to a female RCA jack and connected it to the
> coaxial digital input on my receiver.
> This article implies what I did shouldn't work but it does.
> Do I have a weird motherboard and this probably won't work on other
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> mythtv-users at mythtv.org
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