[mythtv-users] Driving a PAL tv using Intel graphics

Alex Butcher mythlist at assursys.co.uk
Tue Aug 23 11:08:26 UTC 2011

On Tue, 23 Aug 2011, Paul Gardiner wrote:

> On 23/08/2011 10:45, Alex Butcher wrote:
>> On Tue, 23 Aug 2011, Paul Gardiner wrote:
>>> On 22/08/2011 23:08, mlt at etruscott.co.uk wrote:
>>>> I have just updated my motherboard+cpu to a sandy bridge combo, which is
>>>> nice and quiet and low powered.
>>>> however, at present i still have a SD crt TV; at present i am using a
>>>> cheapo vga to s-video dongle thing that is pretty rubbish.
>>>> Does anyone know of a better way than this? I have a vga and dvi
>>>> connector so is there a solution that could use either of those? I had
>>>> wondered about the apple dvi-s-video connector does this work for linux
>>>> or is there a way of getting the graphics to drive a pal-tv directly?
>>> My first experiences of MythTV was use with an SD CRT. I was
>>> disappointed with the results until I discovered this:
>>> http://www.mythtv.org/wiki/RGB_Scart. No good to you if
>>> your TV doesn't have a SCART socket, but great if it does.
>> I'm a sometime contributor to that page, and I've been using Steve Hall's
>> 'Nvidia cable' it documents since 2006. Works really well, providing your
>> video card can output a 15.625kHz signal.
> Yes, that's what I used, plus an extra little circuit to hold the RGB
> signalling wire high.

I just used pin 9 of the VGA socket, through a resistor that, combined with
the 50 ohm impedance of the TV input would give the appropriate voltage. I
don't know how many TVs need it, though.

>> If you don't fancy building one yourself (I think all my parts, including a
>> case and some stripboard, cost about £15 from Maplin), Keene sell something
>> similar:
>> <http://www.keene.co.uk/electronic/keene-electronics/keene-sync-thingy-rgbhv-sync-transcoder/KST1.html>
> Coo. Nice. I don't think that existed when I built mine. I'd
> have gone for that.

I noted after I posted that the user questions say it was designed for a
Radeon, which suggests it may not be the same as Steve Hall's circuit after
all. It'd be a good, tidy base to hack from, though.

> Paul.

Best Regards,

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