RGB to sync on green

From: Malcolm Reeves (mreeves_at_fullcircuit.com)
Date: 02/04/05 

Date: Fri, 04 Feb 2005 15:53:33 +0000

Hi,

I'm looking at various new TVs etc. and it seems like the TV will take
component/RGB and the DVR etc can output RGB (component on some but
not all). However, scart rgb uses the composite for the sync and the
TV expects sync on green. So I can either buy a hugely expensive
converter or knock my own up.

So I think all I need is a LM1881 to get the sync from the composite.
Since the LM1881 is high input impedance and I'm not using the
composite then a lash up should not feed back significant noise to the
RGB lines. The LM1881 sync output is rail so it could be 5 or 12V. I
only need 0.3V so a 1K2 or 3K for 12V from sync output to G should
give me the right sync. The high impedance will attenuate any noise
on signal as well as not disturbing the impedance.

Sounds too simple - am I missing something? 

-- 
Malcolm
 Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
 (mreeves@fullcircuit.com, mreeves@fullcircuit.co.uk or mreeves@iee.org).
 Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
 electronics. More details plus freeware, Win95/98 DUN and Pspice tips, see:
 http://www.fullcircuit.com      or    http://www.fullcircuit.co.uk
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