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ppppenguin · 20th Mar 2006, 6:09 pm

Ideally this sort of circuitry is DC coupled but the wandering black level caused by AC coupling is harmless. A clamp or DC restorer in the monitor or modulator sorts out the black level. In most professional video circuits it's usual to use +ve and -ve power supplies. This makes it easy to use DC coupling and sit the black level at 0V. Industrial and domestic video circuits don't usually have a -ve supply and either end up AC coupled or with the black level above 0V. Neither of these points matters in these applications.

20th Mar 2006, 6:09 pm	#56
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: PC as a standard convertor Ideally this sort of circuitry is DC coupled but the wandering black level caused by AC coupling is harmless. A clamp or DC restorer in the monitor or modulator sorts out the black level. In most professional video circuits it's usual to use +ve and -ve power supplies. This makes it easy to use DC coupling and sit the black level at 0V. Industrial and domestic video circuits don't usually have a -ve supply and either end up AC coupled or with the black level above 0V. Neither of these points matters in these applications.