Quote:
|
Originally Posted by oldeurope
Hi Jeffrey, I often read in your statements that you like black level at 0V.
Why?
Sync tips at 0V makes sense to me because of the easy modulator biasing.
|
No equipment should ever rely on black level at a particular fixed voltage. In the broadcast and professional worlds, black level should be at 0V. When switching between video sources this prevents sudden changes in black level which can be difficult for the clamps in downstream equipment. Except for some video routers, all video inputs have clamps or DC restorers.
I've split the supply from a wall wart on occasion. In one design I regulated the wall wart output to 12V and split it to +5V and -7V with a 5V regulator. In this configuration you need to make sure that the regulator always sources current - they can't sink current - and I have used a ballast resistor in at least one design. Professional audio usually needs at least +/-12V, often up to +/-18V, to allow +18dBm or more.