This is a simple circuit to connect your VGA graphics card to your TV. The advantage of using RGB over S-Video is superior contrast and clarity. The schematic of this circuit is taken from Tomi Engdahl’s site. The circuit basically XORs together your horizontal and vertical synchronization signals to create a composite sync output, and adjusts output for input polarity. By setting the resolution and timings on your VGA card correctly, it is possible to generate a signal that the TV will accept. This circuit works for both PAL and NTSC signals, just adjust the timings in software accordingly.

Source:Pontus