🚀 go-pugleaf

ron@vicorp.com (Ron Peterson) writes:
>Is there a cheap way to convert RS-170A RGB&Sync to NTSC?  I seem
>to remember an article in Radio Electronics but can't find it.
>Would it be as simple as using a high speed op amp to sum them?

If you just want a B&W signal, yes, you don't need much more than
a few resistors and a video-bandwidth op amp.

But if you want colour, it's much more complicated.  Basically,
you need to convert RGB into Y (luminance, the B&W signal above)
plus two colour difference signals (R-Y, B-Y), then lowpass filter
the colour difference signals, then use them to amplitude modulate
two colour subcarrier signals.  The subcarrier signals are derived
from the same crystal oscillator, but with a 90 degree phase shift
between them.

There is a single chip that does most of this for you, if you're
not too fussy about quality.  I don't know its part number, though.

	Dave