On 8/7/2012 5:55 PM, kevin@hackaday.com wrote:
you still need a way to sniff a 3.something mhz burst
signal 50-60 times a second and a mux to switch the signals tween the boxes (which sounds so ghetto)
This is the easy part. NTSC (and PAL) TVs have a "color killer" circuit that detects a presence of the color burst and turn on the color decoding. If there is none, a filter is turned off to extend the bandwidth. More or less the same functionality.
Detecting the burst is not all that hard. You have to have a PLL that locks on the color carrier (3.58 MHz). Apply this restored carrier rotated 90 degrees and gated color burst to a phase detector and you get pulses on every line.
-Alex.