encouraged by the success (and fun) of building these circuits from @schaferob whiteboard-schoolhouse (just realised iv been calling it your whiteboard fun house this whole time lol) was thinking would like to give this colorizer a go too. since this will likely lead to some more questions lets start a new thread !
some details (pulled from this fb post )
- runs on (single) 5v power
- for black & white ntsc video
- 2 full colours plus black
discussion around adapting for pal
there is more on this in the fb comments, but in summary (@BastienL writes ) :
actually I don’t think it makes it particularly more complex. I guess you only need to replace the quartz oscillator by a proper frequency quartz, and then as Rob said, a flip flop can take care of dividing the horizontal sync signal by 2, with 50% duty cycle, which means the output signal will remain high during a line, then will go low during the next one, and so on. The 180° shift is already implemented in the circuit, so using the signal generated before, you should be able to drive the two XOR. Then instead of taking the signal for the burst reference directly from the oscillator, you should take it at the output of one of the XOR, so it also get inverted every other line.