[Coco] S-Video mod for Coco1

[Tormod Volden]

On Fri, Oct 18, 2013 at 12:28 AM, Tormod Volden wrote:
> I also tried connecting the LM1889 pin 13 to my S-video chroma input,
> both directly and with a 0.1 uF capacitor, with no luck. I also tried
> tying the pin with a 1.8kOhm resistor to ground. However I see that in
> most examples it is followed by an amplifying stage. These stages are
> always inverting but that should not matter for the color signal.
> However a impedance matching stage is required to make a 75 Ohm output
> resistance. I'll try that later. Not sure how the Spanish Spectrum
> guys got away without it (on the diagram with the red marking).

I got it to work with a simple emitter follower (see
http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=5&t=4470). The
quality improvement is not so impressing but it is a start. Some
tuning and shielding will probably help.

Tormod