Composite to S-Video
Interfacing a composite signal to a S-Video signal is always a little bit tricky. Composite signal use one wire to transmit the composite signal, that is the luminance and the chroma. S-Video use to wire for that, one for the luminance (Y), one for the chroma (C). It is why S-Video is also called Y/C.
It is expensive converter on the market. Such converters are specific to the norm you want to convert. We will see here a very cheap alternative, a simple connector that will archive a very good result.
This connector will work in both ways, but of course, the result will be better when converting from composite to Y/C. That because when converting this way, the orifinal sugnal will not be degraded. The other way (Y/C to composite), the resulting signal will not be Y/C anymore but composite.
Schema
Beside the connectors, the circuit use a little 470 pF ceramic capacitor.