I have decided to re-visit this project now.
To summarise:
I have a new TV that has only one analogue input; component video input. (YPbPr / YCbCr).
I have all my old retro consoles hooked up via an Extron MVX84VGA-A video switcher. I have made custom Component cables for each console and one for connecting the output to the TV. This is working great! However some consoles only have SCART output (RGBS). I can no longer use these devices so I would like to build a passive converter. (see schematic I found online).
I attempted this before with minimal success. I got a picture in colour but it was very noisy, due to using the TL072 as an op-amp.
This is the old thread:
https://www.eevblog.com/forum/projects/rgb-to-component-(ypbpr-ycbcr)-video/The two main issues I have encountered in this project are the cost of the LM6172 and also the power supply.
I would also like to, adapt the circuit so I can switch the converter on/off so that I can put it in-between my Extron input selector and TV. That way when I want to use a device that already has Component output I can bypass the converter in this unit.
The first think I want to tackle is the power supply.
Could anyone shed some light on the workings of power supply shown in the schematic?
I tried using a USB power supply feeding a LMC7660, however the 7660 could not handle the current used so the output voltage would just drop to around -2V.
So what would be a good alternate solution? Perhaps a linear AC supply with a 7805 and 7905?