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RGB to Component Converter

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paul_g_787:
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?

Benta:
1: what's your supply voltage (options)?
2: are you certain that your devices only output RGBS or could it be RGBY?

paul_g_787:
I need +5v/-5V split rail for the supply voltage.

Yes they are RGBS:

The Extron only supports clean sync, so the cables for the RGB consoles have a LM1881N in the cable to strip the sync from the composite video.

Benta:

--- Quote from: paul_g_787 on October 17, 2021, 07:27:20 pm ---I need +5v/-5V split rail for the supply voltage.

--- End quote ---

My question was: what's your supply (=INPUT) voltage? What's available to produce +/-5 V?

paul_g_787:
Oh I see. Hehe :)

I have two options.

I could power the device from USB. So +5VDC.

Or I could power it from the 240V AC mains, which I would perhaps prefer.

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