DIY Scart Switch and Splitter - function switching

[Filurkatten]

Hi.

I'm planning a new scart switch project.
Have anyone used the chip MAX9655 IC for a Scart Switch Splitter project?
Looks good from reading the datasheet:
https://datasheets.stg-maximintegrated. ... AX9656.pdf

I'm thinking about replaceing my current 8input switch with a new built one. My old one uses CBT3245A and has some issues.
My current line of thinking is to use 7 MAX9655 in a tree grid to avoid interference and a to messy busline.
4 chips for first stage of input, 2 chips for second stage of input and 1 chip for last stage of input.
Would this be a good aproach?

The brains of the switch is going to be a MCU, Raspberry Pico, PIC or Arduino, whatever I have at hand at the moment.
For audio switching I'm leaing towards standard 4053 chips.
For video amplification so I can use two outputs the THS7374 chip looks good.

I know that THS7374 has some sort of filter that can be deactivated to improve sharpness.
Do anyone know if MAX9655's filter is going to give any issues?
Also, how would daisychaining 9655's affect the video quality?

Input from consoles to first set of 9655 is going to go to a 75ohm resistor to GND and then throu a 0.1µF cap.
Second set of 9655 surley wont need the extra caps right and only the resistors?

Lastley what Sync Separator is recommended? LM1881 or LMH1980/1981?
Maybe there is a good Sync Separator IC that also has a way to implement horizontal shift?


That was many questions and I hope maybe a couple could be answered!
Maybe there is a better forum for these kinds of questions, if so please give me any tips!

Thanks in advance.

[Filurkatten]

A update.

I have done some more planning and is switching up some components.
Goal; 8 inputs, 2 outputs (1 scart, 1 RGBS), 1 extra Audio output, automatic scart detection, selectable sync stripper, selectable H-Pos adjustment, force aspect ratio (my TV needs pin8 at 12v else it will default to widescreen)
Stripper, H-Pos, Aspect Ratio settings should be saved per input with MCU.

MCU will most likley be a raspberry pi pico because I got a bunch laying around.
It will handle scart input detection by measuring sync frequency. Should be doable I think.
Go throu one input at a time checking for a 15kHz signal.

Sync stripper will be a LM1881, I also want to incoperate a H-Pos shift.
Wich of these shifter circuit would you recommend?
https://playoffline.wordpress.com/cable/rgbshifter/
https://members.optusnet.com.au/eviltim ... tysync.png
I have tried the first one before with success but the one from tim seems to be easier to control with the MCU.
Replaceing the VR1 trimpot with a voltage of 3-5v if I understand it correctly.

The signals will be amplified with a THS7374 at the output stage to allow two monitors to be connected.
What about audio? Should I have a TL074 buffer/splitter circuit or the like?

For switching the inputs I will use the TS5V330 as the MAX9655 isnt available to buy anywhere.
The TS5V330 will be arranged in a tree structure. 7chips.
For switching audio 74HC4053 will be used.
For switching sync signal to the sync stripper and H-Pos correction 74HC4053 will also be used.

Selecting aspect ratio, Pin 8, a circuit that switches between 5v and 12v from a GPIO of the MCU will be used.
Would a circuit like this work?

photo to google


Electronics is only a hobby for me and this is quite a large project so there is most likley plenty of things that I have missed or should do in a better way.
Any input is appriciated!

[SuperSpongo]

Sounds cool!
How are you planning on implementing the horizontal shift function? I've seen this circuit working: https://playoffline.wordpress.com/cable/rgbshifter/ but I was wondering if you had another in mind.

[Filurkatten]

Either that one you linked or the one by tim;
https://members.optusnet.com.au/eviltim ... tysync.png

The one you have linked I have tried with success in the past but I think Ill use the one by tim in this project as it seems simpler to control with a MCU.

I do have limited free time as I have two kids so the project might be slow but steady working.
First planning and selecting parts, then circuit design and testing and last PCB.
Hopefully I have something tested and working this year. XD

Ill try to keep the thread updated.

[SuperSpongo]

I'm looking forward to a bill of materials and a cost estimate

Are you planning on selling complete units, DIY kits, or open-source everything?

[Filurkatten]

Its mostly for myself, but if I get everything up and running I'll make it available as opensource.

My guess is that it could be quite expensive.
But planning first, cost reduction later.

[Filurkatten]

Got some components in the mail so I can start testing the theory of some of the circuits.
Will try do make time for it in the coming weeks.