Combining RGB and Sync to make a composite signal for B&W

There are a few old Sony IC's that will take RGB in and spit out Y/C or Composite Video. This is the first one that came up:

 

https://console5.com/techwiki/images/f/fb/CXA1145PM.pdf

 

You really only need Luma though, if the image is black-and-white to begin with. So you can stop there :) Admittedly i've never used one of these, but they look like they'd do the job.

 

Or if you can find schematics for any of the homemade RGB to Component converters they'll do the trick as well. Zebidee had some on here, and Mikechi has some on the Shmups forum - i think he just adds C-sync into the Y line, but coming out of an LM1881 so it's buffered. Again you will only want the Y output in any case.

Sony CXA2075 is a better choice, more modern version of the 1145 and requires fewer external components. As suggested you could either use the composite output or just use the Luma output from s-video. Edited December 9, 2019 by Frank_fjs

Thanks for those suggestions guys!

 

I didnt know they existed!

 

 

I was hoping for some feedback on the design and a bit of a discussion maybe... I figured the concern with my design might have been whether it would continue to opperate, or detroy sonething in time because of no coupling cap as you see a lot on b&w designs.. also this..I'm assuming the jama edge connectir of the multi outputs ttl. Apparently ttl can sink up to 16mA.

 

So my design falls within safe operating levels. V=IR

Vmax = 5V Resitance pathway to any ttl ouput is 33Ohm so current is 15mA max. But the signal hovers between 2 and 3.5volts most of the time. Even lower during retrace times.

 

That's my reasoning. Happy to hear other people opinions on this. ;)

Edited December 9, 2019 by taito

will your friend sell the Jatre specter invaders board ?

I have 2 here both dead , maybe i can get one working again.

will your friend sell the Jatre specter invaders board ?

I have 2 here both dead , maybe i can get one working again.

 

You'll have to indicate how much you are willing to pay, I'll ask him, but not likely. :)

 

Update: I asked and he's not wanting to part with his board.

Edited December 28, 2019 by taito

Looking back, I think I got a bit of Jatre Specter space madness! lol