Scandoubler schematics

[skurk]

Ok, I know this has been discussed before, but I haven't found any real info yet.  And, it must be said, I have no idea what to expect here. :-)

So, does anyone out there have the schematics for a scandoubler?

I'd love to build one that slips into the RGB port.  I can get my hands on most parts, and the price is not an issue at the moment.

[amiga_3k]

Those schematics are rather difficult to find. Depending on your electronics-skilss you could have a look at AverLogic
they provide a chip doing a part of the trick: Scandoubling. In front of it, you probably need some kind of RGB to composite conversion schematic. That part could possibly be handled by Motorola's MC1377.

So, if you can think of a schematic joining both chips in the correct way and make your design as such that you basically design a board meeant for the internal Video-slot (and build an converter such that it can be hooked to the external RGB) you might become a littlie hero ;-).

[skurk]

I did stumble upon this one, though.  Looks plausible to my untrained eye, and the Amiga RGB port provides all the required input.

[countzero]

If you want to plug in to the rgb port, you have to perform three tasks :

1 - decode the analogue RGB signal to digital (ADC)
2 - double the frequency
3 - convert the digital signal to analogue (DAC)

but, you can skip the first step if you use the digital signals directly from the amiga. For big box amigas, these are provided on the video slot. For desktop amigas you need some adaptors clipping on chips (well denise or lisa).

I asked this question before in another forum and got some valuable answers. You might want to check that.

[motorollin]

So, what are the chances of a schematic for a video slot scandoubler? :-D

--
moto

[countzero]

well, it shouldn't be too difficult if there were chips which handled the scandoubling. The averlogic chip seems good, but it says RGB 565 which sounds inadequate for AGA screenmodes. Though there are 8 bit DACs in the spreadsheet so I'm not sure if it actually performs real 8 bit scandoubling.

[motorollin]

This sounds like a job for Individual Computers. Jens are you reading this? :-)

--
moto

[a1200]

The big problem I have found with scandoublers is they get VERY hot. Why is this? It is because they do it in a rudimentary way to keep the cost down? If money was not a consideration, surely it wouldn't be hard to get a 15Hz signal, input it into a SVGA graphics processor and produce a 30+Hz signal?

As I understand it, your bog-standard scandoubler literally doubles the 15Hz signal, surely inputting the signal into another processor for output would keep the things from running so hot?

[James]

What about these?
http://www.ramelectronics.net/HTML/video-to-vga.html

Couldn't they be modified in some way to take the signal from the RGB port?

[skurk]

I already own a similar item (link) but the quality from the composite is horrible.  Just horrible.

The ones with component sound interesting, though.

Are there any RGBI->Component cables/converters available?  I think that, plus one of those component to VGA adapters would produce an OK picture.

[Colin_Camper]

Hasn't this issue been thrashed over, ad nauseum?  :-)

Best Scandoublers/FFs = plugged to chipset or built in (A3000) = horrendous price and zero availability!

Available Scandoublers/FFs = Mediocre performance, horrendous price.

LCD TVs = Cheaper than either the above, excellent performance and display.

[a1200]

I use an LCD display for my A1200 see:

http://www.amiga600.net/temp/a1200_base.jpg

But! I cannot use it realistically any higher than Hi Res becuase of the flicker issue.

[skurk]

Colin_Camper wrote:
Hasn't this issue been thrashed over, ad nauseum?  :-)

Probably, but it never hurts to search for new solutions.

Component to VGA adapters are cheap on ebay, $15 and up.  If it's possible to extract a component signal from the Amiga RGBI, then we have a decent and affordable solution.

[alexh]

Hope this ends all nags

http://amigahardware.mariomisic.de/cgi-bin/showhardware_en.cgi?HARDID=1771

A 24-bit video slot scandoubler implemented using 2x A3000 AMBER deinterlacers.

http://www.gb97816.homepage.t-online.de/a2320_aga.htm

All the project files, schematics and CPLD code included

http://www.gb97816.homepage.t-online.de/download/a2320_aga.zip

countzero wrote:
The averlogic chip seems good, but it says RGB 565 which sounds inadequate for AGA screenmodes.

It's only RGB 16-bit (565) and only gives 16-shades of Red and Blue. Just like the DCE scandoublers Flicker/Scan Magic etc.

Though there are 8 bit DACs in the spreadsheet so I'm not sure if it actually performs real 8 bit scandoubling.

It doesnt. It only has 16-bit input, but 24-bit output. (It needs that incase you do Y'CbCr to RGB conversion.)

[amiga_3k]

So basically, now Clone-A is functioning, Individual Computers should now re-implement Amber? ;-)