Hello All,

I know electronics at a very basic level. And I know what I want to achieve Im just stuck as to how to get there.

What I have is a circuit that converts 23pin commodore amiga video output to 15pin pin VGA connector.

The problem that I am having is that the horizontal video frame is 15.625khz and of course a vga monitor requires 31.5khz signal so I would like to double the frequency of the horizontal sync so that it falls within the correct range.

Can anyone tell me how this can be done preferably very acurately and preferably with a nice IC to make it pretty.

I would realy appreciate some ideas.

Cheers in advance.

 

Have a look at either SDA9400 or AL250. These are single-chip scan converter/doubler. Probably not that easy to find and use. If want the easy solution, you could either buy a scan doubler box, probably less than $100, or get a multiscan monitor that is able to scan down to 15Khz.

 

I did try a commercial converter made by a company called Mayflash - it doesnt work as advertised and Im very annoyed about it

It will not output to VGA monitor because the monitor cant get DDC1/DDC2 signals from it and when I tested the unit all I got was block graphics on the screen nothing readable from the box menus, when the unit was on, no VGA signal
when it was off I had vga picture.

Only practical use for this box = door stop, I emailed them over a week ago and have heard squat after shelling out $55 USD

 

This has been suggested as a possible solution any comments or pitfalls I should look out for would be appreciated.

http://www.maxim-ic.com/appnotes.cfm/an_pk/3327

Cheers in advance.