composite to VGA

[spoyalloy]

While having a tussle with the vertical hold on my Phillips CM8833 I wondered if I could drive a VGA monitor from a PC with the composite signal from the birdsnests that I keep assembling. It turns out there are muliple little converter boxes that do the trick on Ebay etc. Has anyone got any views (pun!) on those?
I would be looking to output from my circuit a regular HSYNC (50Hz), VSYNC (15.625Khz) (often from a 6845 IC) and a video signal, all at 5volt logic levels. Of course, I currently have a range of favourite little circuits (a couple of gates, resistors and diodes) to combine those signals to a sort of ragged PAL signal, and currently I squirt that into the CM8833.
In truth, I see that converter box as a dirty fix - I like to know what is going on in a circuit. It would be even better if I could avoid having to mix those signals before conversion, so has anyone come across a homebrew circuit to accept TTL syncs & signal, and to output a VGA signal?

Paul, Portsmouth, UK

 

[rmay635703]

I have a fourdja that does it well.

Find a scan doubler

 

[Amygdala]

This is an old thread, I thought I'd mention I've never heard of Phillips CM8833, Of course I'm in the US and would want an NTSC equivalent. Amazon sells several "Arcade Game RGB/CGA/EGA/YUV to VGA HD Arcade Game Video Converter Boards" put out by several different Chinese companies (although they seem to be the same product). They're all open, not in a box or container. Considering the convenience, or rather inconvenience of making a homemade, "hand-rolled" solution, I'm more than happy to settle for a "dirty fix". PS Amazon shows the product with the exact name I provided is "not available". I am not promoting any specific product.