QL Pico VGA

[ones' complement]

Interesting development by Holmatic on forum.tlienhard.com

https://github.com/holmatic/video_if_ql_vga

[bwinkel67]

That looks ridiculously simple and inexpensive. Under $10 in parts.

[martyn_hill]

Wow!

I love Marcel's adapter, but I shall definitely be trying out this little project!

[afx]

Cool ... ... a clever solution for a VGA output for the QL!!

[gbejniet]

This looks great, I was hoping someone might have a go at doing this at some point.

I am guessing that the Rs on the QL side might also provide some meaningful protection for the ZX8301 (given what I've read elsewhere?)

[Peter]

I am guessing that the Rs on the QL side might also provide some meaningful protection for the ZX8301 (given what I've read elsewhere?)

Crucial is the decoupling of the actual video signal from the ULA lines, which is given here.
But only if this adaptor stays connected and the signals can not be touched.
In my experience, electrostatic discharge is a bigger risk than the resistive load conditions on the video lines.

[bwinkel67]

Which, I assume, has to be done before the RGB video connector (and is not on a base QL).

[Peter]

There are alternative RP2040 modules which are smaller, and I designed a PCB to turn it into a miniature QL RGB to VGA converter:

Resulting in a litlle adaptor, which I will mount inside a D-Sub case.

Since the composite video pin in my QLs is unconnected, I use it for the 5V supply. The converter needs less than 20 mA and a little electronic fuse can be used for protection, in the extremely unlikely case a QL device uses that signal (I have never seen any).

Lots of compliments to Oliver, who wrote the firmware and made it available!
Without doubt, this is the best QL video converter ever!

[Derek_Stewart]

Hi Peter,

I have been following the discussion on tlienhard.com forum, I did not comment, as I do not speak German.

I have ordered a PICO to make an adapter, but I thought the PICO VGA adaptor was a good idea, your enhancement looks great.

Another execellent item for the wishlist.

[Peter]

Hi folks,

please find attached Gerbers, schematics and placeplan for my Mini VGA board.
At current stage, the VGA HSYNC and VSYNC lines have to be wired according to the following photos:

GP16 (VGA Pin 13, HSYNC)

GP16.jpg (15.09 KiB) Viewed 12788 times

GP17 (VGA Pin 14, VSYNC)

GP17.jpg (12.32 KiB) Viewed 12788 times

Maybe Oliver will provide alternative IO for regular module pins later. When using HD-Sub with solder buckets, and a PCB is thicker than 1mm, it will not fit between the pin rows. (You see that in my previous post). I recommend to file off 0.3 mm of PCB border in that case. Or use HD-Sub with pins.

Good luck!
Peter