I'm struggling (to put it quite diplomatically!) to understand your schematic as posted... it unfortunately follows the current horrific convention of "this is a diagram of visually disconnected parts and signal labels and it won't make any sense until you stick it into a computer program, unless you spend multiple hours working out by label exactly which signal goes where and then redraw it by hand".

I learned to draw schematics based on the way they did it for 80s home microcomputers. Go look at C64 schematics online, you'll see what I mean fairly quickly. I can read those... and the ones for my Amstrad PPC640... and for the KIM-1 and Acorn System 1 and dang near everything else from that era...

Yet when I first saw the schematics, as provided on the UK Lo-Tech site, for their version of the famous XTIDE card, it took all of maybe three seconds for my eyes to cross... I spent literally three or four afternoons redrawing it to be human-readable. It was entirely inscrutable otherwise, except to whatever abject coding failure of an electronic design suite spat it out originally.

In the case of your schematic, I see two VGA connectors, four resistors, four Schottky diodes, a 4-position DIP switch, and a slice of mystery meatloaf in the lower-right corner that apparently escaped the local elementary school cafeteria and struck out on its own. I have no idea what on Earth (or elsewhere, for that matter!) that box is or what it does, as it's not even labeled, and I cannot fathom for the life of me how any of it connects to the rest.

Forgive the soapbox, but... this isn't a matter of me being "old-fashioned" and needing to "get with the times". This is not an "okay boomer" sort of thing (and I'm a millennial anyways). This is a simple basic fact of design, that is pretty well universal across all fields under that overarching term -- or, rather, an absolutely textbook example of what happens when you ignore that rule.

The rule is very simple: if you want to communicate an idea, you have to do so in a way that your intended audience can understand.

Schematic diagrams are what amounts to a visual descriptive language. What I'm seeing here is a bit like trying to speak English but without using any verbs... could you read (in a way that let you understand it, obviously!) Shakespeare like that? or Tolkien? or Poe, or Arthur C Clarke, or Jules Verne, or Agatha Christie, or anyone else for that matter...? I couldn't, any more than I can understand this.

You wouldn't use an operating system with an incomprehensible interface (and neither would I!)... so why make schematics like that?

Please redraw your schematic in human-readable form. Alternatively, if you haven't the time, provide me with a complete text description and I will draw it for you (I'm an artist as much as I am an electronics and computers nerd, so straight lines and grid paper are very much the order of the day!) -- but you must also promise to upload the schematic I provide, for others to use, once I've done it. I believe quite deeply in the sharing and spreafing of knowledge, not hiding or restricting it for any sort of private or personal gain.

LOL, that's an Eagle schematic you are viewing. Actually all the information you need is already in the picture.

Briefly there are two ways to designate a connection in EDA software, join with a line, or join with a label. In the latter case, all matching labels are in the same net. So to convert that schematic you only need to draw lines from LabelXYZ to all other instances of LabelXYZ.

Now I'm not too fond myself of extreme use of labels, they have their uses, but a lot of makers use this method, just look at schematics around here, but EDA software knows what you mean and will create the same circuit board whether you use lines or labels, or a mix of them. It's also possible to have something in-between by using buses which help to make signal flow clear.

By all means redraw that schematic to help yourself but if you do it outside of EDA software, other people will not be able to reuse your file to generate a circuit board, a bill of materials, etc.

See what you're missing by ignoring EDA software?

Aside from the missing component label and explicit connections, I roughly agree with your assertion that there's enough info. Care to provide the connection info and ID that box?

Re EDA software... lol... I've bought a custom PCB exactly once ever, and it was one someone else designed. Generally I've neither the need nor the income. While I won't get into it publicly (too many people unwilling to provide the patience to properly understand and just make fools of themselves with stupid assumptions and knee-jerk off-the-cuff interjections, stupid ones) suffice to say that I operate on a shoestring budget... with a *very* worn shoestring. If I had to ask OSH Park to send me a PCB for literally any circuit, I'd be screwed forever.

I build on perfboard. Chinese eBay perfboard.

It doesn't usually go well, but that's generally the fault of ordering the components from the same place. eBay chips don't work, but even Mouser's $5 "cheap hobbyist" shipping is a considerable drain on my resources.

My BoM is a note on the side of the circuit listing components and values, just like you'd have in an old Nuts N Volts or Practical Electronics article in about the same place... ;)

I miss nothing from EDA software, in either the sense of losing out on a supposedly-useful feature, or in the sense of feeling a sense of loss as a result of its absence... actually, technically that's a lie, as I do -- in the former sense, only, fortunately -- miss both the hassle of arguing a piece of obstinate software into understanding me while it's trying to show how much smarter it is than I am (I *hate* that!) and the experience of designing a schematic diagram (etc) that can only be understood properly by machinery.

Speaking as an engineer, an artist, and a designer all at once -- if I worked for *any* company and could do no better than to produce a schematic *that* abjectly unintelligible during product development, I'd not only resign on the spot, but I'd shred the schematic on my way out. Likewise, if I was overseeing someone doing that sort of work, and that's what they produced, if *they* didn't resign on the spot, I'd fire them for it -- and if I was a prospective customer and was shown something of the sort at any point during the sales process, I would immediately terminate that encounter and find another company.

Design is a matter both of engineering and of communication, You absolutely cannot neglect either of those within the process and still avoid bad design. Poor engineering is bad design -- that goes almost without saying -- but if you can't communicate intelligibly *about* that engineering afterwards, that is unavoidably also bad design.

Good documentation is just as important to *any* design work as the rest of it. Neglecting that effort is every bit as bad as giving a professional CNC guy a napkin sketch of what you want made with measurements written in fractional inches and without specifying tolerances... /hard_cringe

If that's typical output for Eagle... ha! I lose absolutely **NOTHING** except incredible frustration at being limited to producing such cryptically hieroglyphic "documentation" (and I use that term *incredibly* loosely!), and the money and time that go into learning such a "tool" (that, rather, makes one into a tool -- at least in the pejorative sense!) for the supposed privilege of that experience.

You can keep your Eagle. I don't want it. I have a pencil and I have grid paper, and I will keep those and keep to them -- and I will be a better person, and a better engineer and designer, for having done so.

I think that it is too simple a design to understand to give more importance to the design of the scheme, I am sorry but I do not plan to carry out any correction, although I appreciate and value your suggestions

Now for version 2.0 I have developed it in KiCad, I think you will find the layout much clearer.

NOPE!

Things connect to other things. You have a cloud of unconnected 'function blocks' -- for lack of a better term -- that each perform a task but are otherwise floating about rather too independently... and I *still* can't figure out what the component in the bottom-center is or does.

It should look like a flowchart. Everything should be connected to everything else. Start-middle-end.

Whoops! Well look, I've tried it ;-)

Replying here because there's a limit put on... there shouldn't be... but...

I do appreciate it :) If you can tell me what that bottom-center box (I think it's marked '51'?) is and does, and what connects to what, I might just make you one of my own home-cooked schematics later... ;) You're welcome to hit me up in the chat (the speech-bubble icons up at the top there, on PC, or "My Messages" in the menu on mobile, they changed it recently).

It is a 4P2T Switch. The COM pins are inputs, NC and NO are output pins bridged with the COM pins depending on which of the two possible switch positions it is in, therefore, they are outputs synchronized with the only two switch positions.

You should have made a 4P2T symbol instead of falling back to a rectangle. It's fairly easy to modify the SW_DPDT_x2 symbol to have 4 units instead of 2. Unfortunately I can't include an image in this comment so you'll have to look up SW_DPDT_x2 in the library to see what the symbol looks like. I'll paste the SW_4PDT symbol I derived here.

I also see there are two pins for the shield. You'll need to make a unit E containing pins 13 and 14 for that, and tick the box Units are not identical.

For the DCM file:

$CMP SW_4PDT
D Switch, 4 pole double throw, separate symbols
K switch 4-pole double-throw ON-ON
F ~
$ENDCMP

For the LIB file:

#
# SW_4PDT
#
DEF SW_4PDT SW 0 0 Y N 4 F N
F0 "SW" 0 170 50 H V C CNN
F1 "SW_4PDT" 0 -200 50 H V C CNN
F2 "" 0 0 50 H I C CNN
F3 "" 0 0 50 H I C CNN
$FPLIST
 SW*DPDT*
$ENDFPLIST
DRAW
C -80 0 20 0 0 0 N
C 80 -100 20 0 0 0 N
C 80 100 20 0 1 0 N
P 2 0 1 0 -60 10 65 90 N
X A 1 200 100 100 L 50 50 1 1 P
X B 2 -200 0 100 R 50 50 1 1 P
X C 3 200 -100 100 L 50 50 1 1 P
X A 4 200 100 100 L 50 50 2 1 P
X B 5 -200 0 100 R 50 50 2 1 P
X C 6 200 -100 100 L 50 50 2 1 P
X A 7 200 100 100 L 50 50 3 1 P
X B 8 -200 0 100 R 50 50 3 1 P
X C 9 200 -100 100 L 50 50 3 1 P
X A 10 200 100 100 L 50 50 4 1 P
X B 11 -200 0 100 R 50 50 4 1 P
X C 12 200 -100 100 L 50 50 4 1 P
ENDDRAW
ENDDEF

Thanks for the suggestion Ken Yap, I'll keep that in mind for future updates.

The more I look the more I like it. Very neat.

Thank you!

can it be bought ready built? 

Yes, from my tindie shop: https://www.tindie.com/products/spark2k06/monochromevga-20/

Thank you for this project! I built the SMD version - I found it challenging as it's the first time I've I worked with this sort of component, but was able to complete the kit within an hour.

Thank you for supporting the project. Yes, I deleted the SMD version because several users suggested it to me to facilitate the assembly, and the truth is that there is nothing that justifies that the components are SMD, there is a lot of space on the board. Thanks again and I hope you enjoy it.

Now, in version 2.0 it is also possible to mount it using SMD technology, I have put fingerprints with mixed technology :-)