GreenAntz RGB to component transcoder

[net_terminal_gene]

Posting a review because Andrew (Zebidee) absolutely deserves it.

I picked up a GreenAntz v1.95 to run VGA/RGBHV → Component (YPbPr) for Batocera-CRT-Script into a consumer CRT (Philips 20PT6341/37). The results are exactly what I was hoping for. Excellent color saturation and depth (not washed out like some transcoders), a clean image, and rock-solid sync. Once dialed in, it just works.

I did end up discovering that my first unit was faulty. After a few hours of runtime, the image would start to flicker and eventually become unstable. What really stood out, though, was how Andrew handled it. He was prompt, patient, and genuinely invested in figuring out what was going on. We went through power, sync, and environmental variables together, and he did a great job explaining the possible causes in clear, technical terms without hand-waving.

Once he identified the root cause (a build-related issue on the PCB), he didn’t hesitate. He built and thoroughly tested a replacement unit, ran it for extended periods to confirm stability, and shipped it out. The replacement has now been running 100% stable for me with zero issues.

This kind of transparency, communication, and follow-through is rare, especially with small-run hardware projects. Andrew clearly stands behind his work and cares about the community and the product. I wouldn’t hesitate to recommend GreenAntz to anyone looking for a high-quality VGA to component solution. 

[Zebidee]

Thank you Mikey! So glad the replacement is working out right for you.

Turns out the issue was caused by me not properly cutting a tiny bit of trace beneath the blue sync LED. GreenAntz is in continuous development and the boards I've been using were never designed to have a sync LED, I it is retrofitted into the design. When I get some new boards done the sync LED will be incorporated as a standard feature, no hacking required.

Now that they have the sync LED, I find it invaluable for troubleshooting setups.

OTHER NEWS

The latest design (v1.95) restores the slide switch to select between Csync and Vsync inputs! I had removed the switch for v1.94 as I was happy with GreenAntz "autoswitching" to composite sync when there is no Vsync present, I deemed it unnecessary. Unfortunately CRT_emulator does *NOT* turn off Vsync signal when composite sync is enabled. As noted in my earlier post, this could potentially result in "unrecoverable" situations, requiring rebooting into safe mode and uninstalling drivers.

The restored slide switch forces composite sync mode mode when enabled (it actually disconnects the Vsync input and "blanks" it, pulls it to logic "high").

[newshrimp]

Can't wait to try this out

[Austin_MVP]

Hi! Learning about ways to use Batocera on a CRT has led me to the Discord server/GitHub page and now here.

I have an NTSC Sony Trinitron CRT with component inputs. Hoping to get a Batocera setup running on it in the not so distant future.

[metadatum]

awesome to see hardware for analog signals still being developed and improved today.

[zone72305]

This looks promising. I recently got into the CRT rabbit hole and wanted to connect my PC to the CRT without compromise. Though I'm wondering if my PC can output 240p/480i first. I have a AMD R5 200 series card on it. I'll look into that too.

[Zebidee]

A quick update:

The new GreenAntz (v2.1) will soon be available!

GreenAntz v2.1 is fully SMD (surface mount design), I've done away with the through-hole components where possible. This means is is much smaller than the old GreenAntz, about 60% or the original size, but retains all the same great features:

- accurate composite sync generation and integration into Y signal at appropriate levels
- sync autoswitching (and manual override switch also included)
- precise voltage regulation (avoid "flickery" colours).
- optimised video amplification (more consistent, right levels, fully saturated colour)
- optional low-pass filter (9.5Mhz 6-pole butterworth) available
- optional 5v landing site for innovative project applications (e.g. inside a JAMMA cab, powered by same DC PSU as game board)
- PCB-style offset legs allow screw-in mounting (ideal for arcade cabs)
- Pots to allow precise tweaking of Y, Pb & Pr outputs.




Smaller size less than 60mm wide, and about 75mm long (including jacks).


GreenAntz v2+ also includes a pot for adjusting Pb output, so now you can adjust all three video channels (Y Pb Pr) to suit your own needs and preferences. These pots adjust video OUTPUTs, rather than throttling the RGB video INPUT signals like some transcoders do. This means there is no loss of picture information.

Going to smaller size and SMD components also seems to have provided some other less obvious improvements, including less signal interference and issues like parasitics often associated with through-hole builds. My assessment of this is perhaps less scientific than I'd prefer, except to note that when it works, it usually just looks good and works as it should.

Finally, despite the reduced size and profile of GreenAntz v2+, you can still provide alternate 5v power.


 
Screw terminals (5.08mm spacing) drop right in!


The images shown in this post are all of GreenAntz v2.0, a version only used for prototyping (green PCB). I am not intending to sell any of those. These prototypes have all been hand soldered and I can attest that soldering SMD boards takes about the same time as the old through-hole boards, best part of a day. Most of that is in the setup (solder paste and placing parts), the actual soldering (mostly with hot air) doesn't take that long. Would have saved a lot of time if I'd remembered to order a stencil (for applying the solder paste).

Anyway, within a week or so, I expect to have the new GreenAntz v2.1 boards in hand.  These ones I will be selling. The v2.1 boards will come partly assembled (~80%) by pick-n-place machines at the factory. This means I can turn them around quickly and into your hands faster.

If you want to get in early to order your GreenAntz v2.1 then please send me a PM! Don't forget that you must make at least one post before sending PMs.

PS - I am also currently investigating development of some kind-of enclosure or box. Follow this thread for developments!

[buttersoft]

Sweet, dude. Time to design a 3-d printed case, eh

[Zebidee]

Ond did a design a while back, and you can download the files from this thread. They could be adapted for the new slimline GreenAntz.

The only real difference is the new v2 models are not as wide.

In any case (no pun intended), I'm currently in discussions with potential suppliers.

I kinda like anodized aluminium, or plastic/polymer, but it may come down to price.

Next big question will be: what colour?

 

Sweet, dude. Time to design a 3-d printed case, eh

[Ond]

I'm on board with this -again-  . Great product, better than what else is out there imo. Anodized yellow cases please!

[Ond]

New GreenAntz 2.2 case design for Zebidee to mull over  Well it is green!

[Zebidee]

Wow, it looks very nice indeed Ond. Love your work, thank you so much!

Oh, I'm definitely mulling! Mull mull mull mull... "The Mouli Mullamatic, it work liiiiiiiiike magic", old advertising jingle some mates came up with for a music school assignment, they'd sing it a capella all the time, ear worm still stuck in my head after 25+ years....

I think it needs "GreenAntz" text there - if stylised is too hard, then simple text would do.

I've been juggling ideas to extend the LEDs to those holes. In theory the legs could extend from the PCB, so that the LEDs actually reach those holes themselves.

Alternatively, some 3mm fibre optic. Glue one end into the hole (carefully, so it lies flat) using either clear epoxy or even just superglue (gotta be careful with that stuff). A little pre-shrunk heat-shrink tubing, slightly recessed, could help it sit properly and increase surface area for glue to hold. The other end can be have more heat shrink tubing, longer, that also extends over the head of the LED, pre-shrunk to fit. Slip it on and screw the shell halves together. Maybe another big blob of glue or silicon inside the shell to hold it there.

Feels a bit fussy and fragile though, at least where it would be glued to the shell. Obviously I will have to experiment.

If we do fibre-optic tubing then maybe the LEDs can be the GreenAntz' eyes? That would be pretty wild.

Oh, and shell colour doesn't have to be green despite the name lol.

I'm already getting some prototype shells printed, basic version of this design (no logo, wings, LED holes). Will share some pics here in a few days.

[Ond]

You're welcome  Note, the case has been designed from scratch although I did use your supplied model as a reference.

More pics including added text.  You can see how the moldings work including the tubes to LEDs.

...and in my preferred color

I don't recommend any tubing/optical fiber etc.  The LEDS will be plainly visible when viewed from above which means less work for you. In testing I've found that white optic tubing does not work very well anyway.  I'd keep the text under the logo plain. Stylized font will look too much IMO.

[buttersoft]

nice case design, Ond!

Zeb, i like to use round perspex rod for light pipes on my designs. Hole tolerances on the print can sometimes be tricky, but once you dial it in you just cut a short length of rod, file it flat on the top end, and press-fit into the hole.

[PL1]

Looks great, Ond. 

Instead of the current straight-sided LED cylinders, you may want to consider using tapered cylinders.

One way is to slightly increase the outside hole diameter so there is a (5-15 degree?) larger viewing angle -- no light pipes needed.

Otherwise, you can add a thin, 6-8 mm tall vertical slit across the bottom of the LED cylinder walls (red lines) and use a very slight taper on the bottom 1/4 or so of the cylinder.
- The slit will allow the bottom of the cylinder walls to flex a bit for better friction while making the tolerances less critical.
- This makes it easier to insert the light pipe into the top then press it down for a flush friction fit.
- For more flexibility, you could add a second slit so the bottom is divided in quarters instead of halves.


Scott

[Zebidee]

Looks great Ond! The text font looks good too.

I had noticed a bunch of small things were different, and that is all good. I can see why you rebuilt the model. Thicker, longer inner shell on the top piece is good. Extended to meet the PCB layer. Speaking of...

The PCB layer is 1.6mm thick and must be accommodated. The top level looks right, but the model seems to be assuming zero PCB thickness. Think it just means lowering the screw posts, and corner/edge support bars, on the bottom piece. This issue is more obvious when looking at the USB/VGA ports (circled yellow).

The bulk/box/body part of the RCA ports is right up against the edge of the PCB, making me worry that the thicker inner/lip part of the top piece may bump into it. On my prototype model I sliced about 0.3 mm off the lip there. You made thicker! Anyway, you probably wondered WTF when looking at the model I sent, but that is why. I may have been worrying about nothing, it might all fit together fine anyway because the material is flexible enough etc.

Anyway we'll see when the prototype shells are here, and you'll know more once I send you a v2.2.

Thinking some more, the wings may need to be a little larger, the holes up to 4mm diameter, and moved a little further away from the body. Circled in red below. Checking again, some of my favourite cab screws (and used extensively by LAI), on closer look, actually have 4mm thread and just over 10mm wide heads ("button head needle point", various lengths, bought at Bunnings over a decade ago). Even my 2nd favourite cab screws have like ~8mm wide heads. Pic attached.

I hear your advice concerning LEDs on board too. I will probably experiment with fibre a little anyway, and ordered some 3mm fibre last night before hitting the pillows (or reading your response). So it is coming anyway. I can make the LEDs considerably brighter by just changing the current-limiting resistors.  Currently ( ) their brightness is throttled quite a lot. Designed to be visible but not distracting.

Butters, thanks for the tips about using perspex rods with LEDs, interesting alternative.

Thoughts welcome 

PS - Nice ideas Scott!

I like the idea of closing the hole with a light pipe, to avoid damage from spilled sodas and such. A drawback is that the LEDs would be less visible from the side, such as when installed on the in-side a cab.

It also occurs to me that these contexts are mutually exclusive - you don't really need an enclosure in a cab anyway, and you don't really have side-visibility issues on a coffee table. Even so....

Your side slits idea might further allow a compromise as it would allow the LEDs to be visible from the side (barely), while still mostly protecting from unplanned soda events.

Another thought is that LED visibility would not be an issue if the enclosure was transparent! 

[Ond]

All good. I have in fact allowed for the PCB thickness in the design. There is a gap there. I'll check your other requests soon.

[PL1]

the wings may need to be a little larger, the holes up to 4mm diameter, and moved a little further away from the body.

Agreed.  Better 6mm too much room between the screw hole and the side of the case than 1mm too close.
- Might be good to allow enough room for a socket if anyone wants to use a bolt/hex head fastener.

I like the idea of closing the hole with a light pipe, to avoid damage from spilled sodas and such. A drawback is that the LEDs would be less visible from the side, such as when installed on the in-side a cab.

How deep you install the light pipe might make the LEDs easier to see.

If you press the light pipe in so it is flush with the surface of the case, it will definitely be harder to see at a low angle.

If you start to put in the light pipes then place the case cover face down on a hard flat surface and firmly press down in the center of the ant head logo, that should seat the light pipes so they stand proud the same amount as the ant head logo does, increasing visibility.
- If this is how you want to proceed, consider adding an outline rim on the case the same height as the logo.  That would also make it easier to 3d print face down.

Your side slits idea might further allow a compromise as it would allow the LEDs to be visible from the side (barely), while still mostly protecting from unplanned soda events.

I wasn't suggesting slits in the side of the case, just a 0.5 mm wide by 6-8 mm high slit in each LED cylinder (red lines in this pic) for greater flexibility and friction to hold the light pipe firmly in place without adhesive.




Scott

[Zebidee]

I 100% believe you, but cannot see it in these images. Maybe a different perspective would help.

All good. I have in fact allowed for the PCB thickness in the design. There is a gap there. I'll check your other requests soon.

[Zebidee]

I was thinking along the same lines, about installation depth, and will do some experimentation.

Yeah, I was off on the completely wrong track about the slits. I see what you mean now.

How deep you install the light pipe might make the LEDs easier to see.

If you press the light pipe in so it is flush with the surface of the case, it will definitely be harder to see at a low angle.

[Zebidee]

A quick update to let people following know that GreenAntz v2.2 should be officially available from next week. I'm just waiting on some deliveries.

Even so, I've just sent some early v2.2 equivalent units out for keen gamers. I managed this by using the v2.1 PCBs and upgrading some components. Specifically, I changed the voltage regulator for a better performing part and tweaked it slightly to be even more consistent & reliable.

Thank you for your patience!

Enclosures will not be ready for a while yet -  keep following here for updates!

Attached: GreenAntz babies beginning their journeys to new homes.

UPDATE!!!

The v2.2 boards just arrived - earlier than expected! I will get busy putting a few units together now, and over the weekend.

[Zebidee]

GreenAntz v2.2

I've put together a bunch of GreenAntz v2.2 units, they are now available. I'm very happy with this latest design. I do not intend to make any more major changes after this, at least not for a long while.

v2.2 features an additional pot for Pb, now you can adjust all three signals (Y, Pb, Pr) across a reasonable range to suit individual preferences. In all cases the pots provide a typical or "standard" signal levels when set at about 40-50%. All GreenAntz boards are individually pre-calibrated to approximately 0.714pp output levels, though this may vary depending on signal input levels (that is, your different devices, video cards etc., may and do vary).

The only real differences from v2.1 are a new voltage regulator chip, some tweaking to that, and slight variations to the corner hole and LED positions to accommodate the new enclosure. For those who bought v2.1 units recently, you haven't missed out as the voltage regulator parts were upgraded to v2.2 anyway.

Price is US$50 + courier shipping including customs import charges. Please contact me via PM for Paypal and other details.





Enclosures


These early prototype enclosures are simple. They do the job and are sturdy. This prototype actually predates the models Ond showed us earlier - he has completely remade them since. A notable difference is no "wings" for external screws.


 




No logo yet, and that is a key reason why I asked Ond to help. I could have invested a great many more hours, learning hidden secrets of various 3D design software tools & techniques for myself - but Ond already has the skills and some obvious natural talent at it 

As can be seen in the pic below, the LEDs are still visible through the white SLA resin used, so that is an option for some colours/materials combos. I could easily make the LEDs a bit brighter on newly built units.





I've already mentioned that this prototype enclosure has no wings to take external screws. I have two minds about the wings:

- On one hand, the wings are practical for implementing arcade build projects.

- On the other hand, GreenAntz the enclosure looks just fine, maybe better, without wings - builders can just order the naked board, and use PCB offset legs to screw it down. The drawback with this is that you cannot both use the enclosure and screw it down.

So, I am interested in opinions about what people think: for the GreenAntz enclosure, is it better to have the wings or not. Please provide input promptly as Ond will likely be working on the design soon.

Other than that, I'd prefer to let Ond work out the gritty details for himself. Because creative work done under close direction or scrutiny is not much fun. I have sent him a completed v2.2 unit and the prototype enclosure, and will leave the rest to him.

Regardless, enclosures won't be ready for some time yet. If you ask "when", the answer is "soon". So hang in there. They are being designed to suit the v2.2 boards. They will not suit v2.1 or earlier boards. New GreenAntz units continue to be provided with free USB-C power cable and set of four PCB offset legs.

[PL1]

I've already mentioned that this prototype enclosure has no wings to take external screws. I have two minds about the wings:

- On one hand, the wings are practical for implementing arcade build projects.

- On the other hand, GreenAntz the enclosure looks just fine, maybe better, without wings - builders can just order the naked board, and use PCB offset legs to screw it down. The drawback with this is that you cannot both use the enclosure and screw it down.

So, I am interested in opinions about what people think: for the GreenAntz enclosure, is it better to have the wings or not. Please provide input promptly as Ond will likely be working on the design soon.

If you want to add a pair of wings to hold down that case, the challenging part is how close the USB-C connector is to the corner.
- Maybe consider a design like this where the "backwards 7" side goes around the VGA port and both wings are the same shape.
- Print with the "backwards 7" side face down for best print layer strength and no supports needed.   


Scott

[Zebidee]

Thanks Scott.

I'm concerned about the aesthetics, practicality, structural integrity.

Do the wings look good? Not sure about that. Thinking it may be better without them.

The material choice also becomes more important - "wings" of most 3D printing resins or polymers could break easily. Then you have a broken GreenAntz case with a sharp edge. Aluminium would be nice, tougher, but more expensive.

So, your "backward 7" bracket idea offers some advantages:

- Printed separately from the main case.
- Does not have impact on main design.
- If you don't need them then don't have to use them or even look at them.
- Same bracket design can be used for both sides.
- No material issues, can be made of same 3D printing resin yet be thick, sturdy.
- Not prone to damage.
- Cheap to make/replace.

In terms of practicality, I could have a bag of these "backward7" brackets and throw a couple in with every enclosure.

BTW I checked the screw-hole size on the PCB offset legs - approximately 3.5mm (eyeballed from ruler - I don't have proper calipers). This seems sufficient. Pic attached for reference.


 

[PL1]

I'm concerned about the aesthetics, practicality, structural integrity.

Do the wings look good? Not sure about that. Thinking it may be better without them.

The "backwards 7" design was just a suggestion for retrofitting existing cases.

For better aesthetics, practicality, and structural integrity, you might consider a case design with one top and two interchangable bottoms -- a non-mountable plain bottom and a mountable bottom with legs instead of wings.

That could allow customers to choose between 3 (or 4?) hardware options:
  1. No case - 4 PCB offset legs and 4 machine screws for PCB plus either 4 wood screws or 4 machine screws and 4 threaded inserts.  I'm a big fan of threaded inserts, especially when mounting something to MDF.
  2. Non-mountable case - Hardware to hold the case halves together or will it just snap together?
  3. Mountable case - Hardware to hold the case halves together or will it just snap together? Either 4 wood screws or 4 machine screws and 4 threaded inserts.
  4. Kitchen sink option - One top, two bottoms, and enough hardware to go with any of the three previous options.

Too bad that the connectors are on the long side of the case, otherwise you could have four legs with screw holes, one near each corner and two legs without screw holes in the center of the long sides.
- Some ants have wings, but all ants have six legs.   

If you're worried about the structural strength of the legs, make the bottom of the legs flat and flush with the bottom of the case and possibly add a fillet where the top of the leg meets the side wall of the case.
- As long as the legs are wide and thick enough, there shouldn't be any problems with strength.
- If the case design uses legs that lift the bottom of the case away from the surface it is mounted to, that will greatly weaken the legs.


Scott

[Zebidee]

Whatever I do, it will be simple. I don't want to be burdened with providing countless mountability "options" for imaginary scenarios (nor do customers, dare I say). Especially as the naked board is already very mountable for serious arcade cab builders.

In particular, I want to retain my sanity and not have a storeroom full of enclosure options parts that may be unwanted or become outdated.

Even designing enclosures is a distraction from the main game of making GreenAntz into a better transcoder. I take it seriously but, at the end of the day, it is just a finishing touch. I want to get it right then move on. It needs to do the job, protecting while looking good & tidy, form fitting function.

If an enclosure will mostly be used in a desktop or coffee-table environment, does it really need to be mounted? Maybe I worry too much. I'd like to do some "market research", hear how other people think about it.

So, maybe some "backwards 7" brackets is the compromise. If all else fails, I guess there is always velcro and double-sided tape.

Too bad that the connectors are on the long side of the case, otherwise...

Maybe you're thinking about the old boards. The new v2.2 boards are less than 52mmx60mm, so longside/shortside doesn't matter much.

[Mr. Peabody]

Very nifty device.  Such valiance in our elden age.  I wonder the frequency of adjustment to the pots?  If often....or more than once or twice.....perhaps some holes with shrouds in the mold extending down close to the pots.

[Zebidee]

Thank you.

You should not need to adjust the pots often, if at all.

Values of some parts in the transcoder may vary up to +/- 20%. The pots allow small differences in outputs to be leveled out. With Y Pb Pr, each "component" of the signal affects the others, so they need to be at the right levels to get a properly colour balanced picture.

I calibrate the pots on each unit individually, using an oscilloscope, before sending them out. This "factory" calibration should be good for the vast majority of use cases.

However, your output devices (e.g. video cards) and CRTs also vary considerably.

Eyeballs vary too - every single person sees colours differently. I myself have red-green colour-"blindness" (Deuteranomaly), which affects around 6% of men. Some might confuse this with a superpower, but actually it just means I see colours, mostly red/green, a little more differently to most people. Not that this should matter if I'm using an oscilloscope, but there you have it.

FWIW I see red and green just fine, but they don't stand out against each other as much as they do for the majority of people. Red flowers on a green tree pop out for most people, but for me tend to just disappear unless I look closely. I usually fail the dreaded Ishihara tests (circles of coloured dots with embedded numbers). But then, I seem to see more colour elements in grey than most people and purples seem especially vibrant. So maybe it is a superpower after all

Anyway, without prejudice, the pots are provided to allow you to make your own adjustments.

Even so, you should not need to adjust the pots often. Open it up if you feel you must, then close it again once you are happy. Putting holes in the enclosure would just encourage fiddling.

If you screw up the fiddling, reset each pot to about 45% (bit under half) and that should be about right.

Very nifty device.  Such valiance in our elden age.  I wonder the frequency of adjustment to the pots?  If often....or more than once or twice.....perhaps some holes with shrouds in the mold extending down close to the pots.

[PL1]

Whatever I do, it will be simple.

OK.

Since many builders/makers either have a 3d printer or know someone who does, it seems like the simplest approach is to:

    1. Ship the plain board with PCB mount feet and screws.

    2. Provide a link to files so users can 3d print their own snap together case that has a top with a recessed logo (easier to print face-down with no supports) and their choice of either a mountable or non-mountable bottom.

This way, you don't need to make, stock, handle, or ship case parts that may become excess or outdated.   


Scott

[Zebidee]

    2. Provide a link to files so users can 3d print their own ...

Yes, Scott, pretty much that. Provide a design that they can print. Even better, could just let them design it themselves. Except I wouldn't go around assuming that people have easy access to 3D printers.

I don't want to get bogged down about screw mounting points. I am now regretting having ever raised the idea. *Nobody* has posted here expressing how great screw mount points would be for their projects. I'm taking that level of enthusiasm onboard.

Getting back to the main point: I want to provide a simple/useful/practical/sturdy/attractive enclosure option solution, for a small extra cost, that can be shipped with the main GreenAntz units. Many people have asked for this and I've already designed one. It just needs some finishing touches from Master Ond.

[Austin_MVP]

Received my GreenAntz transcoder recently. Finally got to trying it out today with my SuperStationOne. Going from the SuperStationOne's VGA out to the transcoder to my CRT. Looks great.

I've yet to get my Batocera PC setup with the CRT script, but I'm sure it'll work great.

Thanks!

[Mr. Peabody]

God, I wanna get one just cos it's cool. I don't have a component TV, though. I remember years back you talking about component and vga differed only a little and that getting the...chroma?...correct would give the correct signal.  And what an evolution, especially comparing the original design in 2020 (six years!) to the latest.

Interesting about your color perception. A few/several people in the world see colors where others don't, mainly blue to violet as I recall. My eyes see a little different shade between them....though I don't know whether this comes from genes, as a grade schooler looking at the sun until I couldn't and my eyes watered shut, or the time in high school I whipped liquid detergent and bleach powder into my eye while opening the latter package and sloppily the former, that scored and filmed my eye for at least a day or two. Probably the last.

Speaking of red and green. In your initial thread post and in Austin_MVP's above, the red stands out, the green looks aqua.


@Austin_MVP: that looks Killer. I love newer CRTs for the quality of image. With the correct signal TVs especially, for clarity of image and fabulous convergence and picture linearity.

[Zebidee]

Received my GreenAntz transcoder recently. Finally got to trying it out today with my SuperStationOne. Going from the SuperStationOne's VGA out to the transcoder to my CRT. Looks great.

I've yet to get my Batocera PC setup with the CRT script, but I'm sure it'll work great.

Thanks!

Thank you Sir, so glad you are enjoying it   

Those pics look great! Thank you for sharing   

Hope your Batocera install goes well too. For best results choose negative polarity for the horizontal/vertical sync. More on that soon.

God, I wanna get one just cos it's cool. I don't have a component TV, though.
...
Interesting about your color perception.
...
Speaking of red and green. In your initial thread post and in Austin_MVP's above, the red stands out, the green looks aqua.

Colour is a subjective experience, different for every set of eyeballs and visual cortex. Additionally, there is a huge variation in CRT TV colour output. Finally, to see those pics on this forum there is another camera and more monitors.

Component video further muddies the water because the original analog RGB signal is being converted to Y Pb Pr by the GreenAntz, digitized to Y Cb Cr by the CRT TV's jungle chip, "processed", demodulated, and ultimately converted back into digital RGB then analog RGB again. Each jungle chip also has an assortment of settings for color systems, intensity, balance, tint yada yada. They are all a bit different and tweaking settings can make a big difference.

All that before we even get to CRT gun strength or other electronic maintenance matters.

So, best to set GreenAntz to standard levels using the oscilloscope. Then confirm with eyes against some favourite games with strong colours (e.g. Wonder Boy, Time Pilot).

There are pots you can use if you really must. Each gives you up to around +/- 10-15% or so. Suggest you at least mark positions first. If all else fails, adjusting each pot to around 40-45% of range should be about right. Go crazy, just don't wear them out (they are cermet pots, tougher than average, but nothing lasts forever).

But I suggest looking at the TV itself first, there are so many variables, especially with component video.

Recent improvements to the GreenAntz voltage regulation circuit and video output certainly made all the colours pop a little more. I even had to lower the median/centre value for the Pr (red) attenuation pot in latest GreenAntz v2.1 & v2.2, to keep the "ideal" at about ~45%.

Watch this space! I'm going to post soon about some further work I've been doing to improve the sync handling.

[Ond]

Fine tuning this today. Measure, adjust, print, repeat.

[Zebidee]

We/I appreciate your work and attention to details.

Instead of waiting, I've been busy completely re-vamping the sync circuit. More on that soon.

[Zebidee]

THAT SYNCING FEELING


Summary: Completely re-vamped sync circuit for GreenAntz: "Sync for all occasions".


BACKGROUND

Some people have contacted me recently with sync issues, which boiled down to sync polarity.

One person was using an Nvidia card with it's built-in 320x240p mode, which appears to defaults to a mixed positive/negative. Fortunately this can be altered in the setup (to negative/negative) and seems to have worked for them.

Another was using Batocera setup (cloned) onto a similar PC with an unknown onboard GPU. Many variables in play, but again it seemed the issue was with the sync polarity setup.

These cases are rare (negative/negative sync is more common, or positive/positive), but highlighted to me that GreenAntz sync circuit had an issue with *mixed* sync polarities.

So I set myself to designing a better sync circuit for GreenAntz 2.3+.


STATE OF PLAY

I tested various transcoders with different sync polarity combinations, and prepared this summary table:





Csync "pure" refers to csync input only (VGA pin 13), with no incidental vertical sync (VGA pin 14).

Csync "CRTEMU" refers to composite sync via CRT_emulator software, which does not blank out the Vsync line signal on pin 14. This is not a bug as such, and other software may have the same issues. I did have some success getting GreenAntz to automatically process this csync anyway, but it always came at the cost of not recognising positive polarity sync input (refer table). Otherwise, the only way to make any transcoder work was to disconnect or blank the vsync (GreenAntz has an override switch).

Bitfun uses the Tomi Engdahl sync circuit (more on that below), so it managed to sync with all polarity combos, though it failed on composite input of either kind.

I have a couple of Wakabas. My newer Wakaba (2.3) managed with composite sync input (pure), but failed with csync input via CRTEMU. There is no override switch. It failed on mixed polarity sync input. Mine is a few years old now, there may be newer Wakabas available now.

GreenAntz similarly failed on mixed polarity sync input. Most versions also recognise csync input, though this sometimes requires the override switch (depends on version).

All transcoders worked OK with double negative sync input.

The line at the bottom (highlighted in CYAN) is the new sync circuit I'm developing, which outperforms all of them.


NEW "SYNC FOR ALL OCCASIONS" CIRCUIT


I'm developing a new GreenAntz sync circuit which will be roughly on Tomi Engdahl's (below), but with a few key innovations/improvements.





Firstly, it will work with all sync input polarity permutations, per the original, PLUS composite sync.

Secondly, it will support a sync signal indicator LED, which will only light when a sync signal is present. This will be a more consistent and clear signal indicator than the sync LED on current GreenAntz versions.

Thirdly, it will BLOCK higher frequency signals (VGA, 31khz+) automatically (optional, but on by default). I hope so anyway, because I haven't tested this last part yet

If I can pull this last part off then it will protect TVs from potential damage from higher frequency input. This would be a significant improvement and allow GreenAntz to function similarly to Buttersoft's 15khz dongle, or a JPAC.


PROGRESS


The new basic sync circuit will use more logic gates (4 vs 2 previously), but those four logic gates/comparators can be included in a single chip, the CD74HCT86.

I already had some of these ICs in a SOIC-14 package, which is for SMD (surface mount). That makes it difficult to prototype with, so I've soldered it onto a breakout board, then inserted pins at the provided 2.54m spacing, which is ideal for use with standard breadboard.


   


Then all I had to do was to plug in the various components for testing.





NEARLY COMPLETE

As you can see from below, the circuit works fine and generates correct horizontal and vertical (circled in red) sync pulses.





The circuit has been modified/improved so that it also accepts composite sync input correctly, in addition to all +/- permutations.

The blue sync LED only lights when a horizontal signal is detected.

I've already incorporated the above into ongoing GreenAntz design, both schematic and PCB.

I am still working on a active filter to block VGA 31khz+ signals, but this will require an op-amp. I will have to wait until some parts arrive and I can test further.

In addition to the quad logic and op-amp ICs, I'll also be using one (or two) Schmidt-trigger logic comparator buffers to bring the signals back to a nice square wave after all the filtering.

The new sync circuit will use a bit more space than the old. Part of the challenge is not moving the sync LED, as that would throw Ond's enclosure designs into disarray   

Aiming to include all of these improvements, and the enclosure, included with the next GreenAntz v2.3!