Component Out - How easy is it to accomplish?

Yeah next time you run into difficulty, you'll be able to refer back to this topic for clues how to fix it.

 

What is "give a F"?

It may look fine on screen for your displays but that doesn't mean dick. I've used one circuit for S-Video only to find on another TV of a similar model it doesn't work at all. If it was published in 1988 it stands to reason that something better has come along. Since you're clearly interested in what is better (or else you wouldn't be bothering with RGB in the first place) logically you should be interested in using a better circuit for a better picture (subjectively speaking). Instead you're defending a circuit in the same way people defend their favorite sport team or favorite beer - fanboy style that is.

You don't appear to have a vested interest in the circuit beyond it is what is used in your hardware. My guess is that you fervently believe in the circuit and can't handle someone with the knowledge telling you that what you believe may be incorrect - that is that the circuit, while appearing to produce good results on screen, isn't the end all be all you felt it was. People enjoy being right and will defend something they believe in strongly even if it is clear they may very well be incorrect.

And it is beyond obvious you have no expertise in this realm. Simply telling the world it is "good enough" is not the makings of a well thought out opinion on a circuit nor does it lend any credibility to the circuit actually being good. I can drive a screw into a wall using a hammer but that doesn't make it a nail.

It would seem so. I can tell you that it works pretty good for the N64 though with Calpis suggesting 25mhz I'll be looking into that for kicks.

 

Its "give a fuck",

I don't have any personal gain to defend this amp and yes I'm not an electronic expert cirquit design wise but other people that are and with which I've spoken with and discussed relative matters, consider it a good option that gets the job done.

So no, I'm not just going to ditch it just because someone thats obviously hypochondriac says its an amateur cirquit just because it doesn't satisfy his obsessive compulsive disorder for perfectionism. Amateur cirquit means dick as long as its not flawed in some serious fucked up way and this one isn't. It could be better yes, but Its not flawed.

 

I was thinking since yesterday that I read this to open a thread about the n64 amp , my pre-modded system has a simplified resistor/transistor amp IIRC and I am not that excited with it's performance... it's time to try something else I think...

 

Not something to worry about now. It's simply knowledge, that may or may not become useful to you later. Never know. Your next tv could hate the mods.

 

Doubt it

 

I forgot about digital video, so this isn't quite true, consoles with HDMI have perfectly square pixels.

http://www.assemblergames.com/forums/showthread.php?35063-Adding-S-Video-to-TG-16-PCE-Duo

http://i1216.photobucket.com/albums/dd379/PCGenjin/cvbs.png?t=1295176022

Thank tomaitheous but note that the resistor values are probably off so it might not be much use.

This is most likely the case with a lot of mods, my TV can handle exceptionally bad signals I created with very little experience.

What kind of distortion?

All TVs from the same region use the same signal levels! Plus the difference between NTSC, NTSC-J and PAL is very very slight. RGB can be thought of as 3x NTSC-J signals with chroma removed and sync moved to a separate wire.

You can't use sync as-is. I think it's a logic level signal but I'm not sure. Assuming it is, you can try using it through a 1.2k resistor which will divide it to the appropriate TV level. The VCE (chip you solder to) may have an issue supplying the meager 4 mA of current, so if you want to be safe you can buffer the signal with a 74AHCT1G126 (or probably any 5V logic buffer) then through the 1.2K.

5 of the 7 components are arranged into a simple textbook amplifier like this: http://tronixstuff.files.wordpress.com/2010/07/1txamp.jpg

Of the 2 remaining components the 75 ohm R choice suggests a misunderstanding of the circuit, and the 10/300 ohm R looks like tweak to get it working.

Even after calling it "the best"?

This is silly, I play via composite 90% of the time.

It has flaws, they just happen to be invisible. If this amplifier were used as an RGB "amp" for another console there's a high chance of the 10 uF capacitor exploding. Does that count?

 

Why not just use Composite Video as the sync source?

Assuming you are connecting it to a RGB enabled TV (rather than a monitor or something) thats a perfectly valid source of sync and should be correct for the TV to use as is.

Also means if you connect to a TV without a RGB enabled scart socket - it would fall back to composite, which is exactly how scart is supposed to work.

use the THS amp + composite video

Or am I missing something?

 

"I forgot about digital video, so this isn't quite true, consoles with HDMI have perfectly square pixels."

Old consoles deserve the next best thing. Clearly defined pixels may look nicer than fuzziness.

"This is most likely the case with a lot of mods, my TV can handle exceptionally bad signals I created with very little experience."

Right. What works for a user and they find safe, should be understood as just that. Nothing more or less. "wrong" doesn't mean unusable, intolerable, or even mediocre. It can be a very entertaining graphics experience.
Us who use our consoles to enjoy are ultimately best served in the real world by how games look.
Either way past a certain point the "right" way begins to have diminishing returns. Eventually one hits quality roadblocks in the console's and/or TV's design.

"What kind of distortion?"

The distortion on setups where composite/etc gets blatant significantly inferior overall sharpness to RGB/etc.

"This is silly, I play via composite 90% of the time."

Many people do. It's often a damn travesty how games look for a large portion of them, relative to what a game's artists drew. Of course for those who don't care/know any better it isn't much of an issue to them.
If anything I regret learning as much as I have. Blissful child ignorance seeing blurred 80s visuals on a CRT without it mattering, was an experience I'll never get back.

 

Some games are designed to look correct over composite, rather than RGB. They are intentionally using the effects of composite.

NES for example. If you RGB mod it, some games do not like right.

 

Yeah part of the problem. One can't have things both ways. Full screen blur means objects that don't use the effects suffer.

An intelligent blurring solution could in theory be more ideal. Except doing that to peak effectiveness, involves tailoring a filter for specific games.

 

It works but using composite instead of composite sync can cause stable checkerboard or vertical lines patterns onscreen. This is particularly visible on Genesis/Megadrive, Mastersystem, NeoGeo and maybe others I haven't come across yet. I've also seen this happening on the DUO-R PCEngine. If you use composite sync you get none of these.

So what. A simple textbook amplifier with modifications can't be suited to work on a pcengine?

I call it the best value for money solution. Simple and small enough that gets the job done on an old console giving excellent visual results.

I meant cirquit design wise. You're being too "perfect" when in practise you'll get very little (if at all) out of it, specially in pcengine's case. Maybe you could use your "perfectionism" to solve the jailbar issue on the pcengine that is visible on both composite and rgb but more on the later due to better sharpness. That would be perfect since no one has done it so far.

No it doesn't. This amp was published as a pcengine specific rgb amp and I never said otherwise.

 

I have only experienced that on the N64 - all other consoles have been fine (as its the way scart is designed to be used, to fall back to composite).

 

If you only used them on crt then yes I agree with you, they are not visible. Use them on an LCD and you'll see them, can't miss them, they are particularly visible on solid backgrounds like the sky in wonderboy in monsterland for example. With composite sync you get clear picture on both types of tvs. Possibly the digital processing an lcd does on the signal makes the extra data in composite that normaly are useless for RGB, appear like this. http://i918.photobucket.com/albums/ad30/gorgyrip/IMG_1533.jpg

 

^ I have experienced it on both my md1 and sms2 machines... when I switched to c-sync the rainbow/checker/wavy artifacts completely disappeared...


edit:

will this work? (provided you feed +5v / GND on the appropriate pins)



Also what is "output enable input" pin on the 74AHCT1G126GW (datasheet link) , do we need it?

 

I don't think that word means what you think it means. At the very least in this context I don't see how Calpis is a hypochondriac.

 

Hypochondriac is someone that is making a big deal over nothing and exagerating. Trust me I know what it means, afterall it is a Greek word.

 

Huh? They can't have it, they're analog. If you recreated the consoles to give them HDMI out, then you'd have to scale the image horizontally to make it look right with square pixels. If you didn't and it were "pixel perfect", video would be scrunched horizontally like most emulators were until recently.

Here is what square pixels looks like without scaling:

Here's how square pixels would look w/ fake scanlines (according to Ootake):


Here's how square pixels would look w/ horizontal stretching to approximate the pixel aspect the PCE is using for this screen, as viewed on a TV (according to Ootake... which is inaccurate in this regard, but you get the idea, it's slightly wider):

(How is this STILL being miscommunicated??) Wrong shouldn't have air quotes, it literally is wrong, and yes it does mean intolerable and mediocre at least. It means that you're lucky if a bad circuit is usable on 1, 2 or 10 TVs because it might not be usable on the 11th. If it doesn't work on the 11th do you call the TV bad? You shouldn't because it's not the TV's fault, it just isn't forgiving of bad signals. A properly constructed circuit will deliver a working signal on ALL working TVs. That's the difference. Doing things the right way isn't a diminishing return until you're shipping many thousands of units and you know exactly where you're skimping. For a modder the costs of a few components are trivial. People are more likely to exercise the law of diminishing returns on their brain energy expended to learn to do things the right way. That's fine when people skimp on their private projects and maybe even offer the circuit to other people for their private projects, but it's a problem when people relentlessly promote and defend and install kludge circuits.

You asked for it so here's a big reply:

"blatant significantly inferior"? It doesn't, look at the comparison video posted earlier. Most people have no objection to composite's sharpness, they object to the video artifacts (which actually is a kind of modulation distortion), and the artifacts can be improved by using a better comb filter, or removed entirely by using S-video.

Sharpness is dependent on bandwidth, the more high frequency content is allowed to pass, the sharper pixels may transition. RGB obviously has the most bandwidth, but S-video was designed to give you the same viewing experience at a significant reduction in chroma bandwidth, and it succeeds with more or less color bleeding. Composite is S-video transmitted on a single wire instead of two; to achieve this luma (which is responsible for the majority of sharpness we see) must also go through a significant reduction in bandwidth so both can fit into the frequency spectrum of a broadcast TV channel (only 6 MHz for NTSC). That said, I don't think the luma bandwidth allotted for composite is insufficient for viewing most PCE(/FC/MKIII/SFC) video... I don't think it's even insufficient for viewing MD (/lowres PS/SAT/N64), you can still make out pixel boundaries with a clean signal.

It's "high resolution" games (480i and up) where you finally cannot make out pixels via composite, they're all blurred together. Even RGB might not have clearly defined pixels in 480i video modes because the TV might not have the bandwidth for it. Also small TVs with poor dot pitches begin to influence the pixels we see. For sharp game pixels we need a very fine dot pitch.

Ironically most current gen games have such complicated graphics that they imitate natural video, the kind composite was designed to compress, so they look really good over composite (apart from small text being illegible and other bad design choices).

This is quite off-topic and complicated but really important: sharp pixels only exist synthetically. They are created by extremely high frequency components present in a signal output from a fast DAC without a "reconstruction filter". In some applications like audio a reconstruction filter is an absolute necessity because you're severely distorting the signal through aliasing without one. Video is the same way if you are viewing natural video like a live TV show or movie on DVD, the goal is to accurately reproduce the original information that was captured by the camera, not distort objects the camera captured by displaying them as distinguishable pixels. Unnatural video from games and computer applications are made up in the digital world so there is no analog smoothness to recreate/aliasing to suppress, (old) video games that aren't meant to imitate real life or playback natural video don't have reconstruction filters and that's why they may have beautifully sharp pixels wherever bandwidth permits. Even though the PCE's main 5.37 MHz pixel clock only theoretically has a bandwidth of 5.37 MHz / 2, the fast transition speed of the PCE's DAC is creating frequency components with significant energy (because it isn't suppressed by a reconstruction filter) up to probably around 100 MHz. When you have a crappy TV with a RGB bandwidth of 5 MHz your pixels aren't very sharp, you're missing 95% of the possible sharpness. A sharp signal requires at least 3x the fundamental frequency (5.37 MHz / 2) at minimum, or preferably 5x, 7x or 9x which would come to under 30 MHz... If you had a HD CRT with over 100 MHz bandwidth you would actually be able to accurately view the PCE's *full* sharpness, but only if you use correct video transmission circuits as I have been advocating. Bad circuits lead to unintentional filtering which means that you may not get the full sharpness that your display is capable of.

Back in 8-bit days artists designed game characters on graph paper and entered them pixel by pixel, I think the artists knew what they were getting into because they had to design around the constraints of RF lol. (Remember the original PCE was RF only.) Today we're still doing injustice to artists' conception since we have limited texture memory and a polygon budget, limited modeling ability, limited animation ability etc etc, I don't think artists are too upset about some video artifacts when everything else had to be compromised.

Not properly. You need to put 75 ohm resistors on the output pins and 100 nF (0.1 uF) or larger ceramic capacitors on the inputs. You should also put the same kind capacitor between "Vs+" / 5V and GND.

I also can't say whether or not the sync signal will work, it's only a hunch that it's digital, it would take quite a bit of work to find out for sure. If it's really an analog signal then you can use a 4 channel amplifier and wire it the same as the RGB lines.

It needs to be connected to VCC / 5 V.

 

right, thanks for the extra components list
isn't evidence that the sync signal is analog since we already pass it through the amp that gtsamour mentions and it works?
Also can you recommend a 4-channel amp suitable for it ? (I am more of a "monkey see - monkey do" person, I can build stuff if someone tells me how...)

 

Digital signals can pass through the amplifier as well, but they may be distorted if they are too large. One reason I believe it's digital (besides sync usually being digital) is because of that circuit, notice how they changed the 10 ohm resistor to 300 ohm on sync (which is dumb because it's not a common value), if it were a TV ready signal it could use the same amplifier.

The THS7374 looks really really good:

http://www.ti.com/product/ths7374

It even allows you to bypass the reconstruction filter I was talking about in the last post, and it has a bandwidth exceeding the frequency components of the PCE's DAC, so you'll get maximally sharp pixels on your display if it's constructed well. Even if you don't use the 4th channel because sync is digital it's still a good buy, they don't have a similar chip in 3 channels.