8 bit guy is talking Intellivision again

[rietveld]

 

 

 

[+nanochess]

I saw it and I was amazed to see I came to the end of the video without feeling the time lapsed.

[JohnPCAE]

I wanted to scream, "Noooooo!" when I saw where he mounted his composite outputs. Mine was much cleaner:

 

https://oshpark.com/shared_projects/T4uK2inN

 

[spacecadet]

He was an early inspiration for me to get back into retro stuff (not to mention start a YouTube channel) so I don't like to criticize, but sometimes he does or says stuff that just makes me wonder if he even wanted to make the video in question. I feel like he should have taken a little more time with this video - from not figuring out why the RF modulator was still required to not waiting a little longer for a better mounting solution for the composite board - and it seems obvious that it's because he's just not a fan of the Intellivision. He comments several times about how much he hates the controllers, and about how graphically limited the system is. I know from past videos that this is not the system he grew up with, and he seems to have not really taken to it as an adult either.

Edited November 13, 2019 by spacecadet

[rietveld]

3 hours ago, JohnPCAE said:

I wanted to scream, "Noooooo!" when I saw where he mounted his composite outputs. Mine was much cleaner:

 

https://oshpark.com/shared_projects/T4uK2inN

 

Yours looks great. It looks factory installed 

[Zendocon]

I had just tuned into the video last night where he repaired a Music Synthesizer.  I know mine needs fixing, but I never got around to it because it didn't seem worth it just for Melody Blaster.  Maybe if I hack that ROM and change the music, it might be worth another go.

[Sinjinhawke]

Do you have to make that composite board yourself?  Anyone sell those things? Seems like it’s something I might like to try as a project one day.  

[JohnPCAE]

46 minutes ago, Sinjinhawke said:

Do you have to make that composite board yourself?  Anyone sell those things? Seems like it’s something I might like to try as a project one day.  

I designed that board layout myself specifically to fit in the Inty II. It has the same circuit as the one from Turkey. As far as I know, no one else is selling them, so it's DIY.

 

Black connector: https://www.mouser.com/ProductDetail/Switchcraft/PJRAN1X1U01AUX?qs=sGAEpiMZZMv0W4pxf2HiV7sv6uhfrItvDW4M8xvx2XY%3D

Yellow connector: https://www.mouser.com/ProductDetail/Switchcraft/PJRAN1X1U04AU?qs=sGAEpiMZZMv0W4pxf2HiV7sv6uhfrItvBsNHR2KsS%2BQ%3D

Resistors are all 6.3mm 1/4W 1% (typically Yageo)

100uF MLCC Capacitors: https://www.mouser.com/ProductDetail/TDK/FG20X5R0J107MRT06?qs=sGAEpiMZZMvsSlwiRhF8qjQUafaa8S5xxY5jaNk54ifokfPwqQzMNg%3D%3D

100pF ceramic/MLCC Capacitor: https://www.mouser.com/Passive-Components/Capacitors/Ceramic-Capacitors/_/N-5g8m?P=1z0x7xgZ1z0z7l5Z1z0wljoZ1z0wpn9Z1z0x6fr

Transistors: https://www.mouser.com/ProductDetail/Central-Semiconductor/2N3904?qs=sGAEpiMZZMshyDBzk1%2FWiw99kSkYzPxmf7NzGOknJzA%3D

 

The TDK 100uF capacitors I used are to be discontinued but Mouser has lots in stock. Any of these should do, though: https://www.mouser.com/Passive-Components/Capacitors/MLCCs/_/N-bw5rv?P=1z0z7l5Z1z0wrkm

Edited November 13, 2019 by JohnPCAE

[+-^CrossBow^-]

There are several ways to get premade boards and that is what I usually do. Although I have to admit that the results the 8-bit guy got from his Intelly 2 looked good on his CRT, but he was getting lots of noise and color issues that can be seen from his video capture. And those same issues are seen on modern displays as well. At least from the Intelly 2 those are the results I got. So I really don't think that the Intelly 2 is a good candidate for composite mods. The early 2609 models on the other hand can look really good with a composite AV mod in place.

 

Here are some pre-made boards off ebay:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=intellivision+av&_sacat=0

 

And here are the premade kits from Retrofixes: (I've used these a few times but I do prefer the results I get from the boards from the guy in Turkey).

https://store.retrofixes.com/products/intellivision-composite-upgrade-amp-kit-coming-soon?_pos=1&_sid=b8f605627&_ss=r

 

Also I watched the video but David didn't show exactly where he was attaching everything from to his made up board etc? Far as I know, on the Intelly 2 you still get the video and audio from the inputs going into the RF modulator box and grab the +5 and ground from wherever you find it that is convenient off the board.

[ChildOfCv]

37 minutes ago, Sinjinhawke said:

Do you have to make that composite board yourself?  Anyone sell those things? Seems like it’s something I might like to try as a project one day.  

Honestly, I'd suggest using an op-amp circuit instead.  It uses two common emitter amps because each one inverts the signal so you need them in pairs, and the output stage pulls a punishing amount of power through the transistor in order to achieve the 75 ohm impedance with acceptable gain.  That transistor must get hot.

 

An op-amp circuit is easier to build and would run a lot cooler.  As a bonus, it could be designed to work with potentiometers to dial in the gain.

 

As a final note, the intvII has diodes on the video line to allow for external video from the cartridge port that act as current sinks.  So to remove the RF adapter, you need to place a pull-up resistor to +5V on pin 1 so that there is still something to sink.  Then you can worry about the mod circuit itself.

[+-^CrossBow^-]

2 minutes ago, ChildOfCv said:

Honestly, I'd suggest using an op-amp circuit instead.  It uses two common emitter amps because each one inverts the signal so you need them in pairs, and the output stage pulls a punishing amount of power through the transistor in order to achieve the 75 ohm impedance with acceptable gain.  That transistor must get hot.

 

An op-amp circuit is easier to build and would run a lot cooler.  As a bonus, it could be designed to work with potentiometers to dial in the gain.

 

As a final note, the intvII has diodes on the video line to allow for external video from the cartridge port that act as current sinks.  So to remove the RF adapter, you need to place a pull-up resistor to +5V on pin 1 so that there is still something to sink.  Then you can worry about the mod circuit itself.

I've installed several versions of this kit and haven't noticed the tranny getting hot at all. Only talking +5 here not +12 like what is used on the old Ben Heck CV composite mod.

 

[ChildOfCv]

Just now, -^CrossBow^- said:

I've installed several versions of this kit and haven't noticed the tranny getting hot at all. Only talking +5 here not +12 like what is used on the old Ben Heck CV composite mod.

 

Interesting.  In the transistor's active region, it would need to pull several 10s of milliamps at least in order to give a good cushion for the signal.  Couple that with the voltage drop across the transistor itself, and I would expect high milliwatts of power.  Maybe it only sits just barely enough in the active region to get the needed voltage swing without clipping.

 

But anyway, the op-amp would still be simpler

[+-^CrossBow^-]

What would be nice is if something along the lines of a video encoder replacement would be done similar to the UAV to provide a clean consistent composite and s-video output. I know here are RGB solutions, but I think good clean composite and s-video is more than enough for most older consoles. 

 

[Sinjinhawke]

35 minutes ago, -^CrossBow^- said:

I really don't think that the Intelly 2 is a good candidate for composite mods. The early 2609 models on the other hand can look really good with a composite AV mod in place.

I also have the 2609 model so it’s good to know which one has the better results.  Thanks. 

[+-^CrossBow^-]

29 minutes ago, ChildOfCv said:

Interesting.  In the transistor's active region, it would need to pull several 10s of milliamps at least in order to give a good cushion for the signal.  Couple that with the voltage drop across the transistor itself, and I would expect high milliwatts of power.  Maybe it only sits just barely enough in the active region to get the needed voltage swing without clipping.

 

But anyway, the op-amp would still be simpler

The main problem with anything that requires trimmers to dial in, is that it isn't a good solution for those that provide services to modify consoles for others. Because what I dial in to look good on my AV setup, may not work well for the client. Most of my clients are not the tinkering types. They just want to plug in the console to AV inputs of whatever they've chosen to have and get a picture they expect. This is one of the reasons I'm not able to get much interest in offering the Magic Knight AV boards on the 7800. It produces really good s-video when you dial it in, but again,...it has to be adjusted to your AV display setup to get good results. 

 

But it does surprise me that more consistent results is such a challenge in regards to the Intelly 2609 vs later models. I've not done a composite mod to an Intelly III or Super Pro so I don't know the results from those.

[ChildOfCv]

2 hours ago, -^CrossBow^- said:

What would be nice is if something along the lines of a video encoder replacement would be done similar to the UAV to provide a clean consistent composite and s-video output. I know here are RGB solutions, but I think good clean composite and s-video is more than enough for most older consoles.

Well, actually, it would be pretty easy to output the signal as digital RGB by programming a small ROM chip.  The AY color processor just takes a clock input to know when the next pixel is being generated, and otherwise it takes a 5-bit color/sync input and creates a signal output suitable for a resistor ladder DAC.  Have a ROM chip instead output a 3:3:2 value for analog RGB, or output digital values for DVI/HDMI.  If you insist on YPbPr, you could even program the ROM for that.  Maybe I'll toss that idea on my (already enormous) bucket list

 

Anyway, I think the key to consistent composite output is to make sure your sync tips are the proper voltage levels.  Regardless of what's being displayed, the sync signals stay the same.  So I bet that's what the AGC circuitry keys on for deciding how much the signal needs to be massaged, with small consideration if that pushes the p-p voltage too high (>1.4V).  The proper video signal is 0V porch, -0.4V sync tip, and up to 1V luma.  The color subcarrier can be up to 0.4Vp-p at full saturation.  The color AGC circuit may separately adjust the separated color signal to make sure it fits that parameter, so if you don't mix it in properly it may look either washed out or else obnoxiously vivid.  One last note is that engineered devices like VCRs have 470uF output coupling capacitors, so the chincy caps used in almost every AV mod are a bit of a joke.

 

That is to say that the AY chip may not need a digital replacement for analog composite output.  All it needs is accurate resistors, feeding into a near-infinite impedance voltage follower (like an op-amp :P)  One could buy those ultra-accurate resistors that have 3 value bands and 1% or less tolerance, and see if they improve the visuals.

 

2 hours ago, -^CrossBow^- said:

The main problem with anything that requires trimmers to dial in, is that it isn't a good solution for those that provide services to modify consoles for others. Because what I dial in to look good on my AV setup, may not work well for the client. Most of my clients are not the tinkering types. They just want to plug in the console to AV inputs of whatever they've chosen to have and get a picture they expect. This is one of the reasons I'm not able to get much interest in offering the Magic Knight AV boards on the 7800. It produces really good s-video when you dial it in, but again,...it has to be adjusted to your AV display setup to get good results. 

Well, the main reason to begin with a pot is that I don't know the actual gain needed, without painstaking analysis that has to take the RF modulator into account, and would probably make a mistake anyway.  Instead, I'd tune it to "a" system in hand and call that the calibration point.  Then if I were to make the op-amp circuit for sale, I'd tune it for the theoretical gain it's supposed to have, and ship it out.  If the customer feels a need to tinker after that, then so be it.

[mr_me]

3 hours ago, -^CrossBow^- said:

The main problem with anything that requires trimmers to dial in, is that it isn't a good solution for those that provide services to modify consoles for others. Because what I dial in to look good on my AV setup, may not work well for the client. Most of my clients are not the tinkering types. They just want to plug in the console to AV inputs of whatever they've chosen to have and get a picture they expect. This is one of the reasons I'm not able to get much interest in offering the Magic Knight AV boards on the 7800. It produces really good s-video when you dial it in, but again,...it has to be adjusted to your AV display setup to get good results. 

 

But it does surprise me that more consistent results is such a challenge in regards to the Intelly 2609 vs later models. I've not done a composite mod to an Intelly III or Super Pro so I don't know the results from those.

If you make the dial externally accessible, it might be okay for your clients.  The black and silver INTV Intellivisions use the same design as the original Intellivisions.  The Intellivision II has the same graphics chips as the 2609.  The difference has to be what comes after the ay-3-8915 chip.

 

43 minutes ago, ChildOfCv said:

Well, actually, it would be pretty easy to output the signal as digital RGB by programming a small ROM chip.  The AY color processor just takes a clock input to know when the next pixel is being generated, and otherwise it takes a 5-bit color/sync input and creates a signal output suitable for a resistor ladder DAC.  Have a ROM chip instead output a 3:3:2 value for analog RGB

Someone is working on one here.

https://atariage.com/forums/topic/284806-intellivision-ntsc-rgb-mod-design-help/?do=findComment&comment=4220636

 

Edited November 13, 2019 by mr_me

[ChildOfCv]

59 minutes ago, mr_me said:

Someone is working on one here.

THAT GUY STOLE MY IDEA I JUST HAD!

[+Lathe26]

It sounds like that RGB project is on hold for a bit, based on the last post.

[ChildOfCv]

33 minutes ago, Lathe26 said:

It sounds like that RGB project is on hold for a bit, based on the last post.

Hmmm.  That's a bummer.  Well, he also mentioned a potential issue with the graphics processor replacement in an earlier post too:  External cartridge video.  He's not quite correct on how it works though.  The Intv and IntvII implement that by injecting the video at the very end, not even involving the color processor chip or its external video pin.  IntvII adds an enable input that even works to block out the video from the color processor.  So a digital solution would either have the caveat that cartridge/expansion port video doesn't work anymore, or it would need to provide an encoder for external video on that line and a multiplexer to choose between sources.

[+Lathe26]

22 minutes ago, ChildOfCv said:

Hmmm.  That's a bummer.  Well, he also mentioned a potential issue with the graphics processor replacement in an earlier post too:  External cartridge video.  He's not quite correct on how it works though.  The Intv and IntvII implement that by injecting the video at the very end, not even involving the color processor chip or its external video pin.  IntvII adds an enable input that even works to block out the video from the color processor.  So a digital solution would either have the caveat that cartridge/expansion port video doesn't work anymore, or it would need to provide an encoder for external video on that line and a multiplexer to choose between sources.

Regarding external video, it is a bummer that it is tricky to support external video input, if at all.  Fortunately, there are only 2 devices that use it:

• Keyboard Component on the original video input pin.
• System Changer via a different video input pin.

I don't think omitting support for these 2 devices is a big deal since:

• It would be difficult to connect new cables for an Intellivision connected to a Keyboard Component (the KC's plastic gets in the way).  Also, KCs are rare so only some collectors are affected.
• System Changers are only compatible with the Inty II or modified original Intellivisions.  Since this just adds Atari 2600 support, most collectors buy one, try it out for a while, and place it on a shelf.  If they want to play Atari games on a regular basis, they probably keep a real Atari hooked rather than fiddling with connecting/unconnecting the System Changer.  I might be making assumptions about other folks here.

I'd be happy with RGB or HDMI support, even if those 2 devices were incompatible.