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Post by hydrophilic on Jul 17, 2014 4:49:07 GMT
Here is another option to connect the RGBI output to a monitor/TV using SCART. I've never seen a SCART TV where I've lived, but I hear they were very popular in Europe. I don't know if this should be considered modern, but it is another option. This solution was reported to me by Tero Säärelä. Based on discussions with him, I drew up a circuit diagram and posted it on my website. Here is the page with the circuit and discussion of the adapter. He was also kind enough to send some photos of the working result. Let's see if I can get the here...  To get 16 colors he used the pull-both circuit I published earlier. This means he gets dark yellow instead of true brown. He also reports the display is too dark without adjusting the contrast on his TV. Probably needs smaller resistors in the pull-both circuit. |
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Post by cthulhu on Jul 25, 2014 9:01:02 GMT
Last year I built almost the same cable (thanks hydrophilic for your pull-both circuit!), but I added a switch to have 40 column composite signal on the SCART as well. I didn't put 1K resistors on the +5V line, in my case I seem to not need them, but that it could be just me. What I found to be really usefull was to swap the 1K and 1.2K resistors in the pull-both circuit with 1K variable resistors as with the "default" ones colors was too feeble. That way I could adjust the intensity of each color.
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Post by hydrophilic on Jul 25, 2014 11:28:27 GMT
Nice to hear to about your SCART experience. I used variable resistor for testing too (s-video / vga), and the fixed resistors shown were based on that. Based on your report, and Tero's, it seems SCART in general needs higher voltage (smaller reststor). Although I have no way to determine optimal value myself. Ha ha, if you look at my VGA page, you can see adapter I made for Miro has variable resistor on everything  This is because we could not find reliable info about his VGA adapter. I actually put two resistors on the RGB enable line based on Tero's description of SCART (shown in schematic) to be safe. I thought you could probably get away with just one... glad to hear that you can get away with zero! I guess I should update my webpage to tell people. So you made yours switchable with 40-column? That's cool! I assume you switch in the VIC signal on the composite/sync line in 40-column mode... but how did you drive composite/sync when it was in 80-column mode? |
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Post by cthulhu on Jul 29, 2014 7:43:17 GMT
I assume you switch in the VIC signal on the composite/sync line in 40-column mode... but how did you drive composite/sync when it was in 80-column mode? In 80-column I'm using the (monochrome) composite signal from pin 5 of the RGBI output (connected to pin 20 on the SCART connector) to drive sync. |
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Post by hydrophilic on Jul 29, 2014 10:47:20 GMT
Ah, so that method does work for other people too. Now I have to update my webpage.
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Post by cthulhu on Jul 29, 2014 12:52:47 GMT
Now I have to update my webpage. Sorry for causing extra-work  |
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Post by cthulhu on Jul 29, 2014 13:06:53 GMT
I must add that, while having a single cable for both 80 an 40 column could be really convenient, quality of 40 column signal (composite) is really disappointing.
Of course I'm blaming my lack of skill with soldering irons (I found particularly painful soldering wires to the damn DIN-8 connector's pins !) above anything else, but nonetheless...
Next time I'm planning a dual input - dual output harness, using a SCART connector for 80-column and an S-Video one for 40-column. It will require fiddling with the TV remote or controls to switch from 80 to 40 columns, but video quality should drastically improve.
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Post by hydrophilic on Jul 30, 2014 5:32:21 GMT
Yeah, S-Video is much sharper than composite. But with composite, I don't see any vertical lines that people complain about with 40-column on the C128, so I actually prefer it... reminds me of the old days playing on a C64 at my friend's house using a TV, but he was using the horrible RF signal (thankfully composite is much better than RF).
I don't mind updating the webpage, so thanks again for the feedback.
Edit
Oh, yeah, I hate soldering pins for cables too! I prefer to buy a cable and cut it in half (or cut off one end) whenever I can get one... not sure how easy it would be to find a DIN-8 cable, however.
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Post by cthulhu on Jul 30, 2014 10:57:50 GMT
On a side-note, to anyone who would like to assemble this cable, beware that the DIN-8 male connector you should use is the 262-degrees type, not the 270-degrees one.
I did this mistake myself, and now it's hard to push into the C=128 and probably doesn't make good contact.
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Post by Pyrofer on Apr 29, 2015 19:39:49 GMT
Ok, so I designed and am building my own C128 CGA to RGBS adapter. It's dual input taking both the CGA and VIC outputs from the C128. It's output has RGBS+SVid+audio and it powers itself from the 5v on the video connector. The Schematic is here, s5.postimg.org/yqsx5wf93/v1schematic.pngI've ordered a lot of 10 PCBs and if it works well I might consider selling the assembled units. Comments please! |
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This is because we could not find reliable info about his VGA adapter.
