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About cwilkson

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    Novi, MI
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    Atari2600 Hardware, teaching electronics, Analog Computing
  1. You have to load the amplifier with something. Try connecting a 75 Ohm resistor from the transistor's emitter to ground and report back here. (from "C-video out" to "RCA GND")
  2. Thanks to you both. It's a pretty exciting idea, and I'd like to get back to it, but life is really busy these days. I will post here in the forums if(/when!) I pull the project off the shelf.
  3. No, the project is mothballed. I have one. It's quite nice. But that one and my backup are the only ones in existence. There just was not enough interest to support the development and I couldn't find help with testing when i needed it. I've considered taking the project out of mothballs a few times over the years, because it offers higher quality and some features that I haven't seen on the other converter projects that are available. But I don't really see the point as everyone seems to be happy with the individual format converters that are available elsewhere. I could be wrong...
  4. The color delay voltage is a poor mans adjustable power supply. The voltage at the "top" end of the 2 diodes will be 5V + (2 * V_FD) ~= 7.3V. The 500k pot allows you to adjust pin 10 (the gate voltages of the internal delay line) from that value down to 0V. The "proper" voltage depends on your particular TIA. You should definitely use a visual tool such as the Video Soft (classic) or CyberTech (better) Color Bars programs to do the adjustment. Or, if you have an oscilloscope or a vectorscope, use that. That's the best possible adjustment. And wait until everything is warmed up. Temperature makes a difference of those delay gates!
  5. I still have most of these available. Someone please save them from the landfill!
  6. Hi all, sorry for the delay. I needed to pull things and sort through them. I will be answering PMs as time permits. Meanwhile....here is a listing. Apologies for the M$ Excel format. Also...I'm in the Detroit area. New Microsoft Excel Worksheet.zip
  7. It's time to unload my magazine hoard. I have a couple of pallets of boxes full of magazines. Many titles & categories. Electronics: Radio Electronics (many going back to the 40's), Popular Electronics, Circuit Cellar, etc... Computers: Byte, Rainbow, Hot Coco, Compute, Run, Family Computing, PC Magazine, Popular Computing, Analog, a few others. I'll try to get some listings up as time permits. I would prefer bulk buys, but if you're looking for particular issues let me know what you need.
  8. That is an L-C filter for the main clock (PHI_2). The orange thing is the inductor. It was only used on early units. Later units don't include it. You should remove the inductor and the stand up capacitor per Atari Service bulletin. Be careful not to damage the other components (C201 and R206). They are under the LC filter. (And you should send that inductor to me for documentation purposes. I think it's marked 330 but I don't know if that's micro- or nano- Henry. )
  9. These files are viewable using GC-Preview. There is a free version available for download from the Graphicode website..
  10. Nice! I really hate it when manufacturers try to protect us from ourselves by hiding or locking out features. And their default settings are always WRONG. I could *never* use my TV for anything critical. No adjustments beyond volume and "theater/game/movie" setting. I'm glad you found the adjustments on yours!
  11. This is due to too much color saturation in the monitor and mismatched black levels in the video signal. In short, the single edge created by BLANK to BLACK transition looks like a colored pixel to the video decoder. Depending on the delay vs. the color burst you'll get blue (close to 180 degrees of phase) or green/brown/gold (close to 0 degrees). Solution: Turn down the color saturation of the TV/monitor. Of course that creates other issues such as washed out colors, but....there are compromises.
  12. Thanks. It was really nice. I literally couldn't see the difference between CyberTech VGA and Stella output on the same monitor. Yes, literally is the right word; the only way to tell which source was active on the monitor was to wiggle the joystick or hit the keyboard. And it was mind boggling that I couldn't find testers. Crazy crazy. If I ever get back to it I will announce it here for sure. Right now I'm bogged down in a new vector arcade PCB project.
  13. It was never produced due to lack of interest. I couldn't believe it. It was ready for beta testing, but no takers. So it sits on a shelf, unused (except by me). As it sits, the only CyberTech mods are VGA, Component, S-video, and Composite. S-video and Composite work with NTSC and PAL (and probably SECAM). Those SCART options could probably be done with the existing hardware, but there would have to be a lot of interest (a lot) for me to pull it out of mothballs. There have been many FPGA versions, of varying quality, over the years. You might be thinking of Cassidy who went on to do the Flashback. (I think that was Cassidy?) If you're doing that, it's trivial because you have open access to all of the internal signals. Plus you can create your own signals specific to the task and whatever format you want. Mine uses the stock TIA outputs and umm....upconverts(?) them to VGA. I don't really have a good word for it. I take what's coming from the TIA, clean it up a lot, standardize the colors, then output it to the world. It's actually got a *negative* conversion loss. It's not trivial at all. In fact, we all thought it was theoretically impossible, even with loss, until I got too much Mt. Dew in me one day and just DID it. But I had thought about how to do it for years before actually trying. I have one of those RGB 7800s. It's pretty nice. But IIRC it only syncs to 15.7kHz. Which rules out using most monitors. And it uses the MARIA/TIA outputs as-is, without compensating for unit to unit variation in the chroma delay. Also, you can't make them anymore. The parts don't exist.
  14. I used the CyberTech VGA, of course. Even after all these years it's still the only one that can do VGA or component video on a 2600, AFAIK. Here are some screenshots. Pitfall II is from a ViewSonic P815 monitor (21") which was my main PC monitor at the time. The video quality is most noticeable in the lack of color bleed around the tree trunks and the red cross. Especially around the trees. It's impossible to do that in NTSC, even with the new CyberTech S-video card. River Raid is from a Commodore 1942 monitor (13"). Someone had asked for a "scan lines" option and wanted to know what it looked like on an Amiga monitor. The option is selectable with a switch on the CyberTech VGA card but could be done using the BW/color switch at power on. These pics show the difference.
  15. Ah. OK. I was excited for a minute. I thought their was a second 2600 with VGA or component outputs. I'll return to lurking now.
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