| Author | Message | ||
     Ryan Rating: N/A |
Today I found a great deal on an oldish (early 90's?) AmPro CRT projector (The kind with 3 seperate gunes). I'm not sure what model I've just purchased (strange, I know, I bought it on my lunch break and can't haul it away until later) but after researching on the internet, it looks like this model might have have refresh rates upwards of 100hz! (someone reported it going to 120, which I didn't think possible for a CRT, but I know next to nothing on the topic). So here's the problem... input... check out this picture I found on an ebay auction http://images.auctionworks.com/hi/46/46038/amproports.jpg That's what the back of mine looks like. S-Video, composite BNC, and RGB BNC inputs. These inputs are replacable, but the company went under so the chances of me getting a VGA in an slim to none. I know that there are older video cards out there with this type of BNC RGB connector (for old Sun 21 inch monitors and what not) but forget about good 3D then. Any ideas as to how one could make this projector useful for D3D and OpenGL stereo fun (or useful for anything, really)? | ||
| Andreas Schulz Rating: N/A |
See e.g. http://www.hut.fi/Misc/Electronics/circuits/vga2rgbs.html for a plan of a VGA-to-RGB (with C-Sync) adaptor (DIY). | ||
| Anonymous Rating: N/A |
VGA->RGB is easy, try Barco for conversion cables if you can't/don't wanna DIY. 120+Hz is no easy for newer CRT's, depending on the specs. | ||
| Alexander Oest Rating: N/A |
Ryan, Have a look at www.avsforum.com - see under CRT projectors Whatever problem you might encounter with the projector, there's a good chance it has been discussed - an maybe even solved - here. Btw, if you only have three BNC inputs, it sounds like you've got sync-on-green. But there's a circuit layout for that too, somewhere at Tomi Engdahl's site (the one Andreas' link points to). Alex | ||
| Ryan Rating: N/A |
Thanks for the info guys, I'll be sure to update you on my progress. | ||
| Ryan Rating: N/A |
Well, it looks like I have an AmPro 2600D on my hands. (I'm kinda bummed, the 2600G has a higher scan rate). I'm not quite sure about one thing here... quick specs... (btw, thanks Alex for pointing me to the AVS forum, its been a lot of help!) Horz: 15-64kHz, Vert: 40-150 Hz, and I think about 1400x1050 So my max refresh rate would be 64khz, correct? | ||
| Alexander Oest Rating: N/A |
No, the 64 Khz is the *horizontal* frequency. It is sort of an overall specification within which you can use different combinations of refres rates and resolution. There's a trade-off between the two: the higher res, the lower refresh rate and vice versa. I saw this formula for calculating the "envelope" of the projector: nl*vf*1.1=hf where nl=the number of lines, vf is the vertical frequency, and hf=the horizontal frequency I belive this formula to be reasonnable - it fits with the on-screen information on my BarcoGraphics800 Say you want to know the max resolution for a given refresh rate. Then isolate nl: nl=hf/(vf*1.1) So if your question is: "How high a resolution can I run in 100 Hz vertical refresh"? The answer is: 64000/(100*1.1) = around 580 lines - which translates into a little bit below 800x600. There might be a good chance that the projector can go a bit higher than the specifications, meaning that you'll be able to play games in 800X600 at 100Hz. (going way above specs might damage the projector, though). Forgetting formulas and just looking at my projector's on-screen figures, I got the following information that might be more directly useful to you: 800x600@100Hz~64,5 KHz 640x480@120Hz~62,5 Khz If your projector maxes out at around 64 Khz, these are the resolutions I'd try. Choose for yourself according to your sensitivity to flicker. Personally, I'm running at 100 Hz, and I don't see flicker. How much did you pay for the projector, btw? Alex | ||
| Ryan Rating: N/A |
Thanks for the info. That is, actually, exactly what I was looking for. I agree that 100Hz is usually fine, but I am pretty sensative to the flicker. I really just want the most "solid" effect possible. I have a few VR ideas I'd like to experiment with (If I can actually get the @!$# thing working). I know that one screen is a very far cry from a CAVE, but for a garage project, I think it has quite a lot of potential. Have experimented with stereo 3D on your projector much? $45  | ||
| Alexander Oest Rating: N/A |
Yes, I started the stereo projection experiments as part of my Ph.D.-project - but it turned out to be more time consuming than I expected. Too fascinating to leave. You can read more about it at: http://stereoscopy.cti.dtu.dk/ My problem with the CRT projector is that it demands too much adjustment. And I only use it a couple of times a month (I have the setup at work, not at home). So every time I use it, I have to do a bit of adjustment. Your projector might turn out to be less sensitive than mine, though. Fourty-five dollars! That's... well... fair enough ;-) I paid around the equivalent of US$500 for mine. Sure, it has better specs than yours, but still, it sounds like you've made a pretty good deal. Any luck getting it working yet? Alex | ||
| Ryan Rating: N/A |
Yeah, I've finally managed to get a picture. It has a strange wobble at the top, but I'm still waiting on my VGA to RGB cable to make the final judgement. In widescreen, the wobble is confined to the upper black area, so basically, its perfect. Its giving me quite a few headaches, though. Sometimes I'll have to fiddle with it for an hour before I've got a bright usable picture (and I haven't been able to focus it well at all). I'm going to check out an Electrohome ECP today. If it works well, I might trade up. |
