it1@Isis.MsState.Edu (Tim Tsai) (05/01/91)
I'm looking at the October, 1990 issue of Radio Electronics that has an article on an NTSC-To-RGB converter for ~$100 dollars. The main components of this tiny device are National LM1881N video sync separator and Motorola TDA3330 NTSC to RGB decoder.. Seems to me that going the other way around (RGB-To-NTSC) shouldn't be much more difficult or costly.. Any comments? Are there any specialized chips for this purpose? I'd be interested in a simple "black" box that converts VGA Signal to NTSC. Thanks in advanced.. Tim. -- Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us. <Calvin>
mzenier@polari.UUCP (Mark Zenier) (05/01/91)
In article <it1.673039354@Isis.MsState.Edu> it1@Isis.MsState.Edu (Tim Tsai) writes: > I'm looking at the October, 1990 issue of Radio Electronics that has >an article on an NTSC-To-RGB converter for ~$100 dollars. The main >components of this tiny device are National LM1881N video sync >separator and Motorola TDA3330 NTSC to RGB decoder.. I just built one for a friend. Good quality kit. Now all I have to do is test it. My friend ordered it over the phone and the guy at Harmonic Research said he had sold around a thousand of them. >Seems to me that >going the other way around (RGB-To-NTSC) shouldn't be much more >difficult or costly.. Any comments? Are there any specialized chips >for this purpose? I'd be interested in a simple "black" box that >converts VGA Signal to NTSC. Thanks in advanced.. See either Radio-Electronics December 1989 or for a more complicated board, Circuit Cellar Ink issues #1 and 2. (The CCI project was also available as a kit which I built for the same video nut friend. Not really recommended. Both the quality of the design and the inherent limits of NTSC made the results less than satisfactory.) Remember that NTSC is a system for throwing away information so that the signal will fit in a restricted bandwidth (4.2 Mhz). Ntsc bandwidth limits changes to the color subcarrier to around .8 to 2 MHz (ranging from kosher NTSC to whatever your TV set will handle). The Lumiance is limited to 4.2 Mhz (at best with comb filtering). The best a NTSC signal will handle is 40 columns of text. Thats why the IBM CGA has the 40 and 80 column modes. And if your horizontal scan rate is not 15734 Hz, forget it. Mark Zenier markz@ssc.uucp mzenier@polari.uucp
it1@Isis.MsState.Edu (Tim Tsai) (05/02/91)
mzenier@polari.UUCP (Mark Zenier) writes: [Regarding VGA->NTSC Converter] >I just built one for a friend. Good quality kit. >Now all I have to do is test it. My friend ordered >it over the phone and the guy at Harmonic Research >said he had sold around a thousand of them. I just called Harmonics Research and they do have a VGA->NTSC/S-Video converter in kit form for around $120 (the exact price escaped me). The assembled device is $283. We're probably going to give it a shot. We're primarily concerned with S-Video (our monitor supports it), so the low resolution of NTSC doesn't really matter to us... Thanks to all those who replied.. PS: The number for Harmonics Research is (201) 652-3277.. I'm not affiliated with Harmonics Research except that I think they have a potentially good product at their hands. Tim. -- Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us. <Calvin>