jhs@MITRE-BEDFORD.ARPA (04/08/86)
I still haven't gotten a circuit from my cousin for producing RGB from NTSC etc., but I just got a new Signetics manual and I think the answer lies therein. Reference: Signetics Linear Data and Applications Manual, Vol II, 1985. Page 8-269, data sheet on TDA3563, "NTSC Decoder with RGB Inputs", and Application Note AN156, Page 9-271, "Application of the NTSC Decoder: TDA3563." The Application Note gives a complete schematic and explanation of how to use the decoder. It should be straightforward to build up a working unit, with only a couple of details to figure out. For ST owners, this circuit (Figure 3, p. 9-271) will give the capability of driving the ST color monitor from your VCR with excellent picture quality, or hooking the RGB monitor to a computer or other device which provides only NTSC composite output. For 800XL owners, or others who have a source of both luminance and chroma signals on SEPARATE WIRES, it could be modified trivially to take these two inputs and produce essentially full resolution RGB displays if you have a high-quality RGB monitor lurking about. E.g. 800XL owners planning to upgrade later to the ST family could buy an RGB monitor now, build the circuit and use the RGB monitor with the 800XL with much better image quality than available on a composite monitor, then later use the same monitor with their ST. (You will have to wire up some resistors inside your 800XL to an unused pin of the monitor jack to bring out chroma, but it is easy to do.) I haven't seen the results myself, but I have it on good authority that once you have seen the color image quality you will get on an RGB monitor with this circuit, driven by separate luminance and chroma inputs, you won't ever want to go back to using a TV set or composite monitor! (WARNING: If you drive it with composite, where chroma has been band-limited and mixed with luminance, the image will be only as good as on a good composite monitor.) Anybody needing a copy of the data sheet and application note and ABSOLUTELY UNABLE TO FIND IT LOCALLY may send me a SASE at John H. Sangster 9 Bellevue Road Wellesley Hills, MA 02181. and I will TRY to get a copy to you in a reasonable amount of time. If the response is small there will be no problem but I make no guarantees if I get a flood of requests. NOTE: Your local SIGNETICS rep should be able to get you a copy of the Application Note, or some engineer you know should be able to dig it up at work. Please ask me to copy it only as a last resort. Thanks! -John Sangster jhs@mitre-bedford.arpa ...!ihnp4!linus!mbunix!jhs