Well, this one will be in a rare spot for me since I rarely post anything related to video.
I have a very urging idea that I'd like to pursue. The idea is to convert a normal television to use component inputs. I understand that there are points in my tv that are R-Y B-Y and G-Y. Also, there's the common Y point, and syncs of course. These are very easy to access right near their chroma/luma/sync chip. I've done some studying in the area of how component video information works. It seems relatively simple, using differential information to reduce the need for bandwidth. I'm thinking it wouldn't really be that difficult to make a normal tv use a 480i signal. It already has S-Video and composite as usual. The only thing I'm worried about is the sync, I'm not sure if the sync in a 480i system is acceptable to my tv.
I got the tv for free and I'm not worried about anything happening to it really. It was dead when I got it, and I repaired it(smps problems.)
Any ideas from anyone more knowledgeable with this area?
I have a very urging idea that I'd like to pursue. The idea is to convert a normal television to use component inputs. I understand that there are points in my tv that are R-Y B-Y and G-Y. Also, there's the common Y point, and syncs of course. These are very easy to access right near their chroma/luma/sync chip. I've done some studying in the area of how component video information works. It seems relatively simple, using differential information to reduce the need for bandwidth. I'm thinking it wouldn't really be that difficult to make a normal tv use a 480i signal. It already has S-Video and composite as usual. The only thing I'm worried about is the sync, I'm not sure if the sync in a 480i system is acceptable to my tv.
I got the tv for free and I'm not worried about anything happening to it really. It was dead when I got it, and I repaired it(smps problems.)
Any ideas from anyone more knowledgeable with this area?
Hmm... thats an interesting idea, cant help you with it though...
I do have a question similar - is there anyway to add S-video to a tv that only has composite (no not with a svideo to composite adapter, that will just mix the Y and C, so its useless) I just really hate the combing I get on the lower end tvs at home when I have a PC connected to it.
I do have a question similar - is there anyway to add S-video to a tv that only has composite (no not with a svideo to composite adapter, that will just mix the Y and C, so its useless) I just really hate the combing I get on the lower end tvs at home when I have a PC connected to it.
Well, as far as adding S-video, I don't think that'd be hard either. Of course, I know that the uppers of diyaudio don't like talk of tv modifications because the dangers involved.
Anyway, I know that all television sets decode Y and C from the composide AM signal coming on the line, as they do RGB and sync and everything; so there are definitely traces on the board carrying these discrete signals. I would imagine that in many circumstances, these traces could be cut and new signals injected into the circuitry, as long as the original biases and coupling strategies are still maintained. It is important that the original amplitudes are maintained of course. So therefore, one would have to do some research into the workings of the set before hand and make absolutely sure that he isn't going to mess anything up, including himself.
This is definitely area for you if you've got experience working on television sets in the past, but certainly not a good idea if you don't know much about electronics.
Anyway, I know that all television sets decode Y and C from the composide AM signal coming on the line, as they do RGB and sync and everything; so there are definitely traces on the board carrying these discrete signals. I would imagine that in many circumstances, these traces could be cut and new signals injected into the circuitry, as long as the original biases and coupling strategies are still maintained. It is important that the original amplitudes are maintained of course. So therefore, one would have to do some research into the workings of the set before hand and make absolutely sure that he isn't going to mess anything up, including himself.
This is definitely area for you if you've got experience working on television sets in the past, but certainly not a good idea if you don't know much about electronics.
component video
To the best of my knowledge it would be a chore
first you have to sync the horizontal and verticle scan rates of the deflection circuits to the source ........ ughh (
the component signal is composed of y , r-y and b-y , the green is produced from the jungle ic ( determines the propable green levels )
most older sets i have seen have red , blue , green pins directlly from the jungle ic or R-Y , B-Y , G-Y going to the crt board
Jeff
To the best of my knowledge it would be a chore
first you have to sync the horizontal and verticle scan rates of the deflection circuits to the source ........ ughh (
the component signal is composed of y , r-y and b-y , the green is produced from the jungle ic ( determines the propable green levels )
most older sets i have seen have red , blue , green pins directlly from the jungle ic or R-Y , B-Y , G-Y going to the crt board
Jeff
I looked at the service sheet on my tv, yes, there are of course R-Y, B-Y, and G-Y off the jungle chip, and the H and V sync outputs.
I can't see it very difficult making a circuit to mathematically derive the G-Y from the three component lines by using fast opamps. Logically, one could sum the B-Y and R-Y, and then take the difference between this sum and the total Y. Thus, whatever Y is left over is G-Y information.
After that's done, we have RGB signals. Next, a sync separator would be needed. That is easy to implement with an LM1881 or similar IC.
Perhaps there's a little more to obtaining a G-Y signal than I thought, any truths to this I should know?
I can't see it very difficult making a circuit to mathematically derive the G-Y from the three component lines by using fast opamps. Logically, one could sum the B-Y and R-Y, and then take the difference between this sum and the total Y. Thus, whatever Y is left over is G-Y information.
After that's done, we have RGB signals. Next, a sync separator would be needed. That is easy to implement with an LM1881 or similar IC.
Perhaps there's a little more to obtaining a G-Y signal than I thought, any truths to this I should know?
Yes I have been doing some reading on the values of everything in the signal.
I believe it won't be that hard to adjust the amount gain and attenuation in the signal recorver circuits in order to get good color.
I believe it won't be that hard to adjust the amount gain and attenuation in the signal recorver circuits in order to get good color.
component to rgb converter schematic
Silicon Chip Online has an article about a diy component to rgb converter that looks fairly straightforward. I can't find my link, so you will have to google it if you are interested.
Michael
Silicon Chip Online has an article about a diy component to rgb converter that looks fairly straightforward. I can't find my link, so you will have to google it if you are interested.
Michael
Hi Duo.
Are you still working on this?
I just made an RGB to component converter over the weekend using a couple of AD8056s and it works pretty well. The theory around the converter is pretty simple, though I did have a few issues with the Y component and ended up using a Y output that was available for S-video. Adding the Cr and Cb components resulted in a very good colour picture.
Anyway, let me know if you are still interested and I can go into more detail.
Cheers,
Stu
Are you still working on this?
I just made an RGB to component converter over the weekend using a couple of AD8056s and it works pretty well. The theory around the converter is pretty simple, though I did have a few issues with the Y component and ended up using a Y output that was available for S-video. Adding the Cr and Cb components resulted in a very good colour picture.
Anyway, let me know if you are still interested and I can go into more detail.
Cheers,
Stu
Hi there, yes I'm still interested in doing what I thought earlier.
Though, I'm making a component to RGB converter, not the other way around.
My intention is to modify a television to accept RGB directly, instead of just composite, RF, and S-video.
Though, I'm making a component to RGB converter, not the other way around.
My intention is to modify a television to accept RGB directly, instead of just composite, RF, and S-video.
Sorry. After posting I realised you were doing the reverse of what I did, but I did manage to find a circuit for what you're doing too. These links were hard to find, and in fact if you go to the main page and try to find them, it asks you to pay. I don't know why they're visible, but I'd recommend saving the page(s) while you can, cos they might not be there tomorrow...
Component to RGB
http://www.siliconchip.com.au/cms/A_101537/article.html
RGB to component
http://www.siliconchip.com.au/cms/A_102648/article.html
Good luck! I'd love to know if you get it to work.
Cheers,
Stu
Component to RGB
http://www.siliconchip.com.au/cms/A_101537/article.html
RGB to component
http://www.siliconchip.com.au/cms/A_102648/article.html
Good luck! I'd love to know if you get it to work.
Cheers,
Stu
So bizarre.... those links worked when I posted them, then they only offered the first part of the page. If you've any problems getting the full page, let me know. I saved it. I did find that if it doesn't load completely, if you copy the first sentence of something and put it into Google, it finds the page (exactly the same link), but it's the <b>complete</b> page. Go figure...
Hey Irishstu,
Any chance you could provide the full view of the two links you posted?
Thanks!
Any chance you could provide the full view of the two links you posted?
Thanks!
irishstu said:
Hey diytwice. Have you tried copying and pasting the first intro paragraph into google?(starts with "Does your TV have RGB..." for the first link and "What- no RGB inputs on your TV..." for the second one) I've realised it works every time. I'm a little reluctant to post the whole pages here, as I'm sure it's a little bit too obvious a violation of copyright laws.
That said, if you still can't get the whole page to show, maybe you could tell me your email address and I'll send it to you (by the way, that is in no way a ploy to spam you).
Let me know how you get on.
Cheers,
Stu.
That said, if you still can't get the whole page to show, maybe you could tell me your email address and I'll send it to you (by the way, that is in no way a ploy to spam you).
Let me know how you get on.
Cheers,
Stu.
From my experience with TV's, I believe that the RGB/video conversion is the least of your problems: Although PC monitors are made to utilize varying refresh rates (i.e., variable scan rates), garden-variety televisions are not. TV's derive their high voltage supplies for the CRT anode from the horizontal output (flyback) transformer. This circuit supplies many other voltages, as well. Since this is THE hardest-working section of a TV, it is optimized for the greatest efficiency at the standard horizontal-frequency of the signal being received (NTSC - in the USA - is 15,750 Hz, for a refresh-rate of 30 interlaced frames per second). Changing the horizontal frequency could (very likely) change the derived-voltages unacceptably {although CRT anodes are (typically) between 25KV and 35KV, depending on the set, they are supposed to hold within 1KV of a specified value}.- Status
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