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#1
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CRT circuitry
I bought a tiny little 5.5" B/W TV set, and I thought it would be an
interesting thing to do to take the tube and try and build myself a little computer monitor - nothing fancy, just a device to take TTL horizontal and vertical sync signals and a video signal and give me a couple of hundreds of lines of picture at 50Hz. So I've been surfing around now for a while to find some information on the subject, and it's been very informative. But even though I have now got a general familiarity with the workings of a CRT, I have not been able to find anyone who has built any CRT control circuitry and written about it on the web. It doesn't seem at all impossible though. So does anyone have any suggestions? Any websites with detailed information that is not completely over the head of a beginner? I don't know much at all about analog electronics, being mostly a computer guy. Or does anyone have enough knowledge to offer an example layout of such a circuit for me to try? I'm grateful for any help at all! Bjarni |
#2
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"Bjarni Juliusson" wrote in message ... I bought a tiny little 5.5" B/W TV set, and I thought it would be an interesting thing to do to take the tube and try and build myself a little computer monitor - nothing fancy, just a device to take TTL horizontal and vertical sync signals and a video signal and give me a couple of hundreds of lines of picture at 50Hz. So I've been surfing around now for a while to find some information on the subject, and it's been very informative. But even though I have now got a general familiarity with the workings of a CRT, I have not been able to find anyone who has built any CRT control circuitry and written about it on the web. It doesn't seem at all impossible though. So does anyone have any suggestions? Any websites with detailed information that is not completely over the head of a beginner? I don't know much at all about analog electronics, being mostly a computer guy. Or does anyone have enough knowledge to offer an example layout of such a circuit for me to try? I'm grateful for any help at all! Bjarni Quite an undertaking. My first thought is, "be careful" I am guessing the anode voltage on that tube is 3 to 5Kv and will be present even with no power is applied. Learn how to discharge the tube safely. If you are nervous at all doing it, then you shouldn't be doing it, especially alone. Use the, One hand in the pocket rule, Have a qualified tech demonstrate it for you. Learn and understand where the high voltage is located on the circuit board and be conscious of it when fiddling with the circuit when it is live. Secondly, the deflection circuits are not designed to run at typical computer monitor frequencies. This might prove to be difficult. If you are going to redesign the deflection circuits and have a limited knowledge of electronics then, well, you have a long road ahead of you. Not trying to be discouraging, whether you successful or not you will certainly learn something. But do be careful. |
#3
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DBLEXPOSURE wrote:
Quite an undertaking. My first thought is, "be careful" I am guessing the anode voltage on that tube is 3 to 5Kv and will be present even with no power is applied. Learn how to discharge the tube safely. If you are nervous at all doing it, then you shouldn't be doing it, especially alone. Use the, One hand in the pocket rule, Have a qualified tech demonstrate it for you. Learn and understand where the high voltage is located on the circuit board and be conscious of it when fiddling with the circuit when it is live. Check and double check. Don't worry about my safety. Secondly, the deflection circuits are not designed to run at typical computer monitor frequencies. This might prove to be difficult. Which is why I decided to go with a resolution close to the original TV resolution, as I mentioned in the original post. If I can get 256 lines at 50Hz, I'll be very happy. If you are going to redesign the deflection circuits and have a limited knowledge of electronics then, well, you have a long road ahead of you. It just so happens I found this: http://www.hanssummers.com/electroni...trumanalyser2/ I found a small B/W junk TV/radio/cassette recorder, and when I looked inside it had a very conspicuous chip labeled AN5151, so I googled for datasheets. What I found was the site above. The guy (Hans) has done precisely what I want to do: he took a small B/W TV with an AN5151 chip in it and turned it into a computer monitor (he uses it for a spectrum analyser). The AN5151 takes care of generating the sweep signals from composite sync, and he built his circuit by simply drawing a diagram of the board in the TV and moving the relevant components to a new board. I think I'll do something similar. Hans' site has shown to me that this is not an unrealistic goal. Not trying to be discouraging, whether you successful or not you will certainly learn something. But do be careful. I appreciate both your reply and your concern, but rest assured that I take the voltages seriously and have read up on the matter. I am also not completely unexperienced in electronics, just in this particular field. Bjarni |
#4
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On 2005-09-15, Bjarni Juliusson wrote:
Which is why I decided to go with a resolution close to the original TV resolution, as I mentioned in the original post. If I can get 256 lines at 50Hz, I'll be very happy. So You've figured out how to get that sync rate out of your video card? (if not I have some suggestions) That's half the battle, then all you need to do is combine the sync signals and the video signal at the apropriate voltage levels and feed that to the composite in (or to a rf modulator and to the antenna connection) it may be possible to link directly into the sync circuits of the TV, but doing that could require detailed knowledge of those circuits (like having a service manual....) Bye. Jasen |
#5
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Jasen Betts wrote:
On 2005-09-15, Bjarni Juliusson wrote: Which is why I decided to go with a resolution close to the original TV resolution, as I mentioned in the original post. If I can get 256 lines at 50Hz, I'll be very happy. So You've figured out how to get that sync rate out of your video card? Yes, since I'll be designing the video card. That's half the battle, then all you need to do is combine the sync signals and the video signal at the apropriate voltage levels and feed that to the composite in (or to a rf modulator and to the antenna connection) it may be possible to link directly into the sync circuits of the TV, but doing that could require detailed knowledge of those circuits (like having a service manual....) I think you misunderstood my intentions. I'm not trying to hook my PC up to my TV, I'm trying to build my own CRT control circuits and video circuits. But see the website I linked to. I think I'll do it in a similar way. Thanks for your replies folks. Bjarni |
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