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> If you are stuck with a color TV for your terminal, consider modifying it to accept a signal after the low-pass filter. This is not too hard for someone comfo
by segfaultbuserr 7y ago
> If you are stuck with a color TV for your terminal, consider modifying it to accept a signal after the low-pass filter. This is not too hard for someone comfortable with a soldering iron, someone who isn’t scared of drilling a hole in their TV.
Even better, if you want a color terminal, feed the original RGB signal (or its approximation) directly to your TV, don't use RF modulators or a composite input, so there's minimum degradation of video quality. It should be easy on a relatively modern TV. Follow this flowchart.
1. Is it an European TV with a SCART connector? If yes, it already has RGB input. [0]
2. Does the TV include a YPbPr component input? If yes, read Linear Technology Application Note #57 [1], which shows you a circuit to convert RGB to YPbPr using LT6550 chip (or find a similar commercial converter box).
3. Does the TV have an S-video input? If yes, read Analog AD725 datasheet [2] and use this chip to convert RGB to Chroma-Luma component signal for S-Video (or find a similar commercial converter box).
4. Does the TV have onscreen display (i.e. menus overlaid on top of the image)? If yes, there already exists an RGB signal in the TV for feeding the OSD. You can hack your TV and expose the RGB signal input for your own use [3]. Caution: high voltage, discharge the tube, and never work on it with power on.
5. If everything else fails, don't forget the fact a TV's electron gun is ultimately driven by an RGB signal. You can design a simple driving amplifier to feed the RGB signal directly to the electron guns. Unfortunately, I cannot find a reference design for the moment. But it's doable.
[0] https://en.wikipedia.org/wiki/SCART https://en.wikipedia.org/wiki/SCART
[1] https://www.analog.com/media/en/technical-documentation/application-notes/an57fa.pdf https://www.analog.com/media/en/technical-documentation/appl...
[2] https://www.analog.com/media/en/technical-documentation/data-sheets/AD725.pdf https://www.analog.com/media/en/technical-documentation/data...
[3] https://hackaday.com/2014/09/21/component-video-input-hack-is-a-master-hack-for-crt-televisions/ https://hackaday.com/2014/09/21/component-video-input-hack-i...
- snvzz 7y ago>relatively modern TV Will accept hdmi. The OSSC is an hdmi outputting device that will handle analog input well, as long as it is rgb or ycrcb. Future OSSC Pro will handle composite and s-video as an addon board.
- klodolph 7y agoMy advice was aimed at people living in 1980 who had a spare TV they could use for the computer. I suppose your advice is good for people living in 1990 who don’t have a computer monitor yet.
- DonHopkins 7y agoOnce the Hobart Phase kicks in and has a chance to to work its magic for a few decades, your sagely advice will be relevant once again. https://en.wikipedia.org/wiki/Counter-Clock_World#The_Hobart_Phase https://en.wikipedia.org/wiki/Counter-Clock_World#The_Hobart...
- r00fus 7y agoWow so that episode of Red Dwarf was actually based on this? My respect for PKD rises.
- numpad0 7y agoI just happened to watch a YouTube video on this topic and can’t wish more if I understood it back in 2000s, or even five years ago.
- segfaultbuserr 7y agoWell timed. The appnote [1] I referred to, is a collection video circuits published in January 1994. Linear's effort to republish its old application notes at the beginning of the 21st century is respectable, lots of valuable documentation and tutorials from the 80s are still available in high-quality digital formats.
- Apes 7y agoI get you're excited, but old school CRTs can easily kill a person with the discharge off a capacitor, even when they've been unplugged for a while. It may not be a good idea to casually encourage people to go start hacking on them.
- ryanmercer 7y agoYeah CRT anything is bad news to go tinkering with. High voltage components and the tubes can violently explode if you compromise them, I tossed a monitor into an empty dumpster once and very nearly soiled myself as it happened to fail just right. If you have one open and the CRT tube fails you could very well be picking tiny shards of glass out of your person.
- segfaultbuserr 7y agoNote that suggestion #1, #2 and #3 do not involve modifications of the TV set (and the voltage is a small video signal), so it's risk-free, and should already covered the vast majority of the cases. As for #4, and #5, are more of a possibility and requires knowledge of the internal TV circuitry, those who already have the knowledge to do so, should already be well aware of the dangers involved.