NTSC RGB -> VGA

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If I use an LM1881 IC to strip the H and V sync off of an EIA RS170 sync
on green video signal (NTSC?), could I then apply the RGB video lines
and sync signals to a standard LCD or VGA computer monitor?

The RGB video signals are 0.7V analogue, 16kHz Horiz, 720 x 540
dots/lines resolution.

The other problem is finding a source of 12 to 13" Monitors, Google has
turned up a few overseas but none in Aus.

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Also looking at 15" and 17" monitor specs I notice they have a minimum
30kHz horizontal scan, where as my signal is 15kHz. Any ideas?

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I don't think you'll find any multisync monitors made in the last ten years
that go down to 15kHz, except those already designed for TV use.

MrT.



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Is used gear ok? how about an 80's analog computer monitor (eg
commodore 1084). Shouldn't be hard to find one on ebay.

If you don't mind a not-so-perfect image you could simply use a TV as
a monitor, just find one with a SCART socket. The only problem I can
see here is that TVs with SCART don't usualy come any smaller than
19". Though I've noticed that some small TVs (esp from sharp, samsung
and lg) use a signal processing IC designed to accommodate a SCART
connector, so modifying the TV for an RGB input is trivial (3
terminating resistors and 3 coupling caps).

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Thanks for the replies, I did a bit of Googling and the info on trying
to get old video arcade games to connect to TVs and monitors is pretty
much what you have covered.

It's a replacement for a few very old process control monitors on a
ship. The sensors and processing are ok but the monitors are
unserviceable. Apparently replacements were not available.

But I have found a company in the UK that make exactly what I'm after (
http://www.kme.co.uk/ ) - it just comes down to the price now

If they are too expensive I'll try RGB -> composite conversion using
something like the Motorola MC1377 and send it to an LCD or CRT TV
monitor and see what the quality is like.

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yeah, well for a small computer accurate display you can always try
australian electronics catalogues like "farnell" for "price".

they'll have small CRT's of some sort.

TV's look a bit unprofesional, with their tuning buttons and speakers..




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buy a modern TV, with no buttons other than on/off. Just dont lose the
remote control :)

Cheers
Terry

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the mc1377s are pretty crappy...there was one of them in my old amiga
modulator - 80 col text was unreadable

maybe the newer encoder chips are better...
if you could live without colour you could just sum the red, green,
blue and sync with a fast op-amp to make monochrome composite

Give the TV/SCART modification a try - it's a bit easier that building
a CVBS encoder circuit. All the LG tvs have a spot for a SCART socket
(I just had a look through my archive of LG circuits and they all have
this) on the PCB (under the AV sockets). It's simply a matter of
removing the AV socket block, putting in a scart socket, installing
the missing termination resistors and a few wire links.

I'm pretty sure the samsung ones are like this too but i've got no
circuits for 14" samsung tvs so I can't be certain.

pulling pin 8 of the scart to 12v and pin 16 to 2v will force the TV
into RGB mode and act as a monitor. The Sync goes into the video input
- 0.3vp-p/75R.

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TOO SLOW for a standard VGA CRT !
The CRT's expect at least 50Hz vertical and 30kHz horizontal.

So you are hitting it with 16kHz and 30Hz..



Perhaps an LCD can do it - they often have tuner attachements optional.



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yeah its hard to find a small CRT.

easy to find small TV's, what are you doing ?? why not convert  current
signal to  Composite  ??




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Yeah it looks like that's what I'll have to do.
See my post above.

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What about getting a US NTSC lcd display ?
Lots of industrial types.

Earthlcd.com carries lot but will rip you big time on shipping
(plus java based website)
They have 11.3 and 12.1 inch lcds
http://store.earthlcd.com/s.nl/c.318770/sc.7/category.16/.f

Will need to get power supplies as well
May need to get a mositure proof casing

Going to be pricey unless you can buy second hand.

Alex



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