If you really, really, must do this: https://www.ebay.com/itm/314347957394

keenmaster486 wrote on 2023-05-11, 03:25:

If you really, really, must do this: https://www.ebay.com/itm/314347957394

Thanks for the help. The monitor specs says it is 15.75khz via composite. Since vga-to-composite is NTSC TV signal, will it damage the monitor?

That is NTSC.

thanks for the help. I've ordered that device

I think the same.

The converter even has an NTSC/PAL switch on the side.

Some background information..
Both NTSC and PAL (+SECAM) are color standards.
They're based on their older monochrome brothers, RS-170 (equals monochrome NTSC) and CCIR (equals monochrome PAL).

More information: https://www.epanorama.net/documents/video/rs170.html

While they differe a bit in detail, they're mostly compatible.
You can feed an NTSC or PAL signal into a monochrome video monitor, it won't hurt.
The only major difference is the 50Hz/60Hz difference.
If incorrectly set, the picture scrolls up/down. It can be adjusted by a potentiometer on the back (v.hold).

thanks man. learning something new everyday

Jo22 wrote on 2023-05-11, 06:36:

I think the same. […]
Show full quote

I think the same.

The converter even has an NTSC/PAL switch on the side.

Some background information..
Both NTSC and PAL (+SECAM) are color standards.
They're based on their older monochrome brothers, RS-170 (equals monochrome NTSC) and CCIR (equals monochrome PAL).

More information: https://www.epanorama.net/documents/video/rs170.html

While they differe a bit in detail, they're mostly compatible.
You can feed an NTSC or PAL signal into a monochrome video monitor, it won't hurt.
The only major difference is the 50Hz/60Hz difference.
If incorrectly set, the picture scrolls up/down. It can be adjusted by a potentiometer on the back (v.hold).

Old 386 PC with CRT Tv

"composite monochrome monitor" looks weird...

composite = luminance + chrominance

A monochrome monitor has no use for chrominance, so the preferred input is pure luminance.

Yes, you can feed a monochrome monitor with luminance+chrominance, but it may degrade picture quality.
And the picture quality resulting from downsampling VGA signal to 15 kHz is not going to be great anyway.

Grzyb wrote on 2023-05-11, 08:14:

And the picture quality resulting from downsampling VGA signal to 15 kHz is not going to be great anyway.

This. Don't expect any miracles; it might be usable at 320x200 if you aren't picky.

Grzyb wrote on 2023-05-11, 08:14:

"composite monochrome monitor" looks weird...

composite = luminance + chrominance

I thought the "composite" descriptor referred to VBS (video, blanking, and sync on one connector). Video was originally luminance only, then we started seeing "CVBS" ("C" for "color").

VileR wrote on 2023-05-11, 19:03:

Grzyb wrote on 2023-05-11, 08:14:

"composite monochrome monitor" looks weird...

composite = luminance + chrominance

I thought the "composite" descriptor referred to VBS (video, blanking, and sync on one connector). Video was originally luminance only, then we started seeing "CVBS" ("C" for "color").

That's also a valid interpretation, I think.

But in practice, I tend to not call VBS "Composite".

Composite has a bad stigma and most people think of it as the video cable with the yellow RCA plug..
Which doesn't do justice to the underlying high-quality monochrome video.

It would also confuse people when they use S-Video.
The Luma pin carries the monochrome video signal with sync/blank, the differencial colour signal is on a separate.
If someone calls this Luma signal a "Composite" signal, some people would wonder why there is dirty Composite video inside the S-Video plug,
because they were told that S-Video was using separate video information.

To me, Composite equals CVBS, as Grzyb described it.
But again, your interpretation isn't wrong.
Maybe that was the original meaning all together. 🤷‍♂️

On the other hand, I never heard about a classic broadcast video signal that doesn't use a combined Luma/Sync/Blank signal.
So I wonder which practical purpose the Composite term would have had, if it existed in the monochrome era already.

Hm. Another possible description for VBS/CVBs might be "baseband video signal".
Which it is before it gets modulated on an RF carrier eventually (in the past, I mean, when analogue terrestrial TV was still common).

PS: In the past, when I was very young, I didn't know the term "Composite", even.
I only knew about 'video signal" and "AV" signals (analogue audio/video). And Luna/Chroma or "80 character video", a reference to the higher end inputs of the classic Commodore 1702 monitor.
To me, the "Composite" term, pretty much like the "RCA" connector name,
is an American or international thing which I began
to hear quite often after the www became popular in daily life.

Grzyb wrote on 2023-05-11, 08:14:

A monochrome monitor has no use for chrominance, so the preferred input is pure luminance.

In theory, yes. But higher end monitors shouldn't let the colour carrier reach the monochrome monitor's video stage.
There should be low-pass filters who cut off the video information.
In practice, however, the colour signals cause dot patterns on a monochrome screen.

Grzyb wrote on 2023-05-11, 08:14:

Yes, you can feed a monochrome monitor with luminance+chrominance, but it may degrade picture quality.

Yes, a bit, yes. It's bearable, though. Depending on the monitor/input signal, it doesn't stand out much.

Grzyb wrote on 2023-05-11, 08:14:

And the picture quality resulting from downsampling VGA signal to 15 kHz is not going to be great anyway.

Well, yes and no. I'm using a Surfstation JNT set-top box with a Cyrix Media GX.
The motherboard contains an VGA to Composite converter and the output is nice on a monochrome green monitor.
Windows 3.1x with 640x480 256c driver looks nice and detailed, despite the colour information.
I'm still working on a mod to get pure Luma out of it, though. So your points aren't wrong, either.

Here are some videos for comparison (Surfstation JNT via CVBS on green monitor) :

https://m.youtube.com/watch?v=A0_Ziif3DEQ

https://m.youtube.com/watch?v=11A9YZyuguA

https://m.youtube.com/watch?v=sHp1rJPXfLQ

https://m.youtube.com/watch?v=3T1BB7jABqc

https://m.youtube.com/watch?v=wSM-uUkklHM

https://m.youtube.com/watch?v=9MssZ61Ux48

https://m.youtube.com/watch?v=eCfG5hTRc5U

https://m.youtube.com/watch?v=7BLD1qIZQos

Edit: The flicker is a technical issue. The monitor runs at 60Hz, because of NTSC supporting VGA's 640x480 resolution natively.
The camera, however, was using 50Hz for recording..

Edit: The Surfstation has a PAL 50Hz / NTSC 60 Hz jumper on motherboard..
It can output in/scale to 640x480 or 720x567, as far as I know.
Unfortunately, there's no custom 720x567 VGA driver for Windows 3.x..