Using a monitor as a TV

[SteveC]

Hi all,

I've seen in the past, but I can't find now, schematics on how to build a circuit which will take an RGB scart and convert it to a VGA signal. Any ideas where I might find this?

[villerk]

Does it work other way round? Then I'll finally be able to use that TV under Linux!!

Have you tried EPanorama?

[Belwarrior]

can anyone post a link here, as i would like to try doing the circuit myself (once i find my soldering iron and the stuff)

[Michel Carleer]

I think you will have quite a hard time inputting a TV signal into a PC monitor, unless it is a very old one. The reason is that today's monitors cannot sync anymore to the TV vertical and horizontal scan frequencies (25/30 Hz and ~15 kHz respectively, compare to the specs in your monitor manual).
However, several LCD monitors have S-Video and/or Composite inputs, together with appropriate scan multiplying electronics inside. Don't know if equivalent CRT's can be found.
Michka

[SteveC]

Originally posted by Michel Carleer
I think you will have quite a hard time inputting a TV signal into a PC monitor, unless it is a very old one. The reason is that today's monitors cannot sync anymore to the TV vertical and horizontal scan frequencies (25/30 Hz and ~15 kHz respectively, compare to the specs in your monitor manual).
However, several LCD monitors have S-Video and/or Composite inputs, together with appropriate scan multiplying electronics inside. Don't know if equivalent CRT's can be found.
Michka

Yeah I know, but I once saw a schematic which included some components which converted the 15kHz horizontal scan to the required 31kHz. I don't wanna do it if it's going to cost a bomb though

[Michel Carleer]

I agree, the scan doubling components may well be reasonably inexpensive, as they are used in the so called 100 Hz TV sets (at least that's the name here in PAL/SECAM Europe). Which means mass production resulting in low cost.
Michka

[dave m]

Steve, this is a bit outside my field, but is this the sort of thing Amiga owners built to display on PC monitors? If so this may be the sort of thing you're after, if not a hunt around Amiga forums may help. I've pasted some text in, if you stick it into notepad it might make more sense.

HTH

Dave



Hi all,

Here is an adapter I've been working on to get vga output without a
Second Sight card. Any techies out there want to look this over and see
if it works for you. Build and use it at your own risk as I haven't
tested it yet.

---------------------------------------------------------------------------=
-

GS RGB to VGA Video Adapter

Here is a GS RGB to VGA converter adapter based on the VGA Hack for
the Amiga which also uses analog RGB and works great. It will allow
the use of a vga monitor on a GS. The original VGA Hack diagram can be
found on Aminet (the big Amiga FTP site) under hardware hacks.

The Amiga uses separate horizontal and vertical sync so I used 330 ohm=
=20
resistors (as suggested by someone in the Atari ST newsgroup) and tied
them together to split the composite sync. This allowed me to get a
separate H and V sync to send to the various pins on the 74LS08N chip.

GS Male to VGA Female converter 74LS08N chip
-------
GS Male # 2 Red -----------> VGA Female # 1 |-->--->H Sync > |1 14|
GS Male # 5 Green ---------> VGA Female # 2 |-->--->H Sync > |2 |
GS Male # 9 Blue ----------> VGA Female # 3 | V Sync < |3 |
| |--->V Sync > |4 |
GS Male # 3 Comp. Sync ----> 330 ohm res -> H->| |--->V Sync > |5 |
" " " " " " ----> 330 ohm res -> V---->| H Sync < |6 |
-------

GS Male # 1+6+13+Shell GND ----------> VGA Female # 4+5+7+8+9+11
_|_
100
=E6F
---
|
+5v from MB -------------------------> 74LS08N pin # 14

Horizontal and vertical sync outputs from chip go to the following:

H Sync > VGA Female # 13
V Sync > VGA Female # 14

You will need to build this on a small PCB (printed circuit board) which
is obtainable, as well as the 74LS08N chip, from Radio Shack.

Note the directional arrows on the diagram above as pertaining to the
74LS08N chip. Horizontal sync goes IN via pin #1 and 2 and are joined
together on the PCB and then exits to Vertical sync via pin #3. Vertical
sync goes IN via pin #4 and 5 and joined together on the PCB and exits to
Horizontal sync via pin #6.

+5 volt goes from GS motherboard to pin #14 on 74LS08N chip.

--------------------------------------------------------------------------

Disclaimer:

Be warned that using this adapter is 'AT YOUR OWN RISK' as is any
after-market hack. No guarantees or warranties implied or given with this
diagram and instructions. Hopefully it won't blow up your GS. The final
result will require plugging into a vga (male) cable. The converter will
plug right into the GS. Let us know your results.

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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D





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In article <Pine.GSO.3.95.iB1.0.1010516001450.29809B-100000@halifax.chebucto.ns.ca>,
Tony Cianfaglione <ab616@chebucto.ns.ca> wrote:
> Here is an adapter I've been working on to get vga output without a
>Second Sight card. Any techies out there want to look this over and see
>if it works for you. Build and use it at your own risk as I haven't
>tested it yet.

This circuit does nothing for the refresh rate, which is outside the range
of most modern VGA monitors (some older models, like the NEC MultiSync 3D I
use, can handle the GS's 15.75 kHz horizontal sync rate.) What could be
more useful would be this sync doubler:

http://www.aminet.net/~aminet/dirs/aminet/hard/hack/Syncdoubler.lha

A conversion of this archive to something readable by a wider variety of
computers is on my website:

http://salfter.dyndns.org/files/Syncdoubler.zip

I haven't tried building this gadget yet, but it looks like it would double
the horizontal scan rate. It also looks at first glance, though, like it
would only display half of each scan line...unless I'm reading something
incorrectly. It uses a 74LS123, three 2N2222s, and a few passive components
and could be lashed together quickly enough to see if it'll get the job
done.