Re: Modeline experiments
 

I have the horizontal scan up i am going to need a position control to work out the amount the correct adjustment to the 5 ohm resistor .
Also will be experimenting with the 2 capacitors on the input and yoke coil
Scans about 10 khz as i will be trying 405 line first when i get the raster correct

Re: Modeline experiments
 

Hi.
Just wondering how many have got this to work successfully.
Recently I've been giving thought to how I want to proceed with the hobby itself and am thinking that if I keep just a couple of sets. The PC based standards conversion is really all I need, I have an ex ITV sound and vision band 3 test modulator that is a superb unit and the vestigial filter too so this would be my source of signal for band 3 and my rod pentode modulator for band 1. The PC is a Dell Optiplex 480 and I wonder if this is suitable with the appropriate graphics card?

Re: Modeline experiments
 

As long as it has a PCI Express slot.

ATI Radeon HD 2400 XT cards are cheap on Ebay, don't forget you need the DMS-59 to VGA Cable.

Re: Modeline experiments
 

Hi Trevor,

I'm using a Dell Optiplex 780 with the HD2400XT sound card.

Peter

Re: Modeline experiments
 

Hello Trevor,

I use a Dell Optiplex 755 with an ATI HD2400XT graphics card.
Only 4 GB memory (Windows 7 32 bit). and a 120 GB SSD.

These days I only use this for 819 lines, but it has been over two and a half years that it was in service. Must see soon if it is still working...

Jac

Re: Modeline experiments
 

I forgot to mention that I had quite a lot of help from Peter Scott in getting everything working properly.

In the end I did not use any additional circuitry to get the synch signals better. Just the simple circuit with resistors and a capacitor which I built into a VGA connector.

Jac

Re: Modeline experiments
 

Hi Peter.
Mine is not a 480 but the same as yours a 780.
Thanks for the info.

Re: Modeline experiments
 

Hi Trevor,

I did try to see what the difference was but failed.

Peter :dunce: ;)

Re: Modeline experiments
 

I use my main computer, an Optiplex 990.

Re: Modeline experiments
 

First up so sorry I have not been active here for a while, been working on the monitor, had a hell of time working out the deflection circuits, I had used them before but was just getting a small raster.

Now on mode line it's really all I need in the lower NBTV range we have other software or low def television, for me on modeline I am now able to experiment above 100 lines.
If we had old 405 line sets here I would use it for this but any thing below 625 I have to convert of make something. I will post up where I am up to today.

Re: Modeline experiments
 

After looking in my shed I found a dual display card! I never knew what it was because that dual VGA cable was missing so didn't know what the plug was! I might have got mode line going early if I knew. Scrapping old PC's in the past I forgot what I had!

Re: Modeline experiments
 

OK on the monitor side I only used the deflection push pull amplifier part of the schematic I posted a while back and knocked together another circuit to drive it. I looked into syncing the ramps today with an LM1881 and this baby has no problem with 405 line rates, so that works. Next I will look into modulation might have a picture to show next time.

Re: Modeline experiments
 

Hi
Great progress indeed.
I've won a graphics card on Ebay for £0.99 and it's been dispatched, so hopefully later in the week I'll get started on this.

Re: Modeline experiments
 

Hi.
I now have the graphics card and it's installed in my Dell Optiplex 780 and certainly operating.
Now to learn what to do next, the PC is dual boot between Windows 10 and Linux Mint 20.3.

How should I proceed now?
I also got a lead with the Graphics card that has two VGA female sockets.

Re: Modeline experiments
 

Can you confirm that the card you have is a ATI RADEON HD 2400XT?
Next step is to download Jeroni Paul's "Winmodelines"
http://www.geocities.ws/podernixie/h...deline-en.html

Then find a spare VGA cable, cut it in the middle, and use one half to make the

"VGA to composite video in black and white" cable
Here:

http://www.geocities.ws/podernixie/htpc/cables-en.html

Re: Modeline experiments
 

Also, the PC needs to see a VGA monitor on each port when booting up.

Whilst a VGA switch-box to switch between one monitor and the modulator is not essential, it does save a lot of messing swapping plugs.

Re: Modeline experiments
 

Many thanks Graham.
I'm sure I've got the correct card I'll need to double check though.
Changing monitor plugs could be an issue so a switch box will be on the shopping list.
I'll work on this over the next few days.
Thanks again.

Re: Modeline experiments
 

Bit more progress on the monitor
I was going for control grid modulation but cathode seems a bit easier on this CRT to modulate only problem it dropped my raster size .
Now after seeing the screen i was wondering what was going on as 625 line mode line was showing all the desktop on my last tv ,but 405 only part of the desktop then i had a look at the settings in the 405 to 625 line and that made sense why i just had to view it ; )
Well that's the reason i used the desk top clock as a television subject .
i have a fair few problems to work out as you see but getting there .

Re: Modeline experiments
 

Here's some video of the results so far 'a work in progress !
https://youtu.be/IkZBFUwLwaw
https://youtu.be/bFdC9xAJ7hk

Re: Modeline experiments
 

Here's some video of the results so far 'a work in progress !
https://youtu.be/IkZBFUwLwaw
https://youtu.be/bFdC9xAJ7hk