Darius new standard converter for 405 TV

[oldeurope]

Good evening,
to try out many new developments, I build a new analog standard converter.

In the pictures you can see the schematic of the main board,
the mainboard and the converter's inside
and pictures from the DVD players Y- output on my PYE FV1
I got from Mike.

Please tell me what you think about it.

I am happy to discuss and explain the schematic here in the forum.

Kind regards
Darius

http://www.your-normwandler-page.de.vu/

[Nickthedentist]

Good evening Darius.

I'm afraid I have very little knowledge about 405-line TVs.

However, I couldn't look at your posting without congratulating you on the quality and neatness of your construction skills. This has to be the most lovingly built prototype I have ever seen. And your circuit design must be top notch too, judging by the pictures your set is displaying.

[Booby]

The TV picture is quite stunning. Maybe that is an empty cabinet in front of a HDTV set https://www.vintage-radio.net/forum/images/icons/icon10.gif ?

[oldeurope]

Thanks for the congrats.

The camera works like a "pineapple" interpolator, that is why you can
not see the line structure.
I made some pics from the Burosch DVD with PAL and NTSC output
from the DVD- player.
It is nice that you can switch the DVD players output to NTSC.
When I feed the converter with an NTSC input signal it generates
525lines x 2/3 = 350 lines. This means no interlace.
In this picture you can see the line structure.
The pics are made from the screen of the PYE FV1.
I only adjusted the V- hold to lock at the 60Hz.


Kind regards
Darius

[Station X]

Darius.

For the benefit of those of us who are not familiar with analogue scan covertors could you explain in simple terms how it works?

Thanks.

Graham.

[oldeurope]

Hi Graham,
hm it was explaned in the forum but it seems it is erased.
My english is not good and
Jeffrey was so kind and wrote a good text,
maybe he can write it again.

In short words,
every third line (line c in the picture) is leaved out.
If you leave out every third line in a 625 line picture you
get 625 x 2/3 and this is nearly 405 (exact 416 2/3).

Kind regards
Darius

[oldeurope]

Peter Scott made this block diagram for a Harpenden event...

[Paul Stenning]

Originally Posted by Darius

Hi Graham,
hm it was explaned in the forum but it seems it is erased.

A lot of messages have been moved for archiving so are not currently visible, but have not actually been deleted. We'll try to find it and make it visible again.

[ppppenguin]

A lot of messages have been moved for archiving so are not currently visible, but have not actually been deleted. We'll try to find it and make it visible again.

That explains why my message total went down recently!

I rather not have to re-write my explanation of interpolation etc.

[Nickthedentist]

Paul,

It really would be wonderful to have as many of the old postings as possible kept available for us to read, technology and time permitting, of course

So much of the infromation contributed to this forum is unique, and even the tiniest points about the most obscure sets will undoubtedly be useful to someone at some stage. It seems a shame for some of it to disappear.

Reading all the new postings and trying to comit them to memory for future reference is a daunting prospect (for me with my sieve-like mind, anyway).

Keep up the excellent work, and apologies for being OT,

Nick.

[Duke_Nukem]

I've moved the standards convertor threads back for now and added three stars to the front of the title to help find them.

I've only been archiving stuff up to the end of last year thinking they were quiet enough to be moved and edited. Seems I was wrong ?

ppppenguin, rest assured that all posts with useful info in them - which is a lot of them - will be archived in some form.

TTFN,
Jon

[oldeurope]

Good evening,

It seems there are no questions in the schematic.
But I have a few questions to you.

In this converter the sync is eliminated from the video signal
and a new sync is added at the output.

I made me a big head about eleminating the sync from the
video signal and I did it in two steps.

How would you do this job? Are there IC's available which can do this?

Is anyone able to find a datasheet for the delay ccd MSM7403MS?

I tryed the values of the VCR where I found them (8 pin DIL)
and optimized them.

I changed Q29 pos.3b into a MOSFET
and added Q33 pos.6j.

Kind regards
Darius

[oldeurope]

Hi, here is the latest update.

I splitted the DC- restorer and the sync- eleminator.
This means no compromises in searching the right values.

It works perfect now and I am very satisfied with the Mark II converter.

The input signal detector and automatic switching makes the handling
very easy.

Kind regards
Darius

[oldeurope]

Hi,
the pictures show the input signal and the signal at the
emitter of Q8 pos. 6K.
The sync is eleminated and the videotext is suspressed.

Kind regards
Darius

[oldeurope]

Good morning,
the mark II is finished and to make it complete, here are a few updates:

[oldeurope]

... the quick acting V- sync sep developed by PYE inspired me to make
a phase error detector for the delay line clock signal Q27 Q28.Pos.14 C
You can see two screenshots from the oscilloscope. One with phasejump
and the other without the phasejump.

The output of the phase jump det. goes to a monostable pos.16 g.
The monostable generates a "reset (bar)" till there is no phase jump!



In the modulator I used separate filters for sound and vision. So this
modulator don't need a 3,5MHz filter at the vision input.

Kind regards
Darius

[oldeurope]

https://www.vintage-radio.net/forum/showthread.php?t=3723

In the pics you can see the overmodulation detector in the MK II.

Kind regards
Darius

[oldeurope]

http://www.domino405.co.uk/pictures/interpolation.gif

Hi,
reading Jeffrey's article in the latest BVWS Bulletin,
I thaught about the interpolation. Two line or three line interpolation
I don't know exactly how this is defined.

In the link you can see a pic.
Malcolm explains the interpolation of the Domino.

Thinking about my interpolator I now calculated the best values for
the resitors!

(I tryed some values for best results without thinking )

I was sureprised about the result;
The interpolation is perfect now because all 625-lines
are present with the same level in the 405-line picture!

Please look at the schematic for the new values 680 Ohms and 2K Ohms.
I hope the pics explains themself.

Hello Jeffrey, is this a three line interpolation?

Kind regards
Darius

PS: Hi Peter, you must try this!!!

[ppppenguin]

3 line interpolation takes contributions from 3 scan lines to make each output line. It requires 2 cascaded line delays and 3 multipliers.

1 line "interpolation" is merely selecting the nearest line. The result is jagged diagonals.
2 line interpolation is a weighted average of the 2 nearest lines. The result is very good when viewed as a picture but actually reduces vertical definition by more than is necessary.
3, 4 and more line interpolation uses a weighted average of more lines. The weighting function is theoretically a SINC or sin(x)/x curve. In practice this function is too severe and is modified to give the best subjective results. Aurora uses a 3 line interpolator. The BBC digital converter used 4 line interpolation.

BBC trials in the 1970s showed that:
1 line is essential (obviously!)
2 lines give very great improvement
3 lines give useful improvement
4 lines give a marginal improvement
5 or more lines give no useful improvement

[oldeurope]

Hi Jeffrey,
ok but what kind of interpolation do I have here?

I noticed that the digital converters interpolates at the output!?
Mine interpolates at the input.

Maybe you remember my first unswitched interpolator it made a 50%
vertical loss. This means at 600 lines input resolution you get 300
line resolution at 405.
With the new switched interpolator I get 33% vertical loss.
This means I have full vertical resolution at 405.

I made a mistake in my drawing...

Kind regards
Darius