Plug for Darius Standards Converter

[peter_scott]

Darius sent me couple of screen shots of his converter.
Given the shape of the mask I assume these are taken
from his Bush TV22.

See http://www.scottpeter.pwp.blueyonder.co.uk/DAR1.jpg
http://www.scottpeter.pwp.blueyonder.co.uk/DAR2.jpg

Peter.

[oldeurope]

tnx Peter
It is the Bush TV22, sorry for the H-lin fault.
I did not find an adjustment for this in the TV22

Darius

[peter_scott]

Hi Darius,

I haven't had my TV22 running for many years but
I think the trimmer capacitor on the component strip
beneath the line output stuff is your horizontal form
adjustment.

In TV32 they moved it onto the rear panel which is
a bit more convenient.

Peter

[oldeurope]

Hi Peter
I'll try it out next time... tnx

Darius

[peter_scott]

Hi Darius,

Sorry, wrong info. It's the trimmer on the scan coils.

Peter.

[oldeurope]

Hi Peter, hi all
I found out new sensational things!
I used Peter's 4046. But only the FF phase detector
(PC2). I did not want to remove my LC-oscillator.
The advantage of this detector is
I can connect the output of the 4040 pin 14 with
pin 14 of the 4046 and I put the H sync to pin 1
of the 93.
So it is possible to reduce the loopfilter cap
from 4,7uF to 10nF !!!
The PLL reacts very fast now.

I standard converted a signal from my satreceiver
and it worked ok. I have ca. 2,3V DC at pin 10 of the
4046 and no ac component.
Then I played a 625 VHS tape.
Now the voltage at pin 10 has an AC component
added caused by the jitter of the tape.
Then I watched the picture in the Bush TV22 and
it was exellent .
The standards converter acts now as a time base
corrector :!!!
Peter's 625 line VHS copy from a copy looks like a DVD
(except the resolution)

Kind regards,

Darius

[oldeurope]

@Jeffrey
isn't it an easy TBC if you take the 625 video out
from pin 3 of the interpolator cxl ?

(I'll try it after my holiday)

Darius

[ppppenguin]

Yes. But only if the oscillator used for output from the CXL is low jitter.

Hi i was directed here by Peter Scott, and as i said to him i am new to this, but Darius' convertor looks great. i would be interested in obtaining the cxl chips, can anyone give me a price? if i can build this my Pye VT17CDL will live again!

many thanks

John Thorn

[oldeurope]

Hi John
tnx for your interest.
New updates are comeing soon for the converter.
The interpolator is much easyer because I generated
a new V-sync. and an advanced clamp for the cxl's
is made.
Of course I can sent you the three cxl's 35Euro
including postage and tech support.

Kind regards

Darius

my email Radio-Darius(at)t-online.de

(at)=@

[oldeurope]

Hi all,
new updates on the website now.
Tried to add a dscription I wrote in WORD but sorry
I am not able to add it here.

Darius

[peter_scott]

Since first building Darius' converter both he and I have
been experimenting with various improvements and simplifications
to the original design.
http://www.scottpeter.pwp.blueyonder.../newscheme.jpg
gives a schematic for a simpler version of the current design.

Darius' converter basically translates three 625 lines into two 405 lines.
One consequence of this is that the position of the discarded line ripples up
through the frame because 625*2/3 has a remainder. An effect of this is that in fine
detail such as small text etc you can see a rippling movement. Darius substantially
reduces this effect by having an interpolator.

The simpler proposal here uses a different approach, namely to stop the
rippling by resetting the line counter at the start of each frame. The downside of
this can be that there is some disturbance of the first few lines at the top of the
picture.

This proposal limits the line sync disturbance by synchronously resetting
the line counter for the duration of one 625 line.

Adding an interpolator improves the presentaion of diagonal picture content
but for those who want a simpler build then this proposal gives good results
and a very stable picture.
http://www.scottpeter.pwp.blueyonder...newschpict.jpg
The schematic is simpler is various ways. Apart from not using a third CXL
for an interpolator the synchronous 74HC163 counter is used for both
the clock division to obtain 2.9MHz and for the 405 line sync.
The two JKs in the vertical sync path simply generate a reset pulse that
is one 625 line in width.
The back to back monostables (bottom right) generate the line pulses
within the frame syncs.

Peter.

[peter_scott]

My photography off the screen isn't very good but
Darius sent me a photo from his TV22 showing
a converted 625>405 test card from the simpler
converter. This was from my converter via a 405 line
VHS tape that I sent to Darius.

http://www.scottpeter.pwp.blueyonder...ewschpict2.jpg

[oldeurope]

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

Good evening,
I made an update for the interpolator in Page 2+5.

The interpolation is made with a 50%/50% average
with the delayed leaved out line and the first
written line and 33% of the delayed first written line
with 77% of the second written line.

It sounds complicated but it isn't. You have only to
put a 470 Ohms resistor between collector of Q26
and the 100uF in Blatt2.

I displaced the interpolator on off switch in Blatt 5.

The interpolation is perfect this way .

Other updates for the PLL and the antialiasing filters
are comeing up as soon as possible.

Kind regards
Darius

[oldeurope]

The antialiasing update is done.
Page 2

Darius

[oldeurope]

http://www.your-normwandler-page.de.vu/
Hi,
I made the PLL Update.
png and tif is not possible, so you have to watch the normwandler website.
(I must leran how to use the new forum.)

Kind regards
Darius

[Paul Stenning]

Hi Darius,

png and tif are now enabled - up to 600 by 600 pixels, and up to 100kB filesize. Let me know if those limits are reasonable (over in the Forum comments section please).