The 3BP1 Anderson monitor

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Re: The 3BP1 Anderson monitor

Postby AncientBrit » Wed Jun 01, 2016 10:25 pm

Well done guys.
A really textbook collaboration.
Pictures look great and as Steve said it's better that the 'scope tube is being used rather than sitting in a drawer somewhere.
I shall be 'lifting' some of the circuits myself.

Congratulations,

Cheers,

Graham
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Re: The 3BP1 Anderson monitor

Postby Steve Anderson » Thu Jun 02, 2016 11:07 am

Thanks Graham. Some 8,000km between us and a time zone difference of 4/5 hours. yet it still got done. But there are a few minor issues that need tidying up.

In time we intend to pull all this together and submit it to Jeremy for possible inclusion in the newsletter so there could well be some small changes in circuits etc. It may be so that not only the 3BP1 CRT is covered but the last remaining easy-to-get 3" CRT in Europe is also included, the DG7-32. It has the advantage of not requiring quite so high voltages.

In general the whole thing could be applied to any electrostatic deflection CRT, it's just the tube requirements need to be met.

Steve A.
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Re: The 3BP1 Anderson monitor

Postby Harry Dalek » Thu Jun 02, 2016 2:54 pm

Thanks also Graham for the interest never know who's viewing but knew you were :wink:
This video was the first i wanted to display but it went missing till i tracked it down so its ended up being the finale...
As Steve mentioned The Anderson Monitor will i hope end up in the news letter which would be nice and a good one as any one can come back here and review the build so don't make my mistakes and earth the thing !
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Re: The 3BP1 Anderson monitor

Postby Panrock » Fri Jun 03, 2016 9:46 pm

And a "well done both" from me too.

This sort of cross-border teamwork would have been impossible (or at least very difficult and slow) without the internet. New technology in the service of the old! (Well maybe not quite so 'old' bearing in mind Steve A's advanced techniques).

You have built a really useful bit of kit there Harry. My 'Argus' is about 20 times as heavy and unwieldy and in any case doesn't go down to NBTV standards.

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Re: The 3BP1 Anderson monitor

Postby Harry Dalek » Sat Jun 04, 2016 12:27 am

Panrock wrote:And a "well done both" from me too.

This sort of cross-border teamwork would have been impossible (or at least very difficult and slow) without the internet. New technology in the service of the old! (Well maybe not quite so 'old' bearing in mind Steve A's advanced techniques).

You have built a really useful bit of kit there Harry. My 'Argus' is about 20 times as heavy and unwieldy and in any case doesn't go down to NBTV standards.

Steve O


Thanks Steve yes correspondence construction ! :wink:

Wish the case was a bit neater but i am not good at cases ,i wanted it the size of my little Trio scope which it ended up being a touch smaller .

OH the Argus is a thing of beauty working on another lost standard so nice to have and size wise your sort of stuck with the size of the tube but i know what you mean ....these days i think more how small can i make it if possible ...
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Re: The 3BP1 Anderson monitor

Postby Steve Anderson » Sat Jun 04, 2016 11:31 am

Thanks too Steve.

For some reason a day or two ago I read through the entire thread from Harry's first posting. The collaboration, well, it just 'happened'. We didn't set out with that intention, yet somehow it came about.

Late last year I had plenty of time on my hands so it was something in addition to the things I was doing here to keep me off the streets. Towards the end it was a bit stop-start-ish as things got busy this end. But it did eventually get done after some six months.

An advantage of posting the progress here, or lack of it, is at acts as a diary, a journal. It reminds one of the pitfalls we fell into, the 'one step forward, two steps back' scenarios. When you're building something solo often the road to success goes unrecorded, just the final successful outcome is published or posted.

I have tried to record my own solo efforts with the SSTV-625 Up Converter, within which you'll notice that Klaas had a significant amount of input. I really, really must get on with the NBTV-625 version of it!

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Re: The 3BP1 Anderson monitor

Postby Harry Dalek » Sat Jun 04, 2016 10:28 pm

Yes just sort of happened i am pleased it did as my results if any would i am sure been ruff...the correct power supply and modulation circuits sure helped !
Working on some pictures some work out others not camera shots are hard.
Yes Steve working on the NBTV side of your video converter will be great to see !
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Re: The 3BP1 Anderson monitor

Postby Klaas Robers » Sun Jun 05, 2016 7:38 am

Harry, I have the feeling that your pictures are too high or too narrow. You will be able to adjust somewhere the picture heigth and the picture width. NBTV pictures should have an aspect ratio of 2 : 3, or 1 to 1½. That is INCLUDING the sync pulse, so in practice it will be closer to 3 : 4. If you have the Grant Dixon test picture, the circle should be a true circle. However there are more frames with a circle.

On the page http://www.nbtv.org/sound.htm you will find almost at the bottom a button to download the file http://www.nbtv.org/nbtvideo.zip. Unzipped this will give you a wav file which includes the Grant Dixon picture.

The frame sync is also a problem. Because of the missing sync pulse, the sync separator gives the pulse half way line one, the line of which there is no preceding line pulse. In most cases this causes that you will not see line 1. For a mechanical Nipkow disc this is not a problem, as line 1 always follows automatically line 32. This is much more difficult for an electronic monitor.
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Re: The 3BP1 Anderson monitor

Postby Steve Anderson » Sun Jun 05, 2016 1:00 pm

Agreed Klaas, fine adjustments Harry hasn't got around to yet. The aspect ratio needs slightly more horizontal drive, indeed so too could the vertical to use as much of the screen as possible, then re-centre.

The arrangement of the frame sync is that with a simple manual adjustment of one of the monos line one can be fully visible. A trace of the result is below. The yellow trace is the source video showing the missing frame sync, the magenta one is the 'missed the bus' mono which triggers another pair of monos to generate a frame sync (cyan trace). This can be adjusted +/- about a line to place the retrace correctly.

Steve A.
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Re: The 3BP1 Anderson monitor

Postby Steve Anderson » Sun Jun 05, 2016 1:37 pm

Harry Dalek wrote:...the NBTV side of your video converter will be great to see !

There are a few non-NBTV things I need to do first but I hope to make a re-start on the NBTV-625 converter before the end of the month. The hardware is all done as part of the SSTV-625 converter the only change is the software in one of the micros...but it is a significant change. Rather than attempt to re-work the SSTV software to fit I'll start from scratch - probably a better way of preserving what sanity I have left!

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Re: The 3BP1 Anderson monitor

Postby Harry Dalek » Sun Jun 05, 2016 4:26 pm

Klaas Robers wrote:Harry, I have the feeling that your pictures are too high or too narrow. You will be able to adjust somewhere the picture heigth and the picture width. NBTV pictures should have an aspect ratio of 2 : 3, or 1 to 1½. That is INCLUDING the sync pulse, so in practice it will be closer to 3 : 4. If you have the Grant Dixon test picture, the circle should be a true circle. However there are more frames with a circle.

On the page http://www.nbtv.org/sound.htm you will find almost at the bottom a button to download the file http://www.nbtv.org/nbtvideo.zip. Unzipped this will give you a wav file which includes the Grant Dixon picture.

The frame sync is also a problem. Because of the missing sync pulse, the sync separator gives the pulse half way line one, the line of which there is no preceding line pulse. In most cases this causes that you will not see line 1. For a mechanical Nipkow disc this is not a problem, as line 1 always follows automatically line 32. This is much more difficult for an electronic monitor.


Hi Klass
As with Steve theres a bit of your mind in this monitor as well with the sync circuit so thank you for that ! Yes i didn't really think of the correct aspect ratio not really much of a problem with the size controls but how close i am here is to my eye which isn't the best of tools these days .
I Gave Mr Dixons test cards a go adjusting the size controls so might be looking closer to club standard.
Seemed to play ok as it Should with Steve and your circuits . :wink:
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Re: The 3BP1 Anderson monitor

Postby Harry Dalek » Sun Jun 05, 2016 5:23 pm

OK Steve i will try and increase the size for maximum display ,don't know why i have not tried it think i was just happy with my lot as it was set at .i will try.
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Re: The 3BP1 Anderson monitor

Postby Klaas Robers » Sun Jun 05, 2016 11:12 pm

Harry, Looks better. May be that the largest possible size is not the best setting. At a certain moment you are going to see the lines separating. Then you are too far. As well, when you are scanning too close to the edges of the tubes screen, the scanning becomes non linear. the rectangle of the picture then gets the shape of a pillow or a barrel. This is also called "pillow distortion" and "barrel distortion".
So it is not unwise that the corners of the picture are free of the edges of the picture tube.

On the Grant Dixon test picture you might use a ruler to make the circle a true circle..... Grant calculated it to be a circle.

You will see that this picture has a vertical grey scale at the left and at the right. This grey scale is two lines at both sides. If your frame sync is delayed you will see a wider grey scale at the left side (two lines) and a narrower (one line) at the right side.

Good luck..... It is amazing
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Re: The 3BP1 Anderson monitor

Postby Steve Anderson » Mon Jun 06, 2016 1:12 pm

All correct, in the screen-shot below you can see barrel distortion setting in on the top few lines and the line-spacing becomes greater as the vertical deflection angle becomes larger. It's not so visible at the bottom as it's not quite as close to the screen edge. So as ever, it's a compromise.

You can apply correction waveforms to the deflection signals to correct for this, but it does become quite complex and in my opinion not worth it here.

In this shot the CRT wasn't quite focused correctly, it was a trial shot as I set things up. The CRT was a 3" (7cm) DG7-32 used here in a 48-line 4:3 format. The photo was changed to greyscale to get rid of the green colour and cropped to size.

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Re: The 3BP1 Anderson monitor

Postby Steve Anderson » Mon Jun 06, 2016 6:30 pm

Rather than make a start on the NBTV-625 Up-Convertor software, I've decided to finish off the opposite direction device, 625-32. I've started a new thread called "The 'Hellcat MK I' 625-32 Converter." as I wasn't able to locate the old one!

I will get on with the 32-625 converter in due course.

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