The 405 line monitor MK2

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The 405 line monitor MK2

Postby Harry Dalek » Sun Jul 31, 2022 9:00 pm

Mk2 405 line construction is already on the way and have already got the Horizontal ramp generator syncing .
Mk1 was ok :roll: got a picture up in 405 but i think i can do better .
The deflection amp transistors are mounted hooked up this was another part of the last circuit i was happy with .
The deflection yoke Resistors i have left those again mounted on the heat sink for now and easy to change when i tweak the H and V line width .
The board is a lot smaller than the last one as i found it was to big first time around than what was needed .
I have changed the ramp generator and should have better position and size control of the raster .
And as for the CRT this is still up in the air if i go with the same one or not i do have others .
Power supply will be reused from MK1 should go a bit quicker this time around .
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DSCN8643.JPG
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Re: The 405 line monitor MK2

Postby Harry Dalek » Sat Aug 06, 2022 5:27 pm

So far finished the sync lM1881 sync separator
R (1).jpg
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The H and V outputs are fed to the Ramp generator via a capacitor to pin 5 of the 555 for syncing
Screen 00007.bmp
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Flexible_ramp_generator_555 (1).pdf
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I used this Ramp circuit on the passive modulation NBTV scope circuit a few years back here i have adjusted increased 470ohm resistor on the Vertical and capacitors on both to run around 10khz and 50 hz
Original circuit video below ,looked very useful to my needs
https://www.youtube.com/watch?v=bVahBmsvirE&t=620s
My circuit at the moment syncing to 405 line
Finding the video bar is not working to share video but i will put it up in can it can be fixed
DSCN8649.mp4
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405 line to the Lm1881 below
DSCN8656.JPG

My board below running circuit on dual 12v supply
DSCN8648.JPG
Attachments
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Re: The 405 line monitor MK2

Postby Harry Dalek » Fri Aug 12, 2022 10:03 pm

At the Raster stage and seeing how well its doing compared to Mk1 i can see the linearity is not as good as Mk1 both didn't have feed back but this one is for sure more off.
The sine wave fly back looking line is there again.
Positioning size control is much better on this one i might have to have another look the deflection side so i have some feed back happening .
As you see a little messy testing and adjusting the deflection amplifier transistors.
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DSCN8664.JPG
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The 405 line monitor MK2

Postby Harry Dalek » Sat Aug 13, 2022 4:07 pm

Well the linearity was an easy fix just increasing the capacitance feeding the ramp to the vertical deflection amplifier.

DSCN8671.JPG



I also found on The horizontal a push pull amplifier was not necessary at all cut down the warming of the Transistors as well so just have a power PNP doing the job on 10 volts .

DSCN8676.JPG


The fly back line looks more like flyback than a sine wave as the last monitor go .
Well that's where i am up to at the moment unfortunately i did in my Lm1881 in and have to wait for the spare to turn up i forgot i had it on the variable supply and went over its operating voltage adjusting the deflection amplifier :roll: get back to it when i have a new one .
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Re: The 405 line monitor MK2

Postby Steve Anderson » Sat Aug 13, 2022 5:41 pm

Well, Harry, as usual, you've managed something I wouldn't even attempt! How in the heck you get these things going is beyond me.

Right, the next thing is 1) getting it locked to a source of 405...do you have a source? 405 as far as I'm aware was not used in Australia.

Second 2) will be retrace blanking, i.e. cutting off the beam during retrace. Then, combined with the previous, adding the video modulation. I'm also in a non-405 country, where I might get some source material is a good question....

Pondering upon it a 'simple' 625 to 405 converter shouldn't be that difficult. OK, it'll never meet the standards required by the BBC (God bless 'em) But to get something on a screen it's not an impossible task....I've got a feeling I may have started something along these lines years ago...

I also recall the UK IBA published a 'guide' to standards conversion, sometime in the early 80s? Maybe before...time for a deep dig...not only 625 to 405, but 525-625 in both directions. All monochrome though. Adding colour though a nuisance isn't too onerous, just a hassle.

Of course, something like the WC-01 is a benchmark for classic standards conversion. Its flexibility is unquestioned, however how often do you need all those various modes? Not that often probably. If I were looking for a standards converter where would I place my money? For the moment let's forget colour.

1) 525-625 (A luxury)
2) 625-525 (Ditto)
3) 405-625
4) Maybe 625-405, a real 'maybe'.
5) 625-'Standard' to NBTV (32/12.5)
6) NBTV (32/12.5) to 625

Whilst about it throw in a few SSTV modes as well...maybe...but that's just me, not a major application.

Then add in to the mix some VGA output modes too...Oh heck! See what I mean? How the WC-01 came to fruition is amazing, considering the complexity of its remit.

Steve A.
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Re: The 405 line monitor MK2

Postby Harry Dalek » Sat Aug 13, 2022 9:41 pm

Steve Anderson wrote:Well, Harry, as usual, you've managed something I wouldn't even attempt! How in the heck you get these things going is beyond me.


Hi Steve
Well i wish i had your Brains but i have to make due with bits of information i recall and trial and error when i am a bit lost .
The Magnetic deflection amplifier or the Yoke really is a dreadful fussy beast but i took on the rubbish in rubbish out advice and make sure what's going into it is correct ,then its just a matter of getting the amplifier to its job .

Right, the next thing is 1) getting it locked to a source of 405...do you have a source? 405 as far as I'm aware was not used in Australia.


1948
FIRST ALL-ELECTRONIC TELEVISION CHAIN TO REACH AUSTRALIA was this British Pye 405-line closed circuit outfit at the end of 1948. Astor Radio (Radio Corp of Australia) and Pye toured with public demonstrations of this outfit around agricultural shows in various parts of Australia. It was a blatant attempt to pressure the Australian government into the usage of the British 405-line system.
I am very surprised how pro British Australia was back then we didn't just go 405 line because of that ! There was also around the time 625 line tests in Sydney so Sydney wanted 625 line and Melbourne 405 line and Sydney Tests must of went better .
Reason i want 405 line is we have no old Televisions to collect or try in Australia and this idea to use the PC as a systems converter came up a great excuse for another monitor try since now there's video signal to use in the first place not only that with a PC you have either live or recorded what ever a normal systems converter can out do a PC as far as what to display ?

57311693_10214261641034728_8253849247854624768_n.jpg

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So it was used in an experimental use but i will just use my PC Again as in used for MK1 circuit go

Second 2) will be retrace blanking, i.e. cutting off the beam during retrace. Then, combined with the previous, adding the video modulation. I'm also in a non-405 country, where I might get some source material is a good question....


As below Trevor i and a fair few others are using our desktop PC via ATI Radeon 2400 XT old gaming video card which can be programed to output just about any thing from around 100 to over 800 line .
Just have to either use a mode line already made up and copy paste it in or you can program menu ,can do your own in the settings if you wish ,i have not tried to adjust any thing out of standard 240 line 405 line 441 line so on yet .
I want blanking i don't want to see those retrace lines so i will more than likely again experiment on modulation first before then work on Blanking


youtu.be/IrTNk3yB3iU


Pondering upon it a 'simple' 625 to 405 converter shouldn't be that difficult. OK, it'll never meet the standards required by the BBC (God bless 'em) But to get something on a screen it's not an impossible task....I've got a feeling I may have started something along these lines years ago...


You have to think the Pc's VGA card all out do our old analog standards only problem most nearly all are stuck in its own build in standards which don't match our old tv standards my video card can be adjusted line and frame rates to a much greater range by using the modeline program ,its a dual display so one display is vga standard the other when used with mode line switches to this case 405 line 10.1khz 50hz off the top of my head .

I also recall the UK IBA published a 'guide' to standards conversion, sometime in the early 80s? Maybe before...time for a deep dig...not only 625 to 405, but 525-625 in both directions. All monochrome though. Adding colour though a nuisance isn't too onerous, just a hassle.


It does and can output 525 625 line also easy

Of course, something like the WC-01 is a benchmark for classic standards conversion. Its flexibility is unquestioned, however how often do you need all those various modes? Not that often probably. If I were looking for a standards converter where would I place my money? For the moment let's forget colour.

1) 525-625 (A luxury)
2) 625-525 (Ditto)
3) 405-625
4) Maybe 625-405, a real 'maybe'.
5) 625-'Standard' to NBTV (32/12.5)
6) NBTV (32/12.5) to 625


Well i should of said this is all B/w but only reason the 3 colours are tied together via resistors for B/w you could add circuits for either FSC or pal Secam NTSC if it really was wanted ,i am happy with b/w at the moment FSC for say 405 would be fun perhaps one day .

Whilst about it throw in a few SSTV modes as well...maybe...but that's just me, not a major application.

Then add in to the mix some VGA output modes too...Oh heck! See what I mean? How the WC-01 came to fruition is amazing, considering the complexity of its remit.

Steve A.


The WC-01 video converters Aurora great thing indeed for a every thing ,but the ATI Radeon 2400 XT video card B/w can sort match it over 100 line b/w as i said colour you would have to add circuits still 30 dollars hate to think what the Aurora costs ...making something along those lines cheaper would be good too i had a need here so my cheapy version is pretty good results and cost wise.
https://www.tech-retro.com/aurora-design/wc.html It would be a wonderful thing to own if you have a need being me i could get a fair few projects out of it making monitors for fun and those using it for vintage tvs be perhaps wasted only using 2 or 3 systems it could do .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The 405 line monitor MK2

Postby Steve Anderson » Sun Aug 14, 2022 3:22 pm

I haven't looked into this in detail, but a 405-to-625 convertor wouldn't be that difficult if you're OK with the 405 source only taking up around 65% of the 625 frame (both horizontally and vertically). So it would be viewable, just somewhat smaller...bearing in mind TVs of the 405 era had smaller screens than what we are used to these days.

Then there is the small problem of source material, after a while a test-card becomes a tad boring. There is a case for a 625-405 version.

A revision of the SSTV-625 convertor I made a few years ago may be in order....the output side (625 read mode) is already done and shouldn't require any modification (I think). The input side (now 405 write) would require significant work, both in hardware and software. A small plus-point is there's no requirement for a demodulator, simply baseband 405 in.

Steve A.

Maybe just a 625-405 down-convertor is actually all that's needed? Do we need to convert 405 to 625? In other words, for those that own a WC-01 what is its primary use? For those that would like to own one, what major use would you use it for?

As ever, specifying a suitable video A-D is a hurdle....but as mentioned elsewhere/previously, the TLC5540 appears suitable....though not available in a DIL package, only SO (useable...just) or TSSOP (unusable).
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Re: The 405 line monitor MK2

Postby Harry Dalek » Sun Aug 14, 2022 7:27 pm

Steve Anderson wrote:I haven't looked into this in detail, but a 405-to-625 convertor wouldn't be that difficult if you're OK with the 405 source only taking up around 65% of the 625 frame (both horizontally and vertically). So it would be viewable, just somewhat smaller...bearing in mind TVs of the 405 era had smaller screens than what we are used to these days.


I think there are still a lot of 405 line collectors out there but i think if you have this hobby you might already have a systems converter .
625 line i would say there's still a lot of ways to display to sets of this system .
The smaller screen size of the 405 line sets is something i like we as you know in Australia never really had tiny sets at that stage we started television we copied the U S sets size not the Uk .

Then there is the small problem of source material, after a while a test-card becomes a tad boring. There is a case for a 625-405 version.


Well not a problem to Trevor and i the good thing is the PC does the signal and the video or images to display even a camera live either system is a click of the mouse away .

A revision of the SSTV-625 convertor I made a few years ago may be in order....the output side (625 read mode) is already done and shouldn't require any modification (I think). The input side (now 405 write) would require significant work, both in hardware and software. A small plus-point is there's no requirement for a demodulator, simply baseband 405 in.


Any new systems converter is interesting, reminds me i still have a 625 to 525 line visa versa pal to NTSC or NTSC to PAL from the video tapes days

Steve A.

Maybe just a 625-405 down-convertor is actually all that's needed? Do we need to convert 405 to 625? In other words, for those that own a WC-01 what is its primary use? For those that would like to own one, what major use would you use it for?


Yes i think there's a lot of things that still exist that output 625 line but near to nothing for 405 line so would be of interest to those new set collectors or any one who want the video signal

As ever, specifying a suitable video A-D is a hurdle....but as mentioned elsewhere/previously, the TLC5540 appears suitable....though not available in a DIL package, only SO (useable...just) or TSSOP (unusable).


OH yes some times those things can be too small ! tssop even if you had a micro scope i do ; ) and pin for an soldering iron who has the steady hands to get the soldering right ,I don't know of the TLC5540 are you planning a systems converter around this IC ? the idea of this is always interesting .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: The 405 line monitor MK2

Postby Steve Anderson » Sun Aug 14, 2022 8:31 pm

Harry Dalek wrote:I don't know of the TLC5540 are you planning a systems converter around this IC ? the idea of this is always interesting .


The TLC5540 would at this moment be the video A-D of my choice, the right sort of price, the right specifications, shame that it's only in SO or TSSOP packages. That appears to be it's only downside. Though I do have some A-D converters that may be up to the task, That's forgetting the CA3306...even though I have a stock of them...though not that many...maybe a dozen or so...

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Re: The 405 line monitor MK2

Postby Klaas Robers » Mon Aug 15, 2022 10:54 pm

As far as I remember, the 405 line system had a picture ratio of 4 : 5, while the 625 (and 525) standards have 3 : 4. I don't know how the BBC tackled that problem when they went over from 405 to 625 (PAL colour). I know they had an (all tube and storage capacitor) scan converter from 625 to 405 lines. I think they simple cut off a band left and right. Because the 625 colour programs also were sent in 405 line black and white.
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Re: The 405 line monitor MK2

Postby Dave Moll » Tue Aug 16, 2022 5:50 pm

Initially, yes, a 5:4 ratio was used on 405 lines in the UK, but it was changed to 4:3 long before the introduction of 625 lines.
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Re: The 405 line monitor MK2

Postby Klaas Robers » Wed Aug 17, 2022 8:02 pm

Did this imply that everybody had to increase the picture width on his 4:5 TV, so it had more overscan? May be while looking to the test chart in order to see a true circle again? And was that communicated via news papers and magazines in the UK?

Yes of course, they could also decrease the picture height and see a black bar above and below the displayed picture.

Was that really done? I have never heard of such a thing. And it is very exceptional to change a consumer standard while every thing is up and running.
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Re: The 405 line monitor MK2

Postby Steve Anderson » Fri Aug 19, 2022 1:13 pm

I've heard about this aspect ratio change from a number of sources so there has to be an element of truth about it. When this occurred I don't know, though I haven't done any research to find that out.

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Re: The 405 line monitor MK2

Postby Dave Moll » Fri Aug 19, 2022 5:18 pm

According to https://405-line.tv/tv-history/, the change officially took place on 3rd April 1950.
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Re: The 405 line monitor MK2

Postby Harry Dalek » Wed Aug 24, 2022 3:50 pm

That's interesting i would of thought the aspect ratio is due to picture tube shape ,the original was round so either way your never going to fit it in without leaving gaps by the 50s 4.3 tubes bit more common, a square tube German invention in the late 30s with i think the E1 Table top TRF one channel Television for Paul Nipkow Channel Berlin first 4.3 or 4.4 ? picture tube 441 line .

My Lm1881 replacement or i should say 10 never know arrived today 8) this time it will have its own stable supply .
I will get back onto it this week .
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