The Mongrel

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Re: The Mongrel

Postby Harry Dalek » Mon Nov 08, 2021 9:09 pm

Steve Anderson wrote:If I had got 10-100V peak-to-peak out of that I would have thought, "I guess that's about right." But just 1.5V or so - I'm sure there's something not quite right...is the frequency anywhere near what you're expecting?

Having no experience with this arrangement I'm not much help...

Steve A.


Me too Steve learning as i go tell you what i am more happy with the Russian Phantastron time base oscillators than this larger one i feel it drifts more ,the small tubes its really stable may be i picked the wrong tubes for the circuit but i think the larger tubes do give a better waveform ramp as in shape ,getting the frequencies for sure free running a little drifting might be a little voltage frequency sensitive ..old 555 timer is like that .
Perhaps a dual pentode and triode might be a better idea every thing nice and close /at the moment 2 pentodes and a dual triode doing the job .

Yes if you are seeing what i am with such a small waveform i think the problem is the 100k resistor for the size control i will redo the test other side of it .
When i built the circuit again with the little Russian tube i left the 100k resistor out i am thinking its reducing the the waveform only way to make sure redo the experiment at the cathode of the triode pin 8 .
I was thinking before i started this the valve time base might just about drive a deflection plate ...always a reason so i will look when i have time at what really is coming out of those tubes .
Always of help Steve always good to see what you think about this stuff .
When i am off work i will do all this again later in the week and if any thing should give better results this time how much find out ; )
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Screen 00000.bmp
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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 Mongrel

Postby Harry Dalek » Fri Nov 12, 2021 9:04 am

Steve Anderson wrote:If I had got 10-100V peak-to-peak out of that I would have thought, "I guess that's about right." But just 1.5V or so - I'm sure there's something not quite right...is the frequency anywhere near what you're expecting?

Having no experience with this arrangement I'm not much help...

Steve A.


Finally Steve had time to double check the ramp at the cathode follower and my thoughts were correct about the 100k resistor and your peak to peak guess looks correct too .
readings on the screen picture 10 volts per div , p to p and 91v this looks more like it !

With the oscillator there seems to be a bit of drift on free running i think it could be a pot i am using to readjust it never good these mechanical controls only a matter of time before they all end the same .

Any case at least a step forward
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DSCN6736.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 Mongrel

Postby Steve Anderson » Fri Nov 12, 2021 12:05 pm

Harry Dalek wrote:...readings on the screen picture 10 volts per div , p to p and 91v this looks more like it !

Agreed. Are you using the probe in x10 mode? If so you should be able to get the whole waveform to fit vertically within the screen, rather than 'chopped off' at the top.

If the 'scope is set for 10V/division and using the probe in x10 mode, effectively that becomes 100V/division, almost a kV will fit vertically without 'chopping'.

Steve A.
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Re: The Mongrel

Postby Harry Dalek » Fri Nov 12, 2021 7:38 pm

Steve Anderson wrote:Agreed. Are you using the probe in x10 mode?


Double checked in 10xmode yep

If so you should be able to get the whole waveform to fit vertically within the screen, rather than 'chopped off' at the top.


i pretty much didn't want to adjust any thing in case the p to peak would read false but i forgot to tell you and take into account my self ! i had to use a 2.2m resistor to drop the wave to show as is with out adjusting the scope .so this would of effected the p to p reading ? if so i will do it again .

If the 'scope is set for 10V/division and using the probe in x10 mode, effectively that becomes 100V/division, almost a kV will fit vertically without 'chopping'.

Steve A.
[/quote]

mmmm i wonder why its not ,digital scopes in some ways are more tricky than analog in some ways i wish they left the controls old style ...i would think now every different digital scope will have their own way of adjusting every thing same idea but different menu controls standardization has its benefits .

Hooking the ramp to the defection amplifier no real luck i do get a line if i just ground the cathodes via a 1k or so resistor at it then lets me move the position of the line a bit but doesn't seem to work on high negative idea on these triodes .
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 Mongrel

Postby Harry Dalek » Sat Nov 20, 2021 2:26 pm

Klaas Robers wrote:Harry, you should realize yourself that the deflection plates of a CRT should be steered both, and in opposite phase. For a constant focus it is needed that the induced 'mean' voltage at the position of the deflection plates is constant, not changing with the deflection voltage. That will say both plates should contribute to the deflection, one in positive way, the other in negative way. So the idea of feeding just one plate with a saw tooth signal, and the other with a fixed voltage that you can adjust for centering control, is not Ok.

If you feed just one plate, you will see that the spot may be focussed at beginning edge of the screen, but unsharp at the end side. Adjusting the focus control will not help you; if you make it sharp at the end side, then it will be unsharp at the beginning side. I re-realized myself these facts when yesterday I jumped into the circuit diagrams of one of my Heathkit waveform / spectrum displays, the SB-620. It shows horizontal deflection problems.......


Ever since Klaas posted this advice i have been on the task no giving up !
Any case the answer to the best waveform and answer to the best peak to peak match was this circuit below just a few volts off each other and just a little change to the idea i was using which just needed an extra dual triode vacuum tube and pretty much takes care of the deflection amplification as well .
The scan is nice and crisp now more than enough deflection over deflection really ,problem now is i don't have position or size control using this ,size of the ramp increases and decreases both original and inverted ramp with voltage supply to the circuit so not so much a problem here that can be adjusted , position might have to be done the original way by control of Dc voltage on the deflection plates .
Below circuit using a 12AT7 or 12AU7 numbers rubbed off so need to double check here
Screen 00040.jpg


Frame ramp below 6hz didn't adjust it up to 12 hz 5v off each other Peak to peak
DSCN6738.JPG


LIne ramp
DSCN6760.JPG


Raster with above peak to peak voltages
DSCN6768.JPG
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DSCN6765.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 Mongrel

Postby Steve Anderson » Sat Nov 20, 2021 6:04 pm

The vast majority of electrostatically deflected CRTs are designed to be driven with a 'push-pull' arrangement, both in the X and Y axis. In other words when one plate is driven positive the other goes an equal amount towards negative. Therefore the average voltage stays constant. If it doesn't the focus suffers as Klaas mentioned above. This is evident in the 1CP1 1" display I built some years ago, and this little CRT is designed for non-symmetrical horizontal drive...i.e. it effectively has only one horizontal deflection plate.

However, even considering the design was supposed to allow for this fact, it still does de-focus to some extent at the extremes of horizontal deflection...enough to be noticeable. But for what it's intended usage was it's good enough. (Monitoring AM modulation linearity in transmitters).

The 1CP1 (aka DH3-91 in Europe).

Steve A.

1cp1advt.jpg


DH3-91.pdf
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Re: The Mongrel

Postby Harry Dalek » Sat Nov 20, 2021 7:44 pm

Steve Anderson wrote:The vast majority of electrostatically deflected CRTs are designed to be driven with a 'push-pull' arrangement, both in the X and Y axis. In other words when one plate is driven positive the other goes an equal amount towards negative. Therefore the average voltage stays constant. If it doesn't the focus suffers as Klaas mentioned above.


Hi Steve
I found doing this really hard at first i tried the ramp inverter below the second half of the triode it pretty much inverted the ramp but it was at 17v peak to peak and normal up around 94v try as i might i could not even them out apart from at a lower 9v each which was pretty unimpressive or useful must of been some evening out in the deflection amplifier but using to many valves for my liking
Screen 00058.jpg
Screen 00058.jpg (82.61 KiB) Viewed 1693 times


Any case every thing i tried the circuit in the last post was an easy fix i just had to try it seems to be giving a better ramp than displayed in the original for both ,least i have something to work with now ,i was starting to think i named this project monitor correctly :wink:

This is evident in the 1CP1 1" display I built some years ago, and this little CRT is designed for non-symmetrical horizontal drive...i.e. it effectively has only one horizontal deflection plate.

However, even considering the design was supposed to allow for this fact, it still does de-focus to some extent at the extremes of horizontal deflection...enough to be noticeable. But for what it's intended usage was it's good enough. (Monitoring AM modulation linearity in transmitters).

The 1CP1 (aka DH3-91 in Europe).


So more a scope type display ,i always wondered if things like this CRT with one horz deflection plate or a magnetic crt with none could be electrostatically deflected from plates on the out side of the CRT the ones we play with tend to be very sensitive ,every one has seen the class experiments with a glass rod charged up with a cloth rubbing and placed near a crt one of those things never know till you try .

The defocusing of the crt raster line just using one deflection plate is something i didn't under stand and still a little unclear about looking at past gos using your deflection amplifier one side is feed by the ramp and the other is voltage adjusted the ramp only is feed to one side of the deflection but its still gives a sharp raster i suppose thats what confuses me but learn as i go reason i do so many crt projects to learn /
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 Mongrel

Postby Steve Anderson » Sun Nov 21, 2021 1:15 pm

These deflection amplifiers are known as a 'Differential Amplifier'. In its simplest form, as used many times here, it comprises two active devices, (standard transistors, FETs or valves/tubes). Additional devices can be added to improve performance, but for what we do here the simple versions are generally good enough.

There are many references to this arrangement on the 'net, but as always I point to what I consider the 'Bible of Electronics'. Its first edition was published in 1980 and the current 3rd edition can still be bought from the usual book sources. It's not a dry 'thesis-style' tome, it is actually quite readable! I consider it one of the best investments I have ever made.

"The Art of Electronics", By Paul Horowitz and Winfield Hill, ISBN10 0521809266 or ISBN13 9780521809269. This should be considered as important as a soldering iron, it really is an essential tool. My only wish is that it were published when I was studying. Every workshop should have, no, MUST HAVE a copy. (I have no connection with the authors or publishers).

However, as with everything connected with electronics it quickly goes out of date. But it's the principals presented and how to apply them that is the foundations upon which stuff is built. When you see a circuit that calls for a now virtually obsolete BC108, you simply replace it with its modern equivalent, a BC548. Armed with this knowledge you'll be able update, improve and modify older circuits and ideas with confidence. (This is starting to read like a commercial, it's not meant to be one though).

If possible borrow a copy from a library first just to see if you agree with my assessment. There is a degree of maths involved, but don't let that scare you, it generally is quite simple and it's not essential if you don't want to tackle it.

Steve A.

P.S. Make sure you get a genuine copy, there are counterfeits 'out there', heed the warning on the second link below...

https://en.wikipedia.org/wiki/The_Art_of_Electronics

https://artofelectronics.net/

https://en.wikipedia.org/wiki/BC108_family
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Re: The Mongrel

Postby Harry Dalek » Sun Nov 21, 2021 2:48 pm

Steve Anderson wrote:These deflection amplifiers are known as a 'Differential Amplifier'. In its simplest form, as used many times here, it comprises two active devices, (standard transistors, FETs or valves/tubes). Additional devices can be added to improve performance, but for what we do here the simple versions are generally good enough.


Yes try again as i might i could not get the valve version to cooperate so that will have to be on my to do list as i will be playing with valves for a little while yet ,but apart from your experiment at designing one i can't say i have seen another valve version (transistor yes a few ) but vacuum tube nope ! or i would of used it as the transistor version worked so well .
I am happy enough with results today to drop the raster size
DSCN6810.JPG

DSCN6783.JPG

DSCN6787.JPG


There are many references to this arrangement on the 'net, but as always I point to what I consider the 'Bible of Electronics'. Its first edition was published in 1980 and the current 3rd edition can still be bought from the usual book sources. It's not a dry 'thesis-style' tome, it is actually quite readable! I consider it one of the best investments I have ever made.

"The Art of Electronics", By Paul Horowitz and Winfield Hill, ISBN10 0521809266 or ISBN13 9780521809269. This should be considered as important as a soldering iron, it really is an essential tool. My only wish is that it were published when I was studying. Every workshop should have, no, MUST HAVE a copy. (I have no connection with the authors or publishers).


Well i have never heard of this book it seems to be in pdf form is this book correct
Art of Electronics 3e.pdf
(29 MiB) Downloaded 91 times

i haven't had a good look at it yet but will after this posting .
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 Mongrel

Postby Steve Anderson » Sun Nov 21, 2021 4:14 pm

Yep Harry, that looks very much like it. A good find, the printed version is around US$50 plus shipping.

As I mentioned, don't be put off by the maths, it still makes a lot of sense without it...

Steve A.

P.S. Even those confident with starting with a blank piece of paper and designing their own circuits could find this a useful 'refresher course'. As the first edition was published over 40 years ago, and I assume the authors are now retired, I doubt we'll ever see a 4th edition. Who could run with this baton and continue where these guys eventually leave off? Anyone?
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Re: The Mongrel

Postby Harry Dalek » Sat Nov 27, 2021 8:06 pm

I had a go at making a sub miniature vacuum tube version along side the miniature version of what i am doing pretty identical apart from the voltage has to be adjusted down to the tubes working voltages bit harder to even out the peak to peak results than the other tubes but is what it is making due with tubes i have /
Attachments
DSCN6817.JPG
DSCN6816.JPG
DSCN6818.JPG
DSCN6819.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 Mongrel

Postby Harry Dalek » Sun Dec 12, 2021 2:05 pm

I am happy now with the scanning and back from a holiday in Sydney my thoughts are turning back to the syncing side of it what i am using at the moment will work but to me looking at the waveform its not clipping the sync well enough for my liking so time to do some more reading and experimenting , this PDF is rather good on the subject .
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Philco-1952-06.pdf
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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 Mongrel

Postby Harry Dalek » Sat Jan 15, 2022 3:20 pm

Thought i would get stuck into finishing off this enough to at least display .
Not one of my best monitor go's perhaps my worst but the goal was to make a valve NBTV monitor and learn a bit more .
So first job today was get beam modulation going and just use a transformer to passive modulate the control grid results were below works now on to adjusting the ramp generators but rethinking the syncing as the circuit i was using was effecting the ramp
DSCN6852.JPG

Manually adjusting the ramp generators with no syncing result below

Now i am using a EF80 same as 64SPT 6BX6 for the ramp generator had a hell of a time trying to sync these via the trigger connection shown ,it effected the ramp shape size ended up that the S connection below pin 6 does the trick with out effecting the Ramp size shape only syncing .
Screen 00007.jpg
Screen 00007.jpg (29.87 KiB) Viewed 1096 times

phan008.png

Start of syncing results were first hooking up and trying the syncing to line sync connection pin 6 S connection ,upside down Benny hill but line Ramp is in sync

Next try both line and framing so are both working .

I think due to no regulation of the of the circuits DC supply any swing in the line voltage can knock the ramp oscillator's off frequency as they are voltage sensitive so a slight adjustment is needed when it happens .
This was a Learning exercise knock up some thing with a very limited idea how to do it from scratch, bit of research trial error and do it with minimum solid state which i kept to the 1000v diodes in the power supply only .
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DSCN6875_x264.mp4
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DSCN6888_x264.mp4
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DSCN6899_x264.mp4
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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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