The Cyclops a Vidicon project

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Re: The Cyclops a Vidicon project

Postby Harry Dalek » Wed May 30, 2018 8:59 pm

Update on whats going on .
Well first chance to test the head amp today ,but still no Target signal detected so some thing else is still not Cooperating.
All voltages seem ok on their adjustments ,i did find i have duplicated the 100k resistor from the target HV variable supply also on Richards labguys head amp circuit so 2 100k resistors now in series ,i will look into that tomorrow removing or by passing one ,i recall the target voltage did not have much control prtetty much set to top setting when it was working ,so thinking this could be whats up .
Anyway i will have another try tomorrow .
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 Cyclops a Vidicon project

Postby Harry Dalek » Fri Jun 08, 2018 6:46 pm

Well i did hope to have better news this post on this project but i am stumped as to my vidicon is not cooperating any more :roll:
Been pretty much looking at the head amp side of it for a while ,but if there is no signal at the Target ring of the vidicon and this makes things worse ,trying to think of things i have missed or changed or might be damaged.
I have first double checked the Tube connections .
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This is all correct no different to when it was working .
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Checking the voltages they were the same also but i have now disconnected the variable load resistor and 100k resistor across the the positive HV supply since the tube data did say it can be run higher .
ScansEX80055.pdf
The XQ1290 vidicon data sheet
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so at the moment the results are
G1 0 to negative 114
G2 positive 272 to 365
G3 at positive 367
G4 at Positive 441
Target positive 0 to 98 volts
The power supplies voltages still look all good ,i looked also into the deflection side as i could see with out this working correctly there would also be no Target signal .
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I have some low ohm resistors across the deflection coils below where scope reading taken...first is Horizontal then vertical .
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i also put a cap across the vertical and cleaned the sawtooth a touch better
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But any case no results at the target by passing the head amp and checking just with the scope it has still no light detection.
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Using the above circuit for the Target voltage and signal output ..the 1 meg resistor seems common to most vidicon circuits and did work before /
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 Cyclops a Vidicon project

Postby Klaas Robers » Sat Jun 09, 2018 7:13 am

try to insert a square wave of say 10 kHz, 1 volt through a 1M resistor to the input of the preamp. That should become visible at the output of the amp. Any way there should be some output of the preamp, noise, picked up signals, but the square wave is a suitable test signal.
No output: preamp not working,
Yes output, something else not working.
Insert the signal at the target contact, without the vidicon in the deflection yoke.
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Re: The Cyclops a Vidicon project

Postby Harry Dalek » Sat Jun 09, 2018 8:50 am

Klaas Robers wrote:try to insert a square wave of say 10 kHz, 1 volt through a 1M resistor to the input of the preamp. That should become visible at the output of the amp. Any way there should be some output of the preamp, noise, picked up signals, but the square wave is a suitable test signal.
No output: preamp not working,
Yes output, something else not working.
Insert the signal at the target contact, without the vidicon in the deflection yoke.



Thanks for the reply there Klass,I have made a few preamps and give that idea a test I did try some thing similar with the last one it was picking up the signal generator even when I put the wire from the generator close to the input but I will give them a test again and show you the best .
Yes thanks pretty logical no output it's not up to the job,I was having the problem where it seemed to work but not on the tube ,yesterday I took the camera out to my shed where my better scopes are and had a look direct at the out put of the target there was a signal but nothing that made me think it was due to light sensitivity of the target ,I did get a scope signal touching the target glass plate due to that and I can see adjusting the target and grid one voltages effects the signal.
I will give the advice a go KLaas and show you the results next 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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Finally got it back !

Postby Harry Dalek » Sat Jun 09, 2018 5:18 pm

Thanks Klass for the last advice as it did stear me in the right direction.
I first tested the preamps i had made and tested them all with a square wave sine wave and white noise up to 20 khz came down to the Late Peter Yanczer's pmt camera preamp the circuit had wide frequency range to the end i also noticed there was no distortion in the type of signal wave form i used seeing result on its output ....i used a MPF102 as the FET
PMT_Video_Amp (1).jpg

Circuit below used
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Well all looked good here it was very sensitive did not distort the waveform and had the bandwidth,i found with the others there was some distortion to the wave form and frequency cut off after 10khz quickly.
So i hooked up the winner back up to the Vidicon and the bugger worked right away ...there was the Target circle,...... 2 weeks or so of head scratching gone :wink:
i noticed the light sensitivity right away on the scope mixed the video with the sync and viewed the result on Big picture ,i turned off the magnetic focus as i knew i would see the Target circle if it worked result below .
Working at 32 line here ,a very small result to show but it is massive to have the light detection back.
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I will look into your procedures mentioned Klaas now i have this back .
Attachments
DSCN9746.JPG
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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 Cyclops a Vidicon project

Postby Andrew Davie » Sun Jun 10, 2018 12:21 am

I just watch in the background, in complete awe of your skills. Keep up the good work.
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Re: The Cyclops a Vidicon project

Postby Harry Dalek » Sun Jun 10, 2018 9:00 am

Andrew Davie wrote:I just watch in the background, in complete awe of your skills. Keep up the good work.


Thanks Andrew ! i did not want to give up more so since i had it working before . :roll:
In some ways its good this problem happened to me as i wanted to make the pre amp also in stead of using a already made one ,and its taught me what to do to get the hardest part of the camera working, ended up being just 2 transistors thanks to Peter Yanczer !
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Last edited by Harry Dalek on Sun Jun 10, 2018 11:14 pm, edited 1 time in total.
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 Cyclops a Vidicon project

Postby Harry Dalek » Sun Jun 10, 2018 10:38 pm

Didn't have much time today but i have been itching to do a light detection test .
i can see i have to adjust swap the deflection coil connections but it is on its side at the moment ....doing some camera tests i am upside down having a quick look into the camera lens here in this video below .
i just adjusted it enough to make things out via working out the focus distance ok for 32 line and not using all the frame area yet .
It's still touchy as to how big the screen size is to focus i will try Klaas your suggestion on reducing the deflection voltage current ,i can see the vidicon is a fussy beast !
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Output_Merge(2).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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Re: The Cyclops a Vidicon project

Postby Klaas Robers » Mon Jun 11, 2018 8:24 pm

Harry, you should realize yourself that if you decrease the deflection current, that you shrink the scanned area of the target, so your picture is made larger..... This is somewhat contra intuitive, but if you realize what you are doing, it is also logically.

This is contrary to a picture tube, where the picure gets smaller if you decrease the deflection currents.
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Re: The Cyclops a Vidicon project

Postby Harry Dalek » Mon Jun 11, 2018 9:04 pm

Klaas Robers wrote:Harry, you should realize yourself that if you decrease the deflection current, that you shrink the scanned area of the target, so your picture is made larger..... This is somewhat contra intuitive, but if you realize what you are doing, it is also logically.

This is contrary to a picture tube, where the picure gets smaller if you decrease the deflection currents.


OH yes i see what you mean Klass ! i understand now what you were suggesting .
The scan area of the Vidicon Target face you are using with a smaller deflection scan a smaller percentage of the Target area is used ,i would think its scan area is mean't to fit in most of the Target area? ,i can see this would effect the screen size without effecting focus .
I have been trying to do this my mistake via the focus coil .
I wonder how small this can be used as i i would think as in a photo if you blow up the image you start to see the particles limiting factor being here how fine the scan beam can be focused so the detail would begin to be lost with a tiny deflection scan ? so a tiny scan to small would show the effect of a out of focus image also don't you think ?
But any case yes logical .
I will look into it next time i can play with it .
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 Cyclops a Vidicon project

Postby Steve Anderson » Tue Jun 12, 2018 2:50 pm

Yep Harry, you've got concept right. It's similar to enlarging a photographic negative, If you print a whole 35mm negative to 8"x10" you're unlikely to see the grain (unless it'a a really high speed film). If you enlarge just a small portion of that negative the grain (the silver halide particles in the emulsion) become more obtrusive.

If you look at the phosphor on a monochrome CRT through a magnifying glass you can see the particles of the phosphor. The target of a camera tube is much the same, different compound and smaller in particle size, but it still has 'grain'.

Though it's unlikely to be noticed at the number of lines we generally are talking about here.

Steve A.

The same concept applies to digital cameras. If your camera is 12 megapixels (3000 x 4000) and you crop the image to 300 x 400 you can see each individual pixel - sort of 'digital grain'.
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Re: The Cyclops a Vidicon project

Postby Harry Dalek » Tue Jun 12, 2018 3:52 pm

Hi there Steve
i suppose the top of the range vidicon's have the finest grain if that's the right word or light sensitive chemicals on the Target .
Read some where that there are blemishes are on the Target area from time to time ,i was thinking you could reduce the deflection scan size depending where they are on the Target area perhaps you could move the scan away from any ...same idea for a crt if you don't mind where the smaller scan is on the screen.
Here so far I have been just using part of a 32 line frame ,i will move up to 64 line when i do the first wav file recordings ,i will just follow Klaas's advice on the deflection side of things first.
These image tubes are interesting things still about on ebay a lot of eastern European by the looks of it .
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 Cyclops a Vidicon project

Postby Klaas Robers » Wed Jun 13, 2018 9:53 pm

Vidicons have no grain, the layer is continuous. But they may have blemishes, spickels and/or unequal dark current (that is wat you see in total darkness, with the hood on the lens) on the target. The sharpness, definition, is almost always good enough for 625 lines.

When a vidicon is looking at a fixed picture for a long time (days, weeks, months) the picture may be "burned" in the target. That is thee dark current in which you still see the previous picture. This is when a vidicon camera is used in a fixed position for surveyance. This disappears slowly (days, weeks, months) when the vidicon is used under changing conditions, or aimed fixed at a white area. So old, used vidicons can have quite some imperfections.

And don't forget, you have TWO focus controls,
- one is the optical focus of the lens onto the target,
- two is the electron beam sharpness adjusted by the current in the focus coil.
Both should be well adjusted.... for 625 lines.

Vidicons are not linear, they have a kind of automatic gamma correction. Thsi is contrary to the plumbicons, which are linear. For a plumbicon camera you need a gamma correction circuit, for a vidicon used in the same camera you can switch off the gamma correction.

Good luck!
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Re: The Cyclops a Vidicon project

Postby Steve Anderson » Thu Jun 14, 2018 7:15 pm

Klaas Robers wrote:When a vidicon is looking at a fixed picture for a long time (days, weeks, months) the picture may be "burned" in the target.


Yep, I think most of us have seen that from old security cameras using tubes. It may well go away after a long time of active use afterwards but by then the tube is probably getting toward the end of its life anyway...the question is...why was it replaced in the first instance?

Steve A.
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Re: The Cyclops a Vidicon project

Postby Harry Dalek » Thu Jun 14, 2018 7:34 pm

Well i was not expecting to be in the same situation as i was a few days ago but at least this time i witnessed the decline before i lost the Target signal /
I think its one of the preamp Transistors i will pull out the preamp and test it as before tomorrow ,pretty much at the start i had very good results images and slowly i noticed the target image became blurry and and then slowly the Target image signal disappeared .
I tested the voltages and deflection all this is the same looks fine ,I sort of wish i wrote down the adjustments before this happened a mistake i will not do again .
Just when i was ready to do some tests and recordings arrr nothing go's to plan :roll:
Klaas Robers wrote:Vidicons have no grain, the layer is continuous. But they may have blemishes, spickels and/or unequal dark current (that is wat you see in total darkness, with the hood on the lens) on the target. The sharpness, definition, is almost always good enough for 625 lines.


I would not be able to see this yet as i am only trying 32 and when i can 64 lines so far but i will look out for it on the higher line rates .

When a vidicon is looking at a fixed picture for a long time (days, weeks, months) the picture may be "burned" in the target. That is thee dark current in which you still see the previous picture. This is when a vidicon camera is used in a fixed position for surveyance. This disappears slowly (days, weeks, months) when the vidicon is used under changing conditions, or aimed fixed at a white area. So old, used vidicons can have quite some imperfections.


I noticed the ghosting effect with an 80's camera i used to have ,i don't like the idea of doing that to the camera but see its a problem the old vidicon tube has ,i am glad to hear some times you can rid the Target of the burnt in image ...i know just instant pointing it at the sun its on there for good .
So yes i have noticed it too Steve and klass

And don't forget, you have TWO focus controls,
- one is the optical focus of the lens onto the target,
- two is the electron beam sharpness adjusted by the current in the focus coil.
Both should be well adjusted.... for 625 lines.


My tube has electrostatic as well as the other 2 but i see the magnetic focusing is more effective seeing it working .

Vidicons are not linear, they have a kind of automatic gamma correction. Thsi is contrary to the plumbicons, which are linear. For a plumbicon camera you need a gamma correction circuit, for a vidicon used in the same camera you can switch off the gamma correction.

Good luck!
[/quote]

Well that's good one less thing to think or worry about but now i am back to a little head scratching ,least by the end of this it will be able work out a problem quickly .
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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