NBTV Television Analyst

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Re: NBTV Television Analyst

Postby Harry Dalek » Mon Apr 06, 2020 8:40 pm

Steve Anderson wrote:Harry, if you're using the same type of CRTs as before (and two of them) why not use exactly the same power and deflection arrangement as before. It worked, why go through all this again?...unless I've missed something...there is only so many ways this can be done....a bit like skinning a cat....

Steve A.


Hi Steve

I want the circuit to your design Steve as is and same sort idea 2 CRT of the same type as last time but for a different use ...all i am doing here different as a challenge is to use this Nice Transformer, its only down side is it has a higher voltage than i am used to ... i am a curious bugger .
Just trying to match the voltages to the 3BP1 design ,i also have another and this will come in handy to learn how to do this ...there's lots on how to bring a voltage up not so easy to bring it down ...i find it interesting and challenging....and i have never tried this before well sort of as i did use the dropping of the high Negative on The Binocular project but via your multiplier chain perhaps not elegant but it worked
I could just as you think cable a standard known AC voltage in but i want it a stand alone unit and i like making things from scratch so a few reasons ...easiest way is not one of them !
If the Transformer was similar to the last a 3 wire i would keep the AC DC side of it to how we did it before but i was thinking due to the voltage size a simple voltage double circuit would be ok this time ..well least that was my thinking use some thing that would work with this transformer , your HV negative supply circuit is more a multi stage multiplier i am not sure and i should of asked how it would of coped with Ac voltages like this .Any case the Negative supply works as is now ,just trying to work out the positive side needed for powering the anode and deflection amplifiers .
I have a fair few CRts very lucky to have them ! getting most of the 3BP1's out of the way in projects like this and the latest ,i would hate it getting to the end of my life and know i never used them ..so that's another reason , just i enjoy using them and i love CRT's ,very much so the electrostatic deflected type ...for me its just fun to come up with idea for them .
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Re: NBTV Television Analyst

Postby Harry Dalek » Tue Apr 07, 2020 7:55 pm

Klaas Robers wrote:Harry, you can do better, this will not work.
It depends on what you want to get.
- If you want to get +1100 volts, then you should remove the capacitors going downward to the diodes, and replace them by a wire,


Sorry Klaas i get your circuit change now i will give it a go 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: NBTV Television Analyst

Postby Harry Dalek » Wed Apr 08, 2020 6:03 pm

I finished the changes to the positive side of the HV power supply Klaas suggested ...works fine
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Still a bit high results on the main output capacitor i can tap and or adjust the capacitor chain my main thinking at the start to get the voltages i want .

But got me thinking about was it possible to adjust the AC side of the power supply and having played around with the Saturable reactor idea before i gave it a go.
Was pointless to adjust the 240v side as i need the low AC as is ,so just worked on the 800v AC side .

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And it sure does work and even more simple way than the above image ,you don't need the DC control voltage it still works in the way mentioned below

The test transformers were tiny the ones shown below ,with the primary of the little transformer in circuit it drops the HV Negative from 2070v to 1690v
that's with the secondary open circuit ...close the secondary windings voltage jumps back up to 2070 ..put a pot or trimmer on the secondary you can adjust the out put voltage from 1690 to 2070v no problems at all no heating problems there is very little voltage on the secondary what so ever .

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I tried 1 small transformer it gave a drop to 1760v 2 small in series 1610v the larger one and a small in series 1550v so with that last idea with 2 pots on both secondaries you can adjust the voltage from 1550 to 2070 volts .

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I might try it with a variable dc power supply as it should be possible to get any range you want ,i suppose since we don't use HV much these days these ideas are forgotten . ?
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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: NBTV Television Analyst

Postby Harry Dalek » Thu Apr 09, 2020 2:26 pm

I have finished the power supply board tested with and with out loads this thing will have no problems powering both crts ...moving on to the crt circuit i will not power it up till i have deflection of some sort .

Also tossing up the idea using a smaller crt for the flying spot scanning side more for room .

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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: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 10, 2020 6:02 pm

Work has moved on to to finishing both CRT power supply circuits i did change my mind on the Flying spot scanner CRT its now a VCR139A again mainly for positioning room later with the PMT ...so changes made to the design for powering it ... once again using the work from Steve A..
I am now thinking can i get away with using the same deflection amplifiers for the CRT plates well it did work for the The Binocular project but that was using 2 3BP1's here i suspect because the tubes are different sizes deflection size will be different ..well so long as the smaller tube can scan and it can be displayed viewable size on the 3bp1 would be ok save parts as well .

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3BP1 CRT 2 (1).gif
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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: NBTV Television Analyst

Postby Klaas Robers » Fri Apr 10, 2020 6:29 pm

In principle you don't need the video input for the flying spot tube, as it will display only a white field. However, you might like a fly back suppression, as that gives just rubbish in the video signal from the PMT.

Good luck!
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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 10, 2020 8:22 pm

Klaas Robers wrote:In principle you don't need the video input for the flying spot tube, as it will display only a white field. However, you might like a fly back suppression, as that gives just rubbish in the video signal from the PMT.

Good luck!


I have never built in flyback suppression i have not tried the switching i have to admit ,i noticed on the Thylacine monitor which is Magnetic deflected its flyback retrace is very noticeable can't say i have noticed it on a electrostatic CRT is this because its fly back is quicker than a perhaps sluggish magnetic type ?

ON The PMT does magnetic field effect its working ? i was thinking of lining the tubes up face to face i mean but the PMT might be close to the transformer .
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: NBTV Television Analyst

Postby Steve Anderson » Sat Apr 11, 2020 12:19 pm

Good point Harry, I've not thought of the possibility of PMTs being influenced by external magnetic fields. Never noticed the effect myself but electrons moving in free space will be 'modulated' by a magnetic field - the same would in principle apply to ordinary valves/tubes. Best insurance is to keep transformers and the like away from any vacuum-based device.

Steve A.
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Re: NBTV Television Analyst

Postby Harry Dalek » Sat Apr 11, 2020 3:39 pm

Steve Anderson wrote:Good point Harry, I've not thought of the possibility of PMTs being influenced by external magnetic fields. Never noticed the effect myself but electrons moving in free space will be 'modulated' by a magnetic field - the same would in principle apply to ordinary valves/tubes. Best insurance is to keep transformers and the like away from any vacuum-based device.

Steve A.


I am still away's from working on the PMT side but does not stop me thinking of the positioning :wink: Yes the magnetic field next to a PMT i was wondering about .
I have swapped FSS CRT to a VCR139A cuts the size down a touch so i could have the PMT facing it . depending on the PMT the transformer would be perhaps behind worst case about 2inch to one side any case i might test it to see either way when i get around to that time in the project .

Have to also remember the VCR139A has a 4 volt heater not 6.3v like the 3bp1..

I have finished the defection amplifiers ,next the sawtooth generators ,i will make sure i have deflection on the CRTs before i think of powering them up.
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: NBTV Television Analyst

Postby Steve Anderson » Sun Apr 12, 2020 12:55 pm

Harry Dalek wrote:I have finished the defection amplifiers ,next the sawtooth generators ,i will make sure i have deflection on the CRTs before i think of powering them up.

Sage advice to others Harry. As usual check each sub-circuit one-by-one, wire them altogether as required, check they all still work as advertised. Then add the CRT with NO VOLTS on the heater, check again - nothing should have changed unless there's something wrong with the CRT - an internal short perhaps? If happy - apply heater volts, hope and prey!

Steve A.
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Re: NBTV Television Analyst

Postby Harry Dalek » Sun Apr 12, 2020 1:50 pm

Steve Anderson wrote:
Harry Dalek wrote:I have finished the defection amplifiers ,next the sawtooth generators ,i will make sure i have deflection on the CRTs before i think of powering them up.

Sage advice to others Harry. As usual check each sub-circuit one-by-one, wire them altogether as required, check they all still work as advertised. Then add the CRT with NO VOLTS on the heater, check again - nothing should have changed unless there's something wrong with the CRT - an internal short perhaps? If happy - apply heater volts, hope and prey!

Steve A.


Yes one thing at a time for sure....it is a bit easier as i have worked on these a few times but seeing it come together as circuit's its pretty complex really just easier for me as i didn't have to design just re purpose a lot of your work ,i know it works great all i have to do is not make a mistake ! .,i want to finish off the time base circuits once i check them i will hook them up to the deflection amplifiers ..the CRTS are still not connected i will leave that till close to last .
If i am lucky and the CRT's behave or really i have not made an error I can then work on the PMT side of it at the moment the goal is a raster on both crts before the next step .

I am also going to document the in and out of all the sockets on the 2 main boards as a few weeks to months not working on this i will forget what gos where for future me .

BTW Steve i never switch the power on for long on something just made till i can see its safe so the next time i leave the circuits on a bit long check for voltages heating noise ..no noise no heating your more than likely not going to get a bang ...i think we have all made mistakes in the past got to learn from them i try to .




I
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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: NBTV Television Analyst

Postby Harry Dalek » Thu Apr 16, 2020 9:52 pm

Well so far i have a working high low power supply and working time base not using the 4046 but a crystal 4060 oscillator for same result less drift for this purpose ,the frequency generation works and also the line and frame ramp generation beautiful circuits designed by Steve Anderson always work flawlessly ...of cause as long as you make no wiring mistakes :wink:
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I plan to use 2 multi position switches similar to what i did for the PMT camera for multi system line frame rates ,so once i have wired up the switches i then go then back to the case mount the 2 circuit boards and the rest gets wired up slowly there i can then test how the deflection amplifiers operate powered up fingers crossed ..if all good i move onto the first CRT ,once both CRT's can produce a raster i move on to the PMT side of it ...getting there !

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Last edited by Harry Dalek on Fri Apr 17, 2020 10:27 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: NBTV Television Analyst

Postby Steve Anderson » Fri Apr 17, 2020 4:07 pm

Thanks for the vote of confidence Harry - but I do make mistakes, more frequently than you might suppose...

Steve A.
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Re: NBTV Television Analyst

Postby Harry Dalek » Fri Apr 17, 2020 6:06 pm

Steve Anderson wrote:Thanks for the vote of confidence Harry - but I do make mistakes, more frequently than you might suppose...

Steve A.


Well this one works as you expected repeated a few times now so for me it was well worth the work drawing it up i can only think if not used in whole its similar to something you have made in the past for the ramp generator /

Hate making mistakes but you do learn from them :roll: .

Today I just hooked up the multi position switches to the line and frame circuits and tested a raster result on my old scope ..
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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: NBTV Television Analyst

Postby Steve Anderson » Fri Apr 17, 2020 7:31 pm

Harry, I might suggest a small modification to those circuits - it seems the vertical retrace is starting partway through a line - if I can find the original drawings!

Steve A.
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