Electrostatic deflection (scope-type) CRT set-up

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After my video on the electron mass, I thought its worth looking at setting up and electrostatic deflection tube basics to produce a dot on the screen. Although the acceleration voltages in these tubes are lower the electron gun assemblies can be a little more complicated than in an old TV CRT.
CONTENT:
00:00 - Intro
00:24 - driving CRT
00:56 - electron gun assembly
02:20 - Problems with stray charge
03:08 - Demo on educational CRT
04:16 - Large tube with X & Y static adjustment

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Опубликовано:

27 июл 2023

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Комментарии : 20

@peterjameson321 Год назад

Thank you Kram. Well presented and most informative as always.

@rustymotor Год назад

That is a magnificent Maltese Cross demo tube! How did you find that one?

@tuopeeks Год назад

This is one of a set of educational CRTs made by a Teltron. They are a bit expensive but come up on eBay and the likes as schools don't like using them so much these days.

@Atingmaykeko Год назад

cool video! Have you try turn the CRT into a SEM?

@tuopeeks Год назад

Thanks, in theory there are a couple of problems with regards to the geometry and the fact the CRT bulb is sealed. Interestingly, there is an old technique for imaging the cathode surface to examine the emissive condition, in a magnified image. Although its project and not scanned.

@Gizmos_and_stuff 20 часов назад

if you ground out the electrostatic plates, would they still act weirdly? Sorry if this is dumb, I don't really have any experience with these but hope to learn.

@T2D.SteveArcs Год назад

Cool mate

@T2D.SteveArcs Год назад

I think the one I posted on fb had an off centre gun, did you notice that the image was off to one side of the phosphor? I'm going to do another video on it and the mercury arc rectifier for yt.. do you think I can correct it with magnets? I think it took a knock in shipping... I wonder if you put a negative voltage on the cross you can achieve total cut off🤔 I like the right hand rule in action at the end of the video😅 I assume you put a coil round the neck?..

@tuopeeks Год назад

Not unusual to correct beam landing with magnets, should work. Yes, there is a coil around the front of the Maltese-X CRT, similar to the arrangement on my pervious CRT video to twist and shrink the image. I reckon I could make the cross -ve enough to scatter the electrons off the fluorescent coating

@T2D.SteveArcs Год назад

@@tuopeeks 😁

@videolabguy Год назад

I am envious of your Maltese cross tube. Question: Do you know of a modern source for the button style connectors you have connected to the post accelerator of you last tube?

@tuopeeks Год назад

The Maltese cross tube used to be common in schools in the UK. They were made by 'Teltron' and I think are still made but expensive. Unfortunately I don't know of a source for the button style connector on the cone. I was lucky enough to have kept in when salvaging the tube. I should have kept the socket too though.

@gregreynolds5686 Год назад

What would happen if the Maltese cross was connected to earth?

@tuopeeks Год назад

Earth is also common to the cathode end of the PSU so actually makes it worse. If the PSU was floating, I think it would only make a momentary difference then look the same as no connection.

@VoorTrekker88 Год назад

thank you! this is really useful to me! I have a pretty big collection of old crt tubes, some with really rare phosphor colors/types. I'm hoping I can get a setup like this together to start testing and perhaps photographing each of them.

@cambridgemart2075 Год назад

I also collect rare CRTs, my most treasured is an orange phosphor rectangular faced CRT from an old aircraft weather radar.

@Gizmos_and_stuff 20 часов назад

thats awesome

@Gizmos_and_stuff 20 часов назад

@@cambridgemart2075 orange? thats sick

@cambridgemart2075 19 часов назад

@@Gizmos_and_stuff I need to get it running; there is basically no data available, but I have most of the original hardware that was used with it, so stand a chance of getting some life out of it.

@rustymotor Год назад

That is a magnificent Maltese Cross demo tube! How did you find that one?