Cold cathode Long Phosphor persistence build experiment

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Cold cathode Long Phosphor persistence build experiment

Postby Harry Dalek » Sat Nov 14, 2015 10:57 pm

A little while back i scrapped a compressor and some other parts for vacuum High Voltage experiments for a bit of fun and try something thats been on my mind .

I made today what i hope will be long Phosphor persistence cold cathode CRT and see how it gos..... for a start i will try to get a unfocused spot .

What my dream is may be it is possible to make a DIY long persistence CRT from scratch ...for the original SSTV system . i was very happy being able to do it mechanically a few years back so if theres a will theres a way .

I noticed due to the small amount of air that is left in the near vacuum the electron glow is towards violet which is what i want ,as my screen Phosphor which is paint mixed with glow powder(orange but when i mixed it with some white hobby paint it glows green) will glow i hope even if the electrons don't do it .i'll find out soon either way .

Theres a lot of experiments using cold cathode ideas using bottles beakers and such showing its not all that hard direct an electron beam to a screen ,I started the idea off by using a jar with a lid as it helps not having to drill into glass and you can keep the holes down and you have a nice large work area and so on ...

The thickness of the jar glass worried me at first in case changed the size of the beam spot but tried it with a laser and its fine ...I tested the phosphor tonight and it glows fine mixed with the paint all thats really left is testing it with a high voltage and see ...at the moment on the power supply i only have something that gos up to 1000 volts so i might try it on that and see ...the glow powder i am using out does past long persistence paint so would not need much to get it glowing any case all i have at the moment to try this idea out .

BTW the copper tubing is soldered on and glued over just in case ,i put a valve on my vacuum pump so i hope i can shut it and keep vacuum for a bit ..

The last photo taken was a glow test with a uv led a few seconds after the paint was charged sort of what i hope to expect when the jar is in near vacuum and the HV is powered to it .IF any thing comes of this i will post up .
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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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Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 3926
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: Cold cathode Long Phosphor persistence build experiment

Postby Harry Dalek » Thu Nov 26, 2015 4:01 pm

Well mark one needs repair ! :oops:
It started off very impressive ,tube did light up which i suppose are cathode rays so i had a close vacuum ,it was a bit light this afternoon to see if i had a faint spot or any thing on the screen , had no voltage control so things were bound to go wrong .
Then yes it all went to pot !
I didn't take into account once i had enough voltage which i did today 6250 volts there would be sparking the next problem was i used a plastic tube or rod instead of glass so the sparking caused heat and plastic melted if i can stop sparking this would not have been a problem .
The good thing is once again i know what to do and what not to :lol:
I was thinking i could only have one good shot at this so took my camera little did i know i was almost right ,i can repair and try and improve and not repeat the faults .
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Almost ready to start
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6250 volts on tube at atmospheric pressure slight glow on cathode
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we have cathode rays
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OH no its a disaster !!!!!
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The end ; (
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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.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 3926
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia


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