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Author: Subject: CRT Phosphor
atomicproject
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[*] posted on 10-8-2008 at 09:45
CRT Phosphor

I am currently working on a homebuilt CRT project. The target screen uses phosphor from a used fluorescent tube. That being the case, the glow is white. Is it feasible to add a very small amount of copper sulfate to the phosphor to make it glow blue? If not what would be good?

Here is a quick youtube link. The CRT is made from a 250 ml vacuum filtration flask and a test tube for the electron gun. The noise in the background noise is from the vacuum pump.

http://www.youtube.com/watch?v=nMOjiZR7R6U

Mark
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[*] posted on 10-8-2008 at 16:58


The short answer is 'no'. If you read the wikipedia entry for fluorescent lights you will see why.
The best you could do would be to put a blue filter in front of the crt.
Well done, building a working crt!



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12AX7
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[*] posted on 10-8-2008 at 17:42


Do you know what pressure that was at? It looks as if you're generating electrons (or positive ions if you're running it backwards!) from a glow discharge.

Blue, huh? Trying for that Tektronix look? ;)

Tim



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[*] posted on 11-8-2008 at 03:33


Yea I always thought electrons in a CRT were generated by thermionic emission? So what gives the blue glow :o?
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watson.fawkes
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[*] posted on 17-8-2008 at 09:57


ZnS activated with Ag is the basis for most old blue phosphors. My reference is Handbook of Electron Tube and Vacuum Techniques, by Fred Rosebury. Potassium silicate is the binder. A small amount of barium acetate aids gelation. A full recipe is in the same volume.
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[*] posted on 17-8-2008 at 13:22


I was talking about the electron gun, not the phosphor screen?
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watson.fawkes
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[*] posted on 17-8-2008 at 14:47


Electrons are electrons. Variations in color come from the chemical composition of the phosphor.
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19-11-2023 at 12:34

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