Sciencemadness Discussion Board

rectifying HV using a monitor-tube

chief - 12-2-2009 at 10:44

Just as a idea: Theoretically one might abuse some monitor-tube to rectify quite high voltages ... ; it has a kathode and an anode, and probably a quite high breakdown-voltage ...

The heating-voltage of the cathode might have to be supplied by a low-voltage-transformer, using a very well insulated secondary ...

As for the x-rays: How is it : The lead-glass might or might not filter the higher energetic ones (50 + kV) ?

I wouldn't recommend doing this, but when the tube is beeing dug into ground somewhere, so that no x-radiation can come out ??

If the x-rays come out: Do these come directly through th front-screen ? Then the beam could be rastered, as usually, and thereby the origin of the x-radiation could be shifted around ... .


Also another abuse might be interesting: Signal amplification for high-voltage-signals ... ?

Mr. Wizard - 13-2-2009 at 10:23

Why not just use the high voltage that originally hooked to the anode of the CRT ? You can stack high voltage diodes in a voltage multiplying configuration to boost what would already be a high voltage output, at the limits of normal insulation. If you need higher voltages, I might suggest making a Vandegraaf generator > http://en.wikipedia.org/wiki/Van_de_Graaff_generator <or a wimshurst machine > http://en.wikipedia.org/wiki/Wimhurst_machine <

Maybe I don't understand why you are using the crt 'picture tube' as a diode, when there are other better alternatives. Many older style TVs had a HV tube diode that was used with a 'flyback' tesla type coil to rectify the HV to the crt.

The mechanical static voltage generators are more practical than burying a crt, imo.

Sedit - 13-2-2009 at 22:02

Chief Iv have alot of experiance in high voltage, could you be a little more discriptive on what you are attempting to accomplish with the CRT? I feel I can help (and sort of understand)but i dont want to give information based on my assumptions because in this case that sort of logic could lead to death if I misunderstood.

[edit]
Side note and later into the six pack :D
but as far as the fear of the X-rays they only form when the high enery particals (30-50kv or higher)hit a vary solid substance such as tungston. Collision with glass should be of no concern but as I said My thoughts are as good as nothing at the moment :) PM me tommorow and ill help ya out iv been down this road many many times and I m glad to see that the fear has gotten you to slow progress if that makes sence,

[Edited on 14-2-2009 by Sedit]

chief - 14-2-2009 at 03:40

It was just an Idea, as it came to my mind, that such a crt-tube should have a _high_ breakdown voltage.
Lots of things could be abused with such a tube, not just only rectification; a few examples:
==> the electron-optics might be used to achieve some sort of triode-behaviour ...
==> the beam might be defocussed, and e-charge could be sent to some regions of the tube, thereby building up charges there
--> those charges could be abused, for some sort of high-static-voltage-generator with controllable 2D-output regions
--> maybe the metallic mesh would hinder this, but maybe too this could be somehow circumvented, by burning it with a strong beam eg.

==> also: As long as one is protected from the implosion-dangers of such a tube, it has a high surface, therefore high powers could be possible
==> compared to the HV-valves of old TVs such a tube is probably better x-ray-shielded
==> should x-rays be capable of emerging, then it would be a 2d-raster-x-ray-source

I'm not sure about this one: Implosion-protection given (distant room with no windows, alternative mechanism for destroying the thin tail of the tube in case of experiment-failure):
Maybe an intense e-beam could be directed onto a spot, melting the tube open there ... for whatever use ...

Maybe it all are no-good ideas, but it seems at least, that all those CRT-tubes might have some sort of use ; .

[Edited on 14-2-2009 by chief]