OT: need to drive a vector CRT...

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Mon Sep 15 20:26:00 2003

> I know this is off topic for the list, but you folks are my best choice
> for the kind of knowledge I'm after. :)
>
> The task at hand is driving a 4" diameter vector CRT. _Any_ 4" vector CRT

What the heck is a 'vector CRT'? AFAIK such things don't exist. whether a
CRT displays 'vectors' (meaning you deflect the electron beam to a point,
turn it on, then move it along a line to display that line), or a
'raster' (meaning you scan out a series of lines and modulate the beam to
display an image) depends on the external circuitry, not the CRT itself.

Magnetically-deflected CRTs (like those in most monitors and TVs) are
generally easier to use to display a raster, but
electrostatically-deflected CRTs ('scopes, 'vector displays', etc) can be
used for either.

> round CRT is needed for. It's my understanding that it's possible to
> drive a CRT like this "oscilloscope style". Where can I find out

Yes. It's alos possible to display a raster on it. In fact I've _seen_ a
good 'scope (with 2 timebases) be used to display a TV-rate image.

> information on how to do this? Is there any kind of black box that I can
> buy or build that will allow me to feed an NTSC or VGA signal in one end
> and get a correct vector signal out the other?

It's non-trivial to turn a raster image into an optimised vector image
(which would involve finding lines in the image, and then drawing them).
It's not as hard to make a framestore that outputs the 2 deflection
signals and intensity to drive a 'scope-like CRT in raster mode.

The problem with doing this is that you might not be able to get enough
intenstity out of the CRT to display a raster in a useable manner...

-tony
Received on Mon Sep 15 2003 - 20:26:00 BST