Re: G08's and inductive kick

At 04:26 PM 8/29/97 -0700, you wrote:
>I'll bet removing those resistors and replacing the
>voltage with regulated voltages could possibly give a nice solid display
>without having to have, high power, low voltage, regulation.
>
>yup.. that's what they did in the ampliphone.
>
>We also just figured out what the two multipliers do in the WG vector
>generator design; they multiply the square of the opposite channel's
>deflection value, scaled down by a voltage divider to the channel's
>value prior to it being scaled by the pot/VDR linearity circuit.

I posted somewhere what those things were doing, if I wasn't so lazy I'd
have written a FAQ or something.

>From reading a lot of different sources I found that in some yoke/CRT shape
combinations (especially the older tubes/yokes) there is an affect where the
farther from the center of your CRT the beam is, the more affect the yoke
has on moving it. I never really was able to find out why, maybe something
to do with the inverse square law and the distance from the gun and the high
voltage grid attracting the electrons. The farther the distance the less
attractive force, leading to more "blooming". Whatever the reason, since
the diagonal corners are farther from the gun than the center of the screen,
as the beam moves from the top left corner down towards the lower left
corner it has reaches a point in the center of the screen where the beam
travels the least distance and the yoke has less affect, so the beam is not
deflected as far. Then as it continues its travel when it finally makes it
to the lower left hand corner it is now farthest away and the yoke has the
most affect on the beam you end up with the:

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affect. Since the affect of the X axis is dependent upon the position of
the Y axis the correction circuit for X is based on Y. I guess since the
top and bottom of the screen are closer to the guns there is less of this
sort of effect. I noticed on Tempest they have the pincussioning correction
for the X and Y axis and have disabled the Y axis correction by not
populating some resistors.

The linearity corrects the same problem. Blooming at the edges. Since the
beam has farther to travel towards the edges, the yoke has a greater affect
and things would get bigger towards the edges if not corrected for.

I don't know why B&W monitors and the newer Color tubes are less affected by
pincussioning, but are still affected by blooming, except that I've read it
has to do with the design of the tube/yoke combination. They've obviously
extended the distance between the guns and the front of the screen in
amplifone tubes, the would decrease the distance ratio between the edges of
the tube and center, maybe that helps. I've noticed all tubes in the newer
raster displays (there are no *new* X/Y monitors :^( ) have the bulbous
length of the amplifone tube, this must help them to deal with pincussioning.

-Zonn
Received on Fri Aug 29 17:18:24 1997