Re: SW Death Star Blooming

On Wed, Mar 29, 2006 at 07:09:30AM -0500, Christopher X. Candreva wrote:
> On Wed, 29 Mar 2006, simon wrote:
>
> > I noted the other day that as on most vector monitors during the death
> > star explosion some blooming is noticeable. I have heard that this was
> > intentional, I find this hard to believe. I just rigged up my HV probe on
> > my SW so that I could read the EHT during game play. it was rock steady at
> > 19.5KV until the explosion...it dropped by 4kv!! I thought as much. This
> > must be due to the amount of white screen. Can someone else check their
>
> Actually as I recall, this was on purpose. In the death start explosion the
> HV is lowered to defocus the display, to add to the explosion effect.
>
> Now this could be a case of saying "It's not a bug, it's a feature !".

For those who weren't around, or forgot, here are Jed's comments on the topic:

In order to have the Death Star explode the way we wanted it to, it wasn't enough to draw lots of concentric circles. We wanted to defocus the beam to fill it in. We briefly considered adding a vacuum tube to the monitor to control the Focus Voltage. Fortunately, the lead time for the part was too long. So what I did was to give the Vector Generator the ability to overdrive the monitor's color inputs. Overdriving the inputs causes the CRT to draw more current than it normally uses and drags down the High Voltage., which changes the normal ratio of Focus Grid voltage to Anode voltage, which defocuses the beam. This relationship is explained in The Secret Life of XY Monitors.

The entire text is here: http://www.jmargolin.com/vgens/vgens.htm#Star

-Mark

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Received on Wed Mar 29 07:52:36 2006