(Information provided by Zack Ethridge (zacketh@ibm.net) in December 1995)

                 SOME VECTREX 3D GOGGLE QUESTIONS AND ANSWERS

The accompanying files 3dplacement.gif and 3dwheel.gif show details of
the positioning of the wheel in the goggles and a generic wheel. Actual
wheels have varying amounts of red, green, and blue areas that correspond
to the relative amounts of each of these colors in the associated game.

> In what direction the motor (and the wheel) should rotate?
> Clockwise or conterclockwise, in the user view?

As seen from the viewpoint of the wearer, the wheel turns counter-
clockwise.
 
> Also, on the goggles pictures there seem to be some
> mirrors inside of it.  What are their purpose?

There aren't any mirrors in the goggles.  There is a clear plexiglass
viewport for each eye, and the front of the goggles is clear plexiglass
also.  No mirrors.

> Is there a particular type of 5V motor that work best?
> Does it need to have a specific RPM.  Could a little walkman 3V motor
> work as well? 

I don't think it is very critical what kind of motor you use.  I think the
Vectrex will compensate for individual variances.  Probably.  I think...

 
> How does the color wheel attach to the motor ?  Do we have to use some
> kind of strap or is it directly fixed to the motor shaft ?  Does the
> wheel have a special kind of support ?

The color wheel has a rather wide thick-plastic center section.  This has a
square hollow-wall receptacle into which a matching square protrusion on
the motor axle fits.  On the other side of the color wheel is a round boss
which fits into a non-turning receptacle which acts as a pivot point,
allowing the color wheel to be turned by the motor.  See the 3DCOLORW.GIF
to illustrate this.  Probably.  I think... :]
 
> In an early article in the Vectrex newsgroup, someone talked about the
> plans of the goggles themselves that could be done on autocad (or drawn
> in any other way).  I don't really have problems with the electronic.
> But with the design, it's something else.  Do you know if there is a way
> to get plans of the body of the goggles and the layout of all the
> components ?  Particularly, I have difficulties with the photo transistor
> and the led.  Where do you place them ?  How far one from each other ? 
> The same problem with the motor (and the color wheel).

I don't know of any plans available for the goggles, nor a layout.  As for
the LED/phototransistor, see the GIF for placement.  In the goggles, they
are separated by about 3/4" (2 cm).  

> Do you know if it will be possible to efficiently reproduce the color
> wheels ?  I have a multicart that has all the 3d games but no wheel. 
> Could you give me a physical description of one ?  I have the diagrams
> available at the ftp site but no idea on the material which they are made
> of, neither the thickness or the weight (if these details are important).

The wheels are fairly simple: the transparent part is about 1/64" (.5 mm). 
The thicker opaque center section is about 3/32" (3 mm). 

I was told by a fellow that it should not be so hard to manufacture the
wheel yourself. Look at the drawings of the wheels in the archive at the
vectrex site. Then go to a photo shop and order "KODAK GELATIN FILTER"

Blue =#47    CAT 149-5787
Green=#58    CAT 149-5860
Red  =#25    CAT 149-5605

These are the right colors but very thin. Then buy some thin plexiglass and
glue them on the plexiglass.  

> Also, I wondered if I could use 1/4 watt resistors instead of 1/8 watt. 
> Do you think it may work as well ?

I think the wattage is not critical here; the 1/8 watt parts were probably
used for size and cost.  Probably.  I think...