Tuesday, April 14, 2009

VDG assembly overview

Starting from the top down, original design. I'm redoing the top roller since it was having serious problems, which I'll describe later.

The top is made of two steel mixing bowls taped together with aluminium tape. It's connected with a wire to a screen wire patch (aluminium). The screen comb is attached to the top of the main PVC shaft, and is very close (but not touching!) to the neoprene belt.

The upper roller the belt goes over is a piece of PVC pipe wrapped in aluminium tape (to make it be conductive), and spins on a smaller piece of PVC pipe which goes through a couple holes in the top of the main PVC shaft.

The lower roller is plastic, and is directly connected to the motor's shaft.

The base is designed to be expandable, it is made of wood, screws, some metal supports, and can have parts replaced relatively easily, as well as cardboard inserted in some spots to more precisely set the belt's angle up (to make sure the top and bottom rollers are as close to perpendicular as possible).

The lower shaft (which doubles as the lower roller) extends out in both directions, through two bearings. Two small pieces copper pipe with 1/2" ID and very thin walls are on both outside walls of the base, superglued on (to stop the shaft from shifting while it's spinning). There is a drill bit glued inside one end of the PVC bottom roller, which a handheld electric drill can easily be attached to.

Friday, April 10, 2009

VDG works first try

First attempt the VDG worked, updates coming eventually for steps between this and last post.

Tuesday, March 31, 2009

Van de Graaff generator progress

Cut a couple strips of Neoprene to get the correct length & 2" wide strips, superglued together to make a belt.

Either a blender motor or hand held electric drill motor (both AC Induction (split-phase capacitor) motors) is probably best. Need to work out how to build a mount for whichever used. If possible, the base needs to be designed to switch the motor out.

The base has to be far enough from the top to hold the Neoprene belt as tight as possible, as long as the bottom doesn't break from the strain. It has to be stretched enough to be pulled from the inner edge of the PVC pipe and not have enough slack to attract itself and have the insides of the belt come in contact with eachother.

Tuesday, March 24, 2009

Updated Van de Graaff generator parts

Steel of aluminium mixing bowls
Aluminium tape
4x 5/8" outer diameter PVC pipe end caps (very specific since I already have that size of PVC pipe)
2x shafts or pins to mount PVC rollers on
Paint mixing bucket or other strong base that can have pieces cut out easily (and still be strong)
Superglue (superglue gel if there is a difference)
Gloves (to keep fingers safe while working with superglue)
Something to attach PVC to base, all screws going into the PVC column should be nylon
Electric motor at least 3000RPM
Neoprene belt 2" wide
PVC column 3-3.5" diameter, long enough to stretch neoprene belt slightly. Must be at least 3" inner diameter.
Metal nibblers (tool)

Monday, March 23, 2009

Van de Graaff generator possible parts

Going to work out in more detail later:

3"-3.5" inner diameter PVC pipe probably around 1.5'
mixing bowls, bigger the better
aluminium tape
4x end caps that fit small pvc piping
2x shafts to put pvc pipe rollers on (or similar)
paint mixing bucket
something to attach pvc column to paint mixing bucket
(if anything needs to go into the column, it has to be non-conductive)
electric motor at least 3000rpm which could drive the belt
power supply for motor (probably a stack of batteries)

neoprene belt, 2" wide, probably around 36" long

2x 1/2" pvc pipe

Van de Graaff generator parts overview


Circular base to bolt the support column to and a very smooth hemispherical aluminium shroud with a hole in the top for the support column. The shroud should have a small spot on the bottom edge cut out for any wires to leave.

Support column:

A single Acrylic tube, large enough for the belt


Two hemispherical aluminium shrouds connected together, with a hole in the bottom for the support column

Inside the base there will be a motor of at least 3000RPM, a plastic roller and a comb to catch electrons off of the belt. The comb should be 1/32 inch away from the surface of the belt. The pulley, motor mounting and comb should all be grounded.

The support column only has the belt in it, held taut from rollers below & above the support column.

The head will have a metal roller at the top of the pulley, not connected to the metal sphere. The sphere will have a comb going from the inside to 1/32 inch of the belt.

Sunday, March 22, 2009

Van de Graaff Generator start


Schematic view of a classical Van de Graaff generator.

1) hollow metal sphere
2) upper electrode
3) upper roller (metal)
4) side of the belt with positive charges
5) opposite side of the belt with negative charges
6) lower roller (for example in acrylic glass)
7) lower electrode (ground)
8) spherical device with negative charges, used to discharge the main sphere
9) spark produced by the difference of potentials

As the motor spins, the belt travels around the two pulleys. Electrons are collected from the top via the electrode and travel down with the belt. The electrons jump off the belt onto the electrode at the bottom, and the belt travels back up positive (ready for more electrons)