مطلوب ترجمة DIY Lightning Wand a Handheld Van de Graaff

introDIY Lightning Wand a Handheld Van de Graaff Generator

Most instructions for building a Van de Graaff generator (VDG) are for
tabletop models; however
VDGs grounded through a person work well enough
to make a handheld version possible. The Fun Fly Stick, a popular toy,
is an example of a handheld VDG. This instructable will show you how to
make your own handheld VDG capable of producing sparks up to an inch
long with a few common items.

WARNING: Keep the VDG away from all electronics, including pacemakers,
hearing aids, and the cell phone you forgot was in your pocket. A VDG is
an ESD monster!






I

step 1Materials and Tools

Materials

[1] 3/4" PVC
[1] 3/4" PVC Tee
[1] 3/4" PVC Cap
[3] 3 1/2" x 1/4" Rubber bands (No. 64)
[1] Super Glue
[1] Hot Glue
[1] 3 ft 16 AWG Stranded Wire (can be taken from old extension cord)
[1] Motor (like Radio Shack #273-223)
[1] 4xAA Battery Holder (like Radio Shack #270-391)
[1] Wooden Dowel
[1] Aluminum Foil
[1] Aluminum Can
[1] Wide-mouth Plastic Bottle like a 32 oz Gatorade bottle
[1] Paper clip
[1] polyvinyl chloride electrical tape (Scotch 3M 33+ or 35)
[1] Teflon tape
[1] glass bead
[url//www.artbeads.com/czech-glass-rondelle-9mm.html]

Tools

Pocket Knife
Can Opener
Wire stripper
Saw
Drill or Lighter, Nail, and Screw
Hot Glue Gun
Alligator Lead or Stiff Wire hooked at the end
Paper clip

Before starting, wash your hands and prepare a clean work area. The
three enemies of a VDG are oil, water, and dirt. Therefore you should
clean and thoroughly dry every part before construction. Use nonsoapy
water only since soap can leave a conductive film. Before touching the
rollers or belt wipe your hands to remove any excess oil.

step 2Motor and Bottom Roller

The motor doesn't quite fit in the PVC Tee. Cut about 18 in of
electrical tape; then cut this strip lengthwise. Now wrap the strips
around the end of the motor closest to the terminals. Add or remove bits
of tape until the motor fits.

To create the bottom roller, cut a narrow strip of polyvinyl chloride
electrical tape and wrap it around the motor's shaft. The best way to
get the tape to wrap around the shaft is by pinching the tape to the
shaft and rolling it between your thumb and index finger. You also want
to crown the roller (make it thicker in the middle) by pulling your
index finger slightly to the right for a couple turns then pushing back
to the left for a couple more turns repeatedly as you roll on the tape.
A crowned roller will keep the rubber band from slipping off the roller.
Add a bit of super glue to the end of the tape strip to prevent it from
unrolling, also add a little super glue to the edge of the roller to
bind all the layers of tape together. I tried making rollers out of
Teflon tape and silicone rubber, both of which are lower on the
triboelectric series, but a roller made from electrical tape was easiest
to work with. I did not know what material the generic black electrical
tape I had was made from, so to be positive the bottom roller was
vinyl electrical tape I used blue 3M 35, but 33+ should work well too.

step 3Bottom Comb and Battery Holder

Now you need to drill a hole in the Tee for the bottom comb. You can
also make a hole with a heated nail, and use a screw to widen it. Do
this in a well ventilated area. See the pictures below, for proper
placement of the hole. Next, cut a length of wire about 8 in long and
strip 0.25 in of insulation from each end. Insert the wire into the hole
and tape it to the Tee like the picture shows. Not taping the wire at
the hole will allow you to adjust the distance of the comb from the
roller so that you can find the optimum distance once you have the
generator built and running.

The Radio Shack motor is meant to run at 1.5-3V, but if you use
rechargeable batteries you can run the motor at 3.6V without too much
trouble. A higher motor voltage causes the motor to turn at a higher RPM
which results in more HV at the collector. I didn't have a 3xAA battery
holder so I made a dummy battery out of a piece of wooden dowel cut to
the same length as a AA, wrapped that in aluminum foil and insulated the
sides with electrical tape. Hot glue the battery holder to the side of
the Tee.

The Radio Shack motor has very thin brushes and lacks in construction
quality. It gets the job done, but I'm positive there is a better
motor out there waiting to take its place. Suggestions for a new motor a
more than welcome.

step 4Belt

A longer belt causes a larger charge separation which means a higher
voltage will result at the collector. Turning three rubber bands into
one long rubber band is easy with a pair of scissors and super glue.
Brand new rubber bands are a bit stiff, so stretch them out to loosen
them up. Now cut each rubber band. Try to make a very straight cut, so
that when you glue the ends together they will make good contact. Place
a drop of super glue on a piece of paper and spread it around with a
toothpick. Now dip the end of one rubber band in the glue and adjoin it
to the end of another rubber band. Don't overlap the edges; you want to
directly affix one cut end to the other. Also don't use too much glue;
you don't want a glue bond, you want the glue to heat the edges of the
rubber bands so that they fuse together. Hold the edges together
for around 10 seconds and don't stretch it for 30 seconds. A proper bond
can be stretched quite far, much further than required for the VDG.
Repeat, until you've made one large rubber band, minding not to twist
it.


Tips

Too little glue is better than too much. Even if the bond doesn't occur
along the entire edge, you can still see what the proper bond should
look like before trying again.
Don't be afraid to mess up. The bound sets quickly, so you know right
away whether the result is any good, and if it's not just trim the ends
and try again.
You should use brand new rubber bands; old dirty rubber bands aren't
worth the trouble.

step 8FUN

Turn off the lights. Observe corona discharge by pointing a finger at
the collector; the tip of your finger should have a blue glow. Hold the
back of your hand near the bottle lid to cause brush discharge. This
will look like lots of little lightning bolts. Draw a spark from the
collector by moving one of your second knuckles towards the collector.
If you've got your VDG working well you should be able to draw sparks a
little over an inch long. Since dielectric breakdown of air is
approximately 84kV/in (33kV/cm) this tells us the collector voltage is
around 84 kV! Tape a needle to the the top of the collector and hold
you're hand over the tip of the needle. You should feel a cool breeze.
This is called ionic wind.









Ring Franklin's bells. I like to set up Franklin's bells without a
grounding wire; normally the can on the right in the video below would
be grounded. Without the grounding wire the tab/clapper transfers charge
between the cans until both cans are at the same voltage as the VDG.
Then one can turn off the VDG, set it aside, and then discharge the
second can; lo and behold, the bells start ringing again as if by magic.









Cause an incandescent light bulb to flash a violet-blue. A burnt out
bulb works fine. Cover the glass with some clear tape to prevent
shattering if the glass breaks.









Bend a thin stream of water.

Deflect soap bubbles.

Light a small neon bulb.

Stick paper to a wall.

Levitate Fun Fly Stick fliers.

Check out Prof. Bunsen's Fun Fly Stick video for various demostrations
of a handheld VDG's powers.









Bill Beaty's website
describes some other interesting VDG stunts.



[b] _NOT FUN
_
Giving a shock to someone who isn't expecting it sounds like good fun,
but it's a bad idea. Though the current and pain will be minimal, the
surprise of the shock could cause a person to jump back reflexively and
hurt themselves. It's also possible you could destroy an expensive or
essential electronic device they have on them.

You can make a CFL bulb glow, but you probably shouldn't. Once I was
making a CFL glow while holding it in my hand when I received a shock
much brighter, louder, and more painful than anything I've received from
the VDG by itself. Unlike an ordinary fluorescent tube a CFL has an
integrated starter and ballast. This circuitry contains capacitors which
will charge slowly from the VDG, but will release that charge all at
once with the result being a higher current and a bigger shock. If the
shock doesn't harm you, the surprise of it could cause you to drop the
bulb releasing mercury and broken glass into your surroundings.

Never charge a capacitor with a VDG unless you understand the risks
involved. A VDG is a high voltage but very low current device. A
capacitor can have high voltage and supply a potentially deadly current.

[/b]