High Voltage Experiments

	The Leyden jar starts out with a standard jam jar.
	Pieces of adhesive aluminium foil are glued to the inside of the jar first. This way its easier to see which bits you have missed the strips should not come more than 3/4 of the way up the jar for the highest voltage capacity
	If you can’t get you hand in to the jar to stick the pieces down use the handle of a screwdriver  to smooth out the pieces. The foil does not need to be absolutely smooth, but there must be no gaps. Corona will form on any edge and eat away at the foil.
	Go right around the jam jar until the whole of the inside is covered. to the 3/4 height. Strips of 20-25mm work best. Larger strips become difficult to handle.
	For the bottom of the jar use 25mm square pieces. Stick them on to the end of your screwdriver to position them.
	You may need to use more than one screwdriver to get them to stick where you want.
	Cut a circle of Acrylic bigger then the lid of the jam jar, and cut a circle of copper or brass to fortify the bottom.
	As we are not using water to contact to the inside we need something to stop the foil wearing away a copper of brass circle will spread out the current.
	Stick this down with the foil. You may need to bevel the copper plate slightly as some jam jars have a domed bottom.
	Taking a single sheet of foil slightly longer than the height of the inside foil and wrap it around the jam jar. leaving some spare at the bottom.
	Smooth down the extra over the bottom.
	and add a patch to the bottom and smooth it down.
	Use your finder mail to burnish the outside foil of the jam jar.
	For the inside conductor I used a piece of 5mm copper brake pipe to make securing this easier to the top I used a piece of 2mm copper wire that I attached a ring tag.
	Using another piece of the 2mm copper wire I formed a crude spring around a 10mm drill bit.
	The finished inner contact.
	I glued a 25mm long x 50mm diameter piece of water pipe to the centre of the top circle of acrylic. This fits the inside of my jam jar snugly.
	The top and inner conductor are put into the jar, so that the spring contacts the bottom of the jar. The inner ring is glued into the inside mouth of the jar to stop the spring from pushing the top out.
	A small brass ball was tapped and attached to the bolt from the centre contact.
	The finished jar.
	Using a spare piece of the 5mm copper brake tube and  a couple of spare brass balls I made a discharge tool. The handle is made from a piece of nylon bar. Although these jars will not store enough charge to kill, they can pack nasty punch. Better to discharge the jar with an insulated tool.

 

 

 

 

 

How to create conductive balls for HV experiments

Start with some light balls,ping pong balls or polystyrene balls are ideal.

For coverings see below.

Method 1 (Aluminium foil)

Cover the ball in adhesive aluminium foil. Burnish to a good finish, If using polystyrene balls, be careful not to burnish too hard as the surface is easily deformed..

Method 2 (India Ink)

Coat the surface of the ball with India Ink. India ink is slightly conductive and will form a conductive outer shell. coat the ball by holding it between the fingers. When dry coat the bits that were covered by your fingers. Polystyrene balls may need a coating of an acrylic sealant to stop the ink from being absorbed into the polystyrene.

Be warned, many products that say they are India ink are actually an acrylic substitute and not conductive at all.

Method 3 (Graphite powder)

Evenly coat the surface of the ball with glue (be careful not to pick a glue that will react to the plastic surface, PVA works well  for both polystyrene and ping pong balls) To get an even finish I rolled the ball against a couple of pieces of acrylic. When the glue starts to become tacky, coat the ball in Graphite lubricant, keep rolling until the surface of the ball has an even coating. Allow to dry thoroughly before using.

After some use…
Be warned that arcs to the surface will quickly heat up the pingpong ball and a fire may result.

Method 4 (Aluminium Foil)

Screw up aluminium foil and roll until a small ball shape is formed. Fine for small suspended balls, but not round enough to roll and difficult to make with any large diameter.

 Method 5 (Bear Conductive – conductive Paint http://www.bareconductive.com/) The Best method so far.

Recently this paint has come on to the market. Its is a thick paint that comes in either a pen or a bottle. After a number of experiments I have found that the best way to coat a ping pong ball, this should apply to other balls too.

To coat a ping pong ball water down the paint to 50%/50% paint to water, this gives a much thinner and therefore more even coat. Run the ball through a bath of the paint until all of the surface is covered, Don’t worry too much about where your fingers have been as this doesn’t seem to make any difference to the end result. (another advantage of watering down the paint is with 100% paint your fingers leave lumps in the finish.)

Please note that this paint is recommended for voltages of up to 12V. So if you are applying higher voltages than this, you are on your own.
Be warned that arcs to the surface will quickly heat up the ping pong ball and a fire may result.

A rough guide to coating, conductivity and surface after paining ping-pong balls, conductivity is measured across the furthest points of the  sphere. Coating is given in water / paint percentages.

100% – too thick after one coat – long time to dry – uneven surface – 500 Ohms
50%/50% – Quick Dry good coverage – 1 coat – good surface – 6k
75%/25%  – Bad coverage – needs multiple coats – long drying time – good surface – missing coverage where handled – 10 k – 20k (variance  due to uneven coverage)

See also

>> http://smackaay.com/2009/01/13/making-a-conductive-adhesive/
>> http://www.instructables.com/id/Conductive-Glue-And-Conductive-Thread-Make-an-LED/step1/Make-Conductive-Glue-Conductive-Paint-and-Conduc/
>> http://www.talkbass.com/forum/f38/diy-conductive-paint-cavity-shielding-589012/
>> http://www.ehow.com/how_5031497_make-conductive-ink.html

Equipment

 Jam jar
Acrylic Disk or plastic lid for Jam jar
Thin Aluminium foil
50mm Bolt & nuts

 

Diagram

 

Method

Drill a hole in the centre of the plastic lid for the bolt to go through. Saw a slot in the screw end of the bolt. Place the bolt through the plastic lid and bolt in place leaving 20mm of bolt and the bold head sticking out. Glue two thin sheets of aluminium foil 30mm long and 10mm wide from a chocolate wrapper into the slot ensuring that the foil is not glued together. Replace the lid on the jar and secure.

 

Equipment

Jam jar
Plastic Lid or acrylic circle
50mm Bolt and nuts
Water
Adhesive Aluminium foil

 

Diagram

 

Method

Coat the outside of the jamjar with the adhesive foil leave the top 25mm of the jam jar uncovered. Drill a hole for the bolt in to the middle of the jam jar lid, Secure the bolt with the head and 20mm of bout sticking out of the top of the jar. Fill the jar with water and secure the lid ensuring that the bolt contacts the water.