Re: New to the group

>Thanks for the input. The coil plans I have are for a solid state DC powered
>coil w/ a 25V .5A power supply. (wimpy coil) What are the advantages of
>using tube coil in comparison to a solid state? I would prefer to build
>which ever one is the most forgiving. 

Then you should forget both designs and chose the type that tesla built.
For a small powered coil this is not as hard as it sounds.   All the parts
can be home made (except the noen transformer).

To get you going I will describe a really simple system.

Spark Gap:
   Two bolts mounted on insulating material so that there is air gap
   of about 1/8"

Tesla Primary:
   Wind a spiral of copper pipe about 12-15 turns starting with an inside 
   diameter of about two inches more than the diameter of the secondary. 
   Outside diameter roughly the same height of the secondary.

Tesla Secondary:
   Wind 900-1000 turns of wire around a 4"-7" plastic tube single layer.
   Choose wire size so that the coil length is not shorter than 3 times the
   diameter, but not more than 4 times the diameter.   PVC pipe is OK but 
   needs sealing with polyprop varnish before winding.   Varnish your coil 

   4 Sheets poly (total thickness 40/1000") 2.5meters long 0.5m wide,
   then 1 sheet of foil 2.4 meters long and 0.5m wide, but allow 1 edge (length)
   to overlap the poly to allow 5cm border.   4 more sheets of poly, then another
   sheet of foil - allow overlap but down the other side.   Roll it all up around
   a length of plastic pipe.   The foil extending from the ends of the roll are
   the terminals of your capacitor.  The value will be around 0.02uF at lots of Kv.

   This capacitor is OK for TC work but dont run for too long (5secs) as hot spots
   will occur in the capacitor which will melt the poly sheet.  This is due to 
   carona discharge, so vacuum impregnating with mineral oil is recomended.

   For connections to the cap wrap wire (very tight) around the foil ends clamping
   against the plastic pipe.

   Secondary discharge terminal should be toroid in shape and large 24" diameter.

Take a look at:


>There is a lot of discussion on "
>rotary gaps ". What are these exactly? They sound like the distributer cap
>and rotor in a car. Is this correct ?, and where could I get alternate coil
>plans on the net? I have driven the local book stores nuts trying to find
>info. on TC's. 

Rotary gaps are for later when you get your coil going and you want to make
it work better.   The simple static with two bolts will get you going.  I get
22" streamers from my coil using such a gap.   

Your right a rotary gap is simmilar to a distributer, only its function is 
to act as a fast high voltage switch.   Electrodes are mounted on a rotating
disk.   These electrodes brush past two static electrodes thus completing a
curcuit.  As the disk continues to rotate the moving electrode breaks the
connection.   Pulse rates of around 500Hz are typical.   A static gap only 
fires twice per mains cycle, 100 times for 50Hz (UK) 120 times for 60Hz (US)

>Nathan Howard

Hope this helps

Julian Green