Tesla coil II

Higher Voltages

Wanting bigger and brighter arcs, I took a bit more time building this coil and used a better set of capacitors. These were kindly donated by Steve of http://www.scopeboy.com/tesla/ where they can be seen in a previous life with other even more impressive coils.  I used the same oil ignition  transformer used before for the initial HV supply. The top load capacitor below is, for the moment,  part of a cafetiere. 

The primary coil is made from copper brake pipe tubing.  The output voltage exceeds 390kV easily but can suffer from flashovers to the primary. I suspect, as these circuits are not connected together, there is enough conductivity in the chipboard base to allow a path. The plastic collar at the base of the secondary coil is an attempt to reduce flashovers.

In the picture below, an earth return rod reduces the stress on the lower windings of the secondary coil and prevents coil flashover. 

The primary circuit can be seen below. The spark gap is crudely made using three bolts.  However, adjusting the hex head of the centre bolt neatly alters the spark gap size. The array of plastic film capacitors can be seen on the left. Each capacitor is 47nF 1.5kV.