Improved Construction of Scot's Spark Gap

by Jochen Kronjäger

General description

The following design idea (see images below) for a static spark gap for use with tesla coils is based on a an idea by Scot, which in turn was based on the Richard Quick copper tube spark gap. Scot proposed precision machined grooves and holes to align and fix the copper tubes. The present design eliminates the need for precision machining and drilling by substituting the grooves with aluminum U-profile pieces.

The improvement of Scot's design with respect to a Richard Quick style gap or a row of parallel copper tubes mounted on a single base plate was that the total gap width can be easily adjusted through the distance of the two base plates, without affecting the alignment of the single tubes. With a spiral spring over the bolts between the plates (not shown here), adjusting can be even more reduced to just turning four nuts a few times.

Aligning the U-profiles

• Place pieces of U-profile side by side on one base plate, with every other piece upside down (see figure).
• Glue every other piece to the base plate with epoxy glue (high temperature resitant).
• Glue the remaining pieces to the other base plate, without removing them from beteen the already fixed ones.
• After the epoxy has hardened, seperate the two base plates together with their adhering U-profiles from each other.

Assembling the spark gap

• Drill one hole into each copper tube and through each U-profile and the base plate.
• Fix a copper tube to each U-profile with a single srew (see figure). All tubes are automatically aligned through the U-profiles, independent of the precise position of the holes and screws.
• Fix the two base plates at a suitable distance using four bolts and 16 nuts and washers.
• Connect some kind of lead to the two outer copper tubes. That's it.