Every-Day Tesla Coils

Triggered Spark Gap

Schematic drawing of my triggered spark gap.

The drawing above shows the lay out of my triggered spark gap. The case is made from a 6" length of 5" OD X 2 3/4" ID PVC bearing stock, capped on both ends with two 5" OD X 1/2" thick pieces of polycarbonate sheet. The end caps are each held on with six 2" long 3/8-16 nylon bolts. The main electrodes are 1 7/8" steel ball knobs with 3/8-16 tapped holes supported on 3/8-16 threaded rods of 18-8 stainless steel. The trigger electrode is a piece of 1/8" OD tungsten rod. All of the materials were purchased from McMaster-Carr.

In operation, the right hand electrode is grounded and the gap is set wide enough so that the high potential on the left electrode will not jump the gap. To fire the main gap, a high potential is applied to the trigger electrode, causing an arc to form. The plasma generated by the small arc increases the conductivity of the air between the main electrodes, allowing the main gap to break down.

Picture of my triggered spark gap, partially dissasembled.

This picture shows the finished triggered gap, with one end removed. The ground electrode can be seen through the end plate and the trigger electrode is sticking out of the top of the PVC case. The high potential electrode, mounted to the other end cap, is seen on the right of the picture.

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