How to make capacitors for Tesla coil (small SG)

The first few versions of my small spark gap Tesla coil used commercially made capacitors but I wanted to show how to make homemade ones instead. I first made some using soda bottles but they took up a lot of storage space, so I then made some flat plate capacitors instead. Both of these are detailed below, along with videos showing step-by-step how to make them.

Make flat plate capacitor for Tesla coil

This homemade flat plate capacitor is what looks like a small, horizontal board at the base of the Tesla coil below. It has 4nF of capacitance.

Tesla coil with flat plate capacitor.
Small spark gap Tesla coil with flat plate capacitor that
      appears as a horizontal board at the base of the Tesla coil.

For the dielectric I had some transparencies which you can get from photocopying stores, like the UPS Store, basically places that do photocopying and printing for you. Kitchen aluminum foil served as the plates. And looking around I found some thin wood that would act as nice solid pieces to hold everything tightly together as a sandwich. For bolting it together I had some 1/4" nylon nuts and bolts from Home Depot.

Transparencies from a photocopying store.
Transparencies bought from a photocopying store.
All of the parts for the capacitor.
All of the parts for the flat place Tesla coil capacitor.

My small spark gap Tesla coil was designed for a 4nF capacitor and it turned out that just two plates with a single transparency between them measured 3.86nF, which was close enough. I could do tuning on the primary circuit's spiral coil to make up for the difference.

In the first photo below only the top piece of wood is missing. The two aluminum foil plates have a single transparency between them. The positive plate is the bottom one and has the red wire connected to it, and the negative plate is the top on and has the black wire connected to it.

Capacitor without the top wood piece.
Tesla coil capacitor without the top wood piece.
Measuring the capacitance.
Measuring the capacitance of the Tesla coil capacitor.

Below is a video showing step-by-step the construction of this capacitor, along with some variations and demonstrations of it in use.

Make soda bottle capacitors for Tesla coil

I decided to try the large 2 litre/2 quart soda bottles since the large surface area would give a reasonable capacitance and the plastic has a high breakdown voltage. Also, once you cut away the top, they have a fairly open end for reaching your hand into for putting an aluminum foil electrode.

Tesla coil with soda bottle capacitors.
Small spark gap Tesla coil with capacitors made from soda bottles.

Each soda bottle capacitor ended up having a capacitance of between 1nF and 1.4nF, depending on how close the aluminum foil was to the plastic everywhere.

DIY/homemade capacitors for the Tesla coil.
Three DIY/homemade capacitors for the Tesla coil.
Capacitors in place beside the spark gap.
DIY/homemade Tesla coil capacitors in place beside the spark gap.

The following is a video showing step-by-step how I made these capacitors, along with demonstrations of them in action.

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