Tesla Coil 2 (Twin System)


The goal of this project was to create a "twin system" which consists of two coils that are 180 degrees out of phase. The difference in phasing allow the sparks from each coil to connect in the center.


Transformer 3 Neon Sign Transformers in parallel providing 12KV at 90ma
Capacitor MMC rated .02uf at 30KV
Seconday Two identical Secondary coils 24'' of 28AWG
Spark Gap Synchronous Rotary Spark Gap at 120BPS
Primary Coils Brass Weatherstrip
Toroid 4'' Aluminum Ducting



Primary Coils





Transformer Bank


Synchronous Rotary Spark Gap


The Primary Coils were made from Brass Weatherstrip. A very compact primary can be made with this technique. However, brass has more than resistance than the commonly used copper tubing. It did get a bit hot during operation.
The capacitor bank was built to be extremely reliable, as I had a failure of an MMC bank on a previous coil. It consists of three 15 capacitor strings in parallel, for a total of 45 capacitors. Threaded brass rod is used to connect the strings together.
Three Neon Sign Transfomrer were used for the coils power supply. Each transformer is rated at 12VK & 30ma. Three in parallel makes for 12KV at 90ma.
The electrode of the spark gap is a tungsten rod. Tungsten has the highest melting point of all elements, so it performs as an extremely reliable spark gap. The rotor spins at 1800 rpm, providing 120 BPS.

Final Results

After much tuning, the system eventually worked well. Originally I started with the two primary coils in series. I eventually went with the primaries in parallel. This gave a much better impedance match to the secondaries, and resulted in 48'' sparks between the two coils. The twin system was demonstrated at the 09 WWT in Black Canyon City, AZ.

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