Mark Crowley wrote:
Hello all, My first post and my first question! I recently came into possession of (2) 15 KV non-gfi neon sign transformers @ 60 mA each. I plan to parallel these two together for 120 mA total to feed a large coil. Although not my first Tesla Coil, it is by far the largest I have undertaken. My question is what would be the optimal secondary size for this? I've searched the archives here and it looks like 6" to 10" diameter seems to be preferred but have also heard 4.5 Inch diameter coils driven as well. A height to diameter ratio of 4.5:1 seems to be recommended too. I already have two large spools of 27 AWG and 24 AWG high temp wire available so I would like to use those if possible. I have not purchased the sec form yet. (I also have a 24 inch diameter toroid available).
I am currently running 12kV at 120mA (a modified 12/60) on a 6.25 inch coilform. I used 1400 turns of 24AWG for a winding length of 30". The toroid is 7"x29", and the gap is an SRSG I made by modifying a 1/4HP motor.
It's running great now that I have the new toroid on it. Before I made the current toroid, I tried using my old 4.5"x23" with this setup, but I was getting multiple streamers, so I built the bigger one to put all of the energy into just one streamer, which is working out great.
If your transformers are the old kind (potted in tar), you might be able to depot them and remove some of the shunts to get more current out of them.
Jon
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