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Registered Member #3054
Joined: Sun Aug 01 2010, 05:25PM
Location:
Posts: 13
Hi all!
While playing around with my little SGTC, I've been able to make some observations that I, as an amateur, just don't understand. I'm hoping to get some clarification.
I've got two different scenarios to cover. My little coil is a SGTC running from a 15kV 30mA NST with spark output of +/- two feet. The top load is a toroid.
Scenario 1. (This one is very stupid and unsafe...I know. I don't need a lecture, since I don't do it any more.) I isolate myself from ground by perching myself in a plastic lawn chair. With a long metal rod in hand, I reach out and touch the sparks with the other end of the rod. From the side of the toroid, I don't feel a thing when the sparks touch the rod. When I move the end of the rod above the coil however, the hair on my arms and head begins to stand up, and when the sparks hit the rod, my muscles twitch, and I definitely feel the jolt. It's not painful, but notably different! The effect is even more pronounced if I hold a larger metal object such as a 4"x16" toroid made from dryer duct above the coil.
So, can anyone tell me what the real difference is? Why is it so different above the coil than beside it?
Scenario 2. (Much safer) I isolate a large toroid (7"x36") from ground in the same plastic lawn chair and bring it to within about 18" of the coil. I turn on the coil and immediately, white-hot sparks start licking the toroid with no breakout anywhere else from the coil. There's no object on top of the coil to initiate sparks either. Next, with the toroid still in the chair, I ground it by leaning a metal curtain rod against the side of the toroid away from the coil. The other end of the curtain rod is in physical contact with the earth. Switch on the coil. This time the sparks that touch the toroid appear very "wimpy" in that they're very thin and stay purple, and are surrounded by a thick "beam" of corona. Plus, there's notable spark output from the top of the coil itself with streamers tangent to the toroid as if they're trying to reach around it from the sides. To give it a hug, as it were.
So, what's going on here? I'd have thought the sparks would be eager to complete the circuit to a grounded object, that doesn't seem to be the case. Why are the sparks hotter when striking an ungrounded object?
I imagine I'm missing something forehead-slappingly simple
If pictures (of scenario 2) would help, let me know. I'll do my best...
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Some observations and questions regarding my little coil
