Hi Phillip,I may not even have the term correct. But I look at "field control" (old term) as the control of how the spark is formed, where it's going, etc. Maybe spark control is a better term.
Normally, the spark is single channel and moves along the toroid. It does stop and breakout elsewhere in a couple seconds, but the spark usually moves outward and down. When it moves "down", I like it to stay off the primary. This is easy to do with a smaller coil in a garage where the air is still and becomes very ionized. When outdoors however and especially in windy conditions like we had, it's difficult to control the spark channel. In the case of the July 4th runs, I eventually had to crank up power to get the sparks out and away from the primary. Most hits then went to the garage door about 8 feet away, some went down and hit the ground, and some went back and hit the primary (but far less often than the run in the video). The run in the video I was trying to play with voltage versus current keeping the power about the same, and to no good result.
I smoked the brushes in the same ballast variac 2 years ago on a 4th of July night, so that is why I was trying to do what I could at a moderate power level (I didn't want to smoke the variac again). But after that run, I decided to go for it. It did much better, but I didn't run it as long. Another problem was bps. When you saw those multiple streamers, that's when I turned the bps down low (adjusting voltage and current), and then I would increase bps to see if my voltage and current swapping would help (it didn't). Normally, the coil likes about 350 to 360 bps, but I installed a new VFD the day before and didn't have it set to go past 80Hz (another hurry incident). I also use a PLC to control the main contactor, deadman switch, enable circuit, etc. Well, I lost the program in a computer that died earlier this year, so I had to rewrite the program (that was another task I had to do the day before). There were a lot of "little" things like that which got in my way, so needless to say, I started scrambling just to get the coil to function at all. And that's pretty much when it got dark, so I just left it as is. It happens from time to time. Luckily, no major damage. Although, I did burn off 2 primary ty-wraps which was an odd thing (I think this occurred from both a top load spark hit and auto-transformer action as it occurred about 10 inches past the tap point into the unused turns of which there were 3).
Take care, Bart Phillip Slawinski wrote:
On Mon, Jul 7, 2008 at 7:22 PM, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:Hi Phillip, Mainly, the field control was not good and the primary was under attack! That's mainly what I wanted to show.When you say field control what exactly are you referring to?Yea, hard to see most of it as the guy taking the video was all over the place. Had I known he had a video camera, I would have had him use my tripod. But nonetheless, it's one thing to get a few strikes to the primary, and quite another for the primary be the main focus. Hit's like that and that often can do damage. So I was trying to show what "not" to allow if you can avoid it. BTW, that secondary is a 1760 turn coil. Take care, Bart Phillip Slawinski wrote:It's hard to see what's wrong with the coil in this video. I'd consider that a good run if my coil was running like that ;). Of course it's hard to see anything at all in that video. It would have been nice if the camera had been fixed, and there was less zooming._______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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