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Re: 43" in first run
Finn:
Nice job on the first run of your new coil, wait until the neighbors start
coming out to see what is going on! I would expect with your power level
and capacitance in the primary circuit, you will exceed a 2 m spark length
very soon. Keep working on the primary tune and coupling and you will soon
get to that point and beyond. I would suggest now working with the primary
tap point to achieve maximum spark length. As you are hunting for optimum
tune, you may also want to get some plastic sheet from the local paint or
hardware store. I have used this thin plastic to wrap the lower section of
the secondary during the initial tuning process, three or four turns minimum
over the lower 50% of the secondary. It simply helps protect that fragile
secondary winding from primary/secondary flashovers. I damaged one big
secondary two years ago with a healthy arc during the tuning process, so I
have tried to be careful ever since. Good luck with your efforts and nice
job.
Chuck Curran
----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, April 30, 1999 9:41 PM
Subject: 43" in first run
> Original Poster: Finn Hammer <f-hammer-at-post5.tele.dk>
>
> Today I fired my coil for the first time, and this was also my debut as
> a coiler. Since I have changed my mind all the time, during
> construction, I will start to describe my system.
> 400 volts trough a homemade variable choke that can "seduce" the 3kW
> 20kV homemade pig into delivering from 10 to 400 mA into a short or
> jacob ladder.
> Sparkgap is a series sparkgap with 28 gaps 0.4 mm each, for a maximum
> total of 11,4 mm (1/2") This length can be altered, but this was what I
> used this time.Sparkgap is sucked fy a vacum cleaner run by a variac.
>
> Cap is a MMC with 600 philips 376, 0,022 µF/1600 V caps in 30 strings of
> 20 caps, each paralled with Philips VR37 33mOhm resistors. 34nF total.
>
> primary is 14 tyrns of 8mm copper plumbing tube, spaced 8mm (8mm=4/16")
>
> Rf ground is 3 lengths of 2mm copperplate, 1 m long (3feet)and 10 cm
> wide(4"), hammered into the ground in a triangle, 2 meters apart(7´),
> and connected with 50 mm wide plate, 2 mm thick. all soldered together,
> and in one corner, there is one strap more soldered on, which connects
> to the strike ring, and the base of the :
>
> Secondary, 250 mm dia.(10") 820 mm long(32") with about 800 turns of
> 0.95 mm wire(AWG 18.4)
>
> Anticorona ring is 85 mm dia (3,abit") by 350 mm center to center(about
> a foot). Main discharge terminal is a 320mm by 640 mm toroid (12" by
> 24").
> I had measured the res. freq. of the secondary system to 105 kHz, and
> found a point on the primary btwn, 11 and 12 turn. that resulted in
> 100kHz, thinking that I would make up for the rest with streamers.
>
> Furthermore, I measured the coupling to be 0,17 with the secondary in
> level with the primary, 0,15 raised one inch, and 0,13 raised 2 inches.
> I started the coil with K=0,17.
> It was a beatifull, almost windstill evening, and I set the sparkgap at
> 4mm(0.16") for thefirst run, no breakout, but the neon tube did light
> up, so I threw a length of shield from a antenna caple on the toroid,
> and bent it out about 5 cm (2") to form a discharge point. This created
> a spark to the grounded rod 36 Cm (14").
> I opened the gap to 6.6 mm (0.26") and the discharge grew to 60 cm (24")
> Tapping in 1/32turn brought the discharge up to 85 cm (34")
> Then I opened the gap up to 7.2 mm (0.28") and got 110 cm (43").
> By then the safety gap, which I had set to fire at 20 kV started to kick
> in very regularly, and I got one interturn flashover on the primary,
> which I interpreted as the result of too high coupling, but what do you
> think? Perhaps a little dew was falling, anyway, I was at a point where
> I felt it was time to let the experience sink in. So I packed up, and
> called it a day.
> No doubt, there is more to be had, when I get the hang of tuning the
> coil properly.
> Sparks to the ground rod were white, streamers were definately violet,
> and my son said he thought his dad is cool! :-)
> After the session, the cap measured 34,3 nF, whereever the last 0,3 came
> from is a mystery to me.
> I would like to extend my thanks to the members of the list: You guys
> sure know how to bring up coilers. Special thanks to Bert Hickman for
> patient tuition on current limiting, Terry Fritz for having the manycap
> pictures on his site, and the german gang for talking the whole thing
> about MMC up.
> Maby it is true that a beginner should start small, surely a smaller
> coil is easier to handle, physically, but a man has to do his thing,
> right?
>
> Cheers, Finn Hammer
>