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Re: 2nd coil



Tesla List wrote:
> 
> Subscriber: RRice43147-at-aol-dot-com Sat Jan 11 20:36:54 1997
> Date: Sat, 11 Jan 1997 20:59:11 -0500 (EST)
> From: RRice43147-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: 2nd coil
> 
> Hi everyone!
> My first TC turned out to be a design loser,
> the max. spark was 6",but i learned alot.
> One thing i learned was about this list and
> the knowledge of the people on it!
> For my next coil i want to use a 7.5" thin wall
> pvc form i have, along with a 15k 60ma neon.
> Before i begin,does anyone have suggestions
> as to wire size on the secondary and the primary
> type?I want to be able to increase the voltage later
> and use the same secondary.
> I know without a pole-pig i wont have a fire breathing coil
> but i want to maximize what i've got.
> 
> Thanks, Rick
> 
> My tc ckt,as i have it now:
> 
>                                                                        torrid
> 
>                                                              [[[[[[[[[]]]]]]]
>                            choke                                           \
>                  ------------(((((--------------------------o  o-----l
>        \
>   -------------- l                          l                gap     \
>        \
>  neon         : safty gap        cap                         \        \
>   -------------- l                          l                          \
>        \
>                  -----------((((((--------------------------------------l
>       \
>                            choke                                            \
> 
>  neon=4kvac
> choke=air wound 50 turns #6 wire
>              on 3/4" pvc
> main gap=air blast single gap
> primary=13 turns 1/4" copper tubing
>               6" to 18" saucer shape
> secondary=4" PVC 18"high with 1100
>                    turns 26 ga magnet wire(approx.)
> capacitor=.01mf cap from Plastic Cap.
> torrid=4" galvanized elbows/12" diameter


Rick:

First of all - a 15 KV 60 MA source should give you very good coil
performance! Some suggestions:

On your new coil, put the gap across the transformer and the tank cap in
series with the primary winding to reduce RF stress across the neon and
chokes. The chokes will then only need to block VHF parasitics from the
gap and supply circuitry. You need to have chokes with more inductance
(use magnet wire instead of #6 AWG - 300 turns on a 2" PVC form will
give you ablut 1mH). 

I wouldn't go smaller than 24 AWG, and 20-22 AWG is even better if
you're going to be boosting power levels in the future. Pretreat the
coilform by drying it and coating with several layers of clear
polyurethane. Coat the inside as well if you aren't planning to seal off
the ends. Make the coilform length at least 2" longer than the winding
length. Plan on 750-900 turns, tight-wound, which would mean about 26" -
29" of winding length, and 28" - 31" coilform length. This will give you
enough toroid-primary clearance, and allow you to increase power levels
later. After winding, use at least 6 coats of clear polyethylene, or
better yet, a single Behr Build50 epoxy coating. 

Make your toroids from pie-pans and smooth aluminum dryer duct. Its
cheap, looks nice, and works GREAT!.

Safe coilin' to ya!

-- Bert --