Re: newbie TC questions

Hi Jan,

At 05:32 PM 08/24/1999 +0300, you wrote:
>Hello coilers,
>here's one more newcomer to TC! 
>I live in the capital of Finland, Helsinki, (it's not so cold as some
>might think, the summer was burning hot, but today just 26C though 8-).

Welcome to the Tesla list!

>I've been experimenting with ignition coils and tv flybacks for a while
>now. Seeing all those cool discharge pics and reading through the
>archives I thought about building a very small TC for starters, with a
>secondary diameter of just 1.18" or maybe 2". 
>Tomorrow I get one or two NSTs, for free. Can't still believe it, 
>first call at a neon sign company was a success!

I like many people started out using ignition coils too.  They don't give
very good power at all but they are easy for the very beginning.  Sounds
like you had great luck with the NSTs.

>It would be great if you could give me some tips on the secondary coil
>design, if I am on the right tracks with this mini secondary form size?
>diameter 2", height 10"
>648 turns of AWG 27 emalled copper wire

That sounds a bit small to me but for a nice little first coil it should be
ok.  You didn't mention the voltage and the current of the NSTs (you may
not know till you get them).  If they put out a lot of power the small coil
may get overwhelmed.  Of course, if you have a variac, you can control the
power as needed.

>Before I forget it there's one thing that I'd be glad if someone could
>help me with. That "magnet wire" for winding the secondary has me
>puzzled. Is it just plain, normal, varnished copper wire? If not, what's
>it made of and what would be a place to get it?

It is just plain old enameled wire used in motors and everything else with
electromagnet type windings.  I get mine from an electric motor repair
shop.  They can order anything I need over night.  Since they rewind
electric motors, they have a lot of magnet wire and are usually happy to
sell it outright with a usually rather high markup ($5/lb).  I can search
the Earth and get it much cheaper but they are super convenient so I just
get it from them.

>Oh, I've still a few questions (sorry if they seem boring or plain 
>stupid... ). Here they are anyway:
>a) should the secondary's RF ground really be connected to the center tap
>of the NST in the design in which the RF ground is also in the
>middle of the safety gap? It seemed odd to me because wouldn't the toroids
>discharge strike straight away into the primary as it is connected to the
>ground over a 4.5kV potential (for a 9kV NST)?

Find a good ground like a water pipe or ground rod and connect everything
that "should" be grounded to it.  The grounds are meant to protect you,
first of all, from electric shock.  If the streamer hits the primary, the
safety gaps should protect everything from damage.  The NST will be
protected by overvoltage by the safety gap but the streamer probably will
not have enough current to really hurt anything in the primary anyway.  I
may not have completely understood what you were asking here...

>b) may the RF ground be connected to the drainage/water pipe system, or
>the wall outlets ground, or, should it be an additional ground made with
>pipes hammered into earth. (hard to do from here, it's 3 floors down ;)

I would NOT us the AC wall outlet grounds.  They are connected directly to
all the other electrical devices in the home.  Having 20 amps of RF current
running into that ground could damage something.  Waste pipes often have
rubber seals between section and may not have a solid electrical connection
along their route to ground.  If the cold water pipes are all solid metal
to the ground then they would be a possible choice for a small system.  I
would open the window and run a big wire directly down to a grounded rod

>d) are ignition coils and rectified tv flybacks useful at all for powering

I used to run single pulse coils with them.  You get a spark every second
or so but they are nothing compared to a real NST powered system.  I still
use ignition coils for testing...

>hope my english was readable, and the questions not too boring = too
>anyway, many thanks folks,