Re: Twin Coil Systems.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Parpp807-at-aol-dot-com>

In a message dated 1/27/02 11:19:39 AM Central Standard Time, 
tesla-at-pupman-dot-com writes:

> Original poster: "Neil Richardson by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" 
> <neil-at-opticalrealities-dot-com>

Hi Neil,
(I assume I am writing to Neil. Please sign your name to your postings so we 
can
properly address you.) 
I have just completed a twin bipolar coil and I am still playing and trying 
to learn.
This twin has evolved from my horizontal bipolar. Note that because of the 
horizontal
configuration, I used a helical primary. I assume you will wind a flat 
Archimedes spiral. It makes no difference with the twin. You can see pictures 
of my horizontal bipolar at

http://hot-streamer-dot-com/temp/RalphsCoil/

The bipolar was simply cut in half to get two resonators and two primaries.
Your coils should be physically and electrically equal.

You will discover that the tuning of the twin coil is most cantankerous and
tricky. you will have fun and you will learn. 

>>>>>I was thinking of building one with a friend since they produce longer 
arcs,
>  and basically look nicer :)<<<<<

Longer than what? The twin requires a lot of room. Mine is setup on the 
basement floor. At 73-75 inches of unstable blue spark, it is throwing sparks 
into the clothes 
washer and up to the duct work. It's a beast. I can calm it down to a tame 
65-68
inches of white spark. A twin needs a lot of room.

>>>>I was wondering - do the primaries have to be connected in series or
>  parallel. I was thinking of parallel, but if they weren't tapped at exactly
>  the right point, the system would not work. In series, I would add the 2
>  inductances right?<<<<<

The primaries are connected in series with the lower ends (inner for an 
Archimedes)
across the SG and HV source. Tune upward (out) with Cp. Yes, Lt = L1 + L2,
but you tune with the tap.

You gotta tune the primary circuit separately. The series primaries are tuned 
to F res. Tune them far away from the secs. Connect Cp across the series 
connected primaries and tune for F res. You are tuning a paralllel resonant 
circuit.

>>> And about the secondaries - I know you must wind one
>  clockwise, the other counterclockwise,<<<<<<

Nope. Same direction but it really does not matter. You will phase the 
primaries
which are also wound in the same direction. Don't worry about it. If the 
primaries are connected wrong, you will not get anything. Just reverse the 
connections. No
problem. The fun starts when you have to tune this creature. :-)) Start out 
by making two identical primaries and secondaries.

>>> and connect their grounds together -<<<<<

Yes, the secs are grounded together. I use the powerline ground.  :-((

>  but what about their inductance and self capacitance? Would they be like 2
>  capacitors in parallel or series? Cos if I plan to build a twin coil system
>  I need to know how to make it work well first time, I want my first real
>  tesla coil attempt to be something to show off about :)

Ls and Cself + C top will determine F res. This will depend on your coil and
its topload.
You have a circuit resonating at the F res for the secondary with the topload.
   
Happy day,
Ralh Zekelman