[Prev][Next][Index][Thread]

Re: First Coil Works --Tuning Help

In a message dated 11/15/98 11:45:32 AM Pacific Standard Time,
tesla-at-pupman-dot-com writes:

<< 
 Thanks alot for everyones' help. I've learned quite a bit now about how
 these coils get in tune, and what to look for. With your help, I've
 calculated some data.
 
 My primary capacitance is very close to 0.0123 uf . Now, according to
 several programs I've run, my tank circiut will need a capacitance of about
 0.0212 uf. Soon I'll add another cap to the tank. (salt water,
 unfortunately.)
 My secondary resonates at 295kHz unloaded. But I've yet to find a program
 to give me an idea on where to tap out the 13 turn priamary to achieve
 resonance. Any Ideas? I have a 4.5" by 22" toroid which should lower this
 frequency considerably.
 The space between the edge of each turn is 7/16 of an inch. This makes the
 physical size of the coil rather large. I'm wondering if this might
 adversely effect performance.
 I'm also going to build a nice multiple air cooled gap. I have eleven
 polished copper electrodes at my disposal which makes ten gaps. I'll go
 with Ed's advice for gap spacing.
 Finally, I'll build some chokes and place a safety gap across the noens. So
 far I haven't had to pay a cent for my transformers. I'll try to keep it
 like that for a while.
 
 Thanks alot to everyone one the list who helps us novices,
 
 Adam
 p.s. Chris mentioned using 2L soda bottle caps. This sounds like a pretty
 good idea. Does anyone know how they handle the RF?
  >>
Adam,

Sounds like you are making good progress.  You haven't provided enough
information for me to do any calculations for you.  I use a spreadsheet that I
put together (it is available at Chip's web site and at the ftp site) to do my
calculations.  It is set up to first calculate the paramaters for the
secondary, then you input the primary information and it will calculate the
required tank capacitor.  I do all this first then play some what if with the
numbers, by for instance changing the number of turns input for the primary
until the calculated capacitance matches the amount of capacitance that I am
using.  This might be 10.5 turns - which is where the coil should tune, plus
or minus a turn or so.  It gets you in the right range anyway.  Another method
is to calculate how much primary inductance is needed in conjunction with your
capacitor to match the resonant frequency of the secondary - then use the
spreadsheet to vary input numbers to the primary calculations until you
achieve the required inductance.

Ed Sonderman