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RE: [TCML] Inductive and Capacitive reactance - units of measurement
Brian,
Greg has good ideas. Another great idea is to buy a Radio Amateur's
Handbook. It doesn't need to be a new one - these principles have not
changed for decades. The Handbook is a great resource to learn the basics.
The emphasis is more on the practical applications than the theory. EBay
sometimes has used ones for sale.
--Steve Y.
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of G Hunter
Sent: Sunday, March 07, 2010 7:49 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Inductive and Capacitive reactance - units of
measurement
Hi Brian,
I feel your pain. My replies are interspersed with your questions below...
--- On Sun, 3/7/10, Brian Hall <brianh4242@xxxxxxxxxxx> wrote:
> From: Brian Hall <brianh4242@xxxxxxxxxxx>
> Subject: [TCML] Inductive and Capacitive reactance - units of measurement
> To: tesla@xxxxxxxxxx
> Date: Sunday, March 7, 2010, 3:11 PM
>
>
>
> When planning/tuning a TC, to get XL = XC, inductive
> reactance = capacitive reactance in both the primary and
> secondary, I know is one of the goals, for the primary L and
> C and the secondary L and C to match
>
>
> so if:
>
>
>
> XL = 2(pi)FL
> where
>
> F=Frequency
> L=Inductance
>
>
>
> and
>
>
>
> XC = 1/(2(pi*FC))
> where
>
> F=Frequency
> C=Capacitance
>
>
> -what units of measurements are those formulas intended to
> be used with, for frequency in Hz/kHz/Mhz, inductance in
> henries/microhenries/some other henries, and farads,
> microfarads. nanofarads, picofarads etc? How do they
> vary between parts commonly used in the primary and
> secondary portions of the circuit?
The capacitive and inductive reactance formulas are meant to be used with
whole units, yielding an answer measured in Ohms. Farads and Hertz are used
for Xc, and Henries and Hertz for XL. For example, calculating Xc for 1uF
and 1Mhz: That's the reciprocal of 2(pi) x .000001F x 1,000,000Hz = 1/6.28
Ohms = .159 Ohms. The ENG function on a TI-30 calculator makes electronics
math much easier.
>
>
> For example I know that the topload is usually in pf and
> the tank cap usually in uf .... so some unit conversion will
> be required, but what?
u(micro) = 1/1,000,000 n(nano) = 1/1,000,000,000 and p(pico) =
1/1,000,000,000,000. Conversion between units is easy. Just move the
decimal three places. For example, .001u = 1n = 1000p
>
>
> Also I know that frequency is determined by the number of
> turns and the size of the winding, but in the tank circuit
> there is also the frequency at which the spark gap
> fires. Which frequency is referred to, that of the
> primary coil dimensions, or bps of the sg, or some mix of
> both?
The tank circuit resonates in the radio frequency range, usually hundreds of
kiloHertz. The spark gap normally switches at 10s to 100s of breaks per
second. The two aren't really related.
>
> and once I can crunch the numbers to determine how to
> adjust the parts to make XL=XC for the primary, and the
> secondary
>
> -What unit of measurement is XL and XC reactance measured
> in, for both inductive and capacitance, and how does its
> unit conversion work for meaningful numbers in contruction
> for optimal performance?
They are measured in Ohms. At the resonant frequency, Xc and XL cancel out,
so don't worry too much about their respective values.
>
>
> And to put each tuned LC together, for tank and tower,
> should the XL of the primary = XL of the secondary, and
> likewise, XC of the primary cap = XC of the topload?
No.
>
>
>
> (btw I tried JavaTC and it seems too complicated ... the
> dimensions of the room in which it will be run are unknown
> so that kind of affects on the rest the numbers .. so i dont
> trust the numbers it gives me, nor do I understand what
> every field on that form means, and I know there has to be
> an easier way - i like the simple calculators on
> deepfriedneon.com that take it one part at a time for
> frequency, MMC and such)
>
>
>
>
> ----------------------------------
> Brian Hall
>
Brian,
I have a suggestion. Locate a primer on basic electronics, including metric
units and engineering notation. You can find such a primer at the book
store or library, or for free on-line. If there are chapters on DC and AC
principles, read them both. A couple of hours of reading will probably
clear the fog for you. It takes me about 100 classroom hours to teach DC
and AC basics, starting with the theory of electric current and ending with
an introduction to LC filters. I don't think TCML is an appropriate forum
for a 100-hour lesson! Besides, I'd bore you so badly you'd probably
abandon the hobby. You can learn what you need to know with a couple of
hours of targeted reading. E-mail me off-list if I can help.
Cheers,
Greg
http://myweb.cableone.net/grcarhunter
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