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*To*: Tesla Coil Mailing List <tesla@xxxxxxxxxx>*Subject*: Re: [TCML] inductance Vs diameter Vs height*From*: bartb <bartb@xxxxxxxxxxxxxxxx>*Date*: Thu, 12 Aug 2010 19:22:27 -0700*Delivered-to*: teslaarchive@xxxxxxxxxx*Delivered-to*: tesla@xxxxxxxxxx*In-reply-to*: <4C6496A4.4090006@xxxxxxxxxx>*List-archive*: <http://www.pupman.com/pipermail/tesla>*List-help*: <mailto:tesla-request@pupman.com?subject=help>*List-id*: Tesla Coil Mailing List <tesla.pupman.com>*List-post*: <mailto:tesla@pupman.com>*List-subscribe*: <http://www.pupman.com/mailman/listinfo/tesla>, <mailto:tesla-request@pupman.com?subject=subscribe>*List-unsubscribe*: <http://www.pupman.com/mailman/listinfo/tesla>, <mailto:tesla-request@pupman.com?subject=unsubscribe>*References*: <4C61B015.7090106@xxxxxxxxx> <10201F829D4B4F39BCEAD876EF17300C@Phillaptop> <4C6366DD.8080408@xxxxxxxxxxxxxxxx> <4C6496A4.4090006@xxxxxxxxxx>*Reply-to*: Tesla Coil Mailing List <tesla@xxxxxxxxxx>*Sender*: tesla-bounces@xxxxxxxxxx*User-agent*: Thunderbird 2.0.0.24 (Windows/20100228)

Take care, Bart Antonio Carlos M. de Queiroz wrote:

bartb wrote:Guys, I have a little spreadsheet for that graph I showed. It wasbased on h/d and Fr. My thoughts at the time is that this maxL wasalways based on a low frequency condition. Thus, I thought, whatabout when the coil is operating at Fr? Does that max inductanceratio still apply? The answer is NO. Of course not. Les is theeffective series inductance at the resonant frequency of the coil.And of course,, depending on Les for your specific coil, the maximuminductance attainable is different than the standard ratio so oftenreferred to.So often, coilers forget that our coils have an operating frequencyand the inductance at that AC is not 50 or 60 Hz. Inductances doeschange with frequency and thus, so does maximum inductance for ageometry.It's not very correct to say that "inductance changes with frequency".What happens is that a coil is not just an inductor. It is acombination of distributed inductance and capacitance, not countingresistance. The impedance seen across the coil is inductive at lowfrequency, tending to the DC value of the inductance, but at higherfrequencies the distributed capacitances contribute more and more tothe impedance. If you consider just the value of the reactance andattributes it to a single inductor, the equivalent inductor reallyappears to change with the frequency. In the simplest model, agrounded vertical coil seen from the top has a capacitor in parallelwith it. As the frequency rises, the impedance grows to a maximum(infinite in the lossless case) at the resonance frequency of thecombination. At frequencies below the resonance the reactance ispositive, and equivalent to the reactance of an inductor larger thanthe one seen at DC.Antonio Carlos M. de Queiroz _______________________________________________ Tesla mailing list Tesla@xxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla

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**Follow-Ups**:**Re: [TCML] inductance Vs diameter Vs height***From:*Paul Nicholson

**References**:**[TCML] inductance Vs diameter Vs height***From:*Scott Bogard

**Re: [TCML] inductance Vs diameter Vs height***From:*Phil Tuck

**Re: [TCML] inductance Vs diameter Vs height***From:*bartb

**Re: Re: [TCML] inductance Vs diameter Vs height***From:*Antonio Carlos M. de Queiroz

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