RE: [TCML] Q

["Lau, Gary" <Gary.Lau@xxxxxx>]

Hi Bart,

I've not yet scoped this coil to confirm your xfer time estimate.  I'm curious how you arrived at that figure, since I didn't include detailed specs for primary construction and coupling geometry parameters.  Probably just a set of good guesses based on the photo?

It wouldn't surprise me that high frequency coils with conventional coupling figures have xfer times proportionally shorter. I would guess that it all scales - could be that for coupling value X, 1st notch occurs in Y cycles regardless of frequency?  And I have no doubt that reducing the coupling to an atypically low value would reduce performance for the same reason that it would on a conventional low-frequency coil.  A lower coupling would require the gap to burn for a longer interval for each notch, resulting in higher gap losses.

I'm not convinced that secondary resistance and Q are worthy of heroic measures to improve them.  The secondary current is small and resistive losses are low.  I recall that Terry did an extensive analysis of loss components, and the secondary was not high on the list.  The primary Q however IS vital.

Regards, Gary

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Barton B. Anderson
> Sent: Tuesday, November 27, 2007 10:19 PM
> To: Tesla Coil Mailing List
> Subject: [TCML] Q
>
> Hi Gary,
>
> I've been looking at your coil specs a tonight. I don't know if you have
> equated it but the transfer rate is really fast at 1.7us! Although this
> little coil is similar physically to the norm, that Mhz range really
> increases the transfer rate significantly. I wonder how the coil would
> work under a more typical transfer rate say in 10us or so?
>
> The only way you can alter that is to reduce coupling. I'm kind of
> curious if the high frequency and transfer rate is an area we are
> overlooking with these small coils? We always seem to build them
> physically the same (scaled down), but we are not accounting for the
> frequency and di/dt which is associated with it.
>
> In your case, due to the 38 awg wire size, there will be some large AC
> losses. Even though transfer rate is quick, the Q is only about 144 on
> this coil. This is what I was trying to explain about high frequency
> coils with normal turn ratios.
>
> I kind of doubt a reduced coupling would do better due to the Q and
> secondary losses.
>
> Take care,
> Bart
>
>
> >> --- "Lau, Gary" wrote:
> >> Hello All,
> >>
> >> I have finally gotten around to documenting my Bug
> >> Zapper Transformer (BZT) powered coil on my web
> >> site. For those interested, please see
> >> http://www.laushaus.com/tesla/bzt_coil.htm
> >>
> >> Regards, Gary Lau
> >> MA, USA
> >>
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