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Re: [TCML] Q





It's the primary Q that must be high. Richard Hull proved long ago that even a small "resonator" coil in a 3 coil system, the resonator was approx 4 inches x 34 inches, and was producing 11 ft long sparks, so the Q factor of the sec coil is really not that important.

Rich is not active on the list but I think Dave Sharpe may have some of this data.

Dr. Resonance

Resonance Research Corp.
www.resonanceresearch.com


----- Original Message ----- From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Sent: Wednesday, November 28, 2007 8:52 AM
Subject: RE: [TCML] Q


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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