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Re: Secondary Q
- To: tesla-at-xxxxxxxxxx
- Subject: Re: Secondary Q
- From: Terry Fritz <twftesla-at-xxxxxxxxxx>
- Date: Tue, 07 Nov 2000 14:26:28 -0700
- Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme
- In-Reply-To: <20001106.084557.-45465.0.kcha1-at-juno-dot-com>
When you consider that maybe 40% of the coil's power is lost in the gap,
the overall system Q is going to be bad... If one looks at the Q loosly as
total energy divided by energy lost, 100 / 40 = 2.5
At 08:39 AM 11/6/2000 -0800, you wrote:
>2.48?...A Q of 2.48?? I am shocked!...shocked! Here, during all these
>years of thinking about Tesla coils--over 60 of them, I will have you
>know!--I've been under the misapprehension that Tesla-coilers depended
>upon, cherished and highly valued...resonance! But no..., no..., no...
>Q?...who needs it? Resonance, even...who needs it? With the power and
>voltage of a Grand Coulee or a TMI or even, in better times, of a
>Chernobyl, coupled thru a vast pile of pole pigs, who needs resonance?
>I've always likened Tesla-coilers to those profound Asian monks who
>ritually bong upon their magnificent bronze gongs. But no, most of you
>just pour on the coal. While I strive to maximize output while
>minimizing input, your goal is to maximize output while maximizing input.
>Who cares if you can fry eggs on your secondaries? It keeps the shop
>warm. Q of 0? Not a problem!
>Disillusioned in California,
>On Sat, 04 Nov 2000 17:21:12 -0700 "Tesla list" <tesla-at-pupman-dot-com>
>> Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
>> Hi Kennan,
>> Disruptive coils have very low over all Q. My big LTR's is about
>> 2.48 as
>> shown in the graph at:
>> This is how we can load up streamers and do other frequency altering
>> and still get good output.
>> I think the discussion of Q really comes down to losses in
>> coils. Since I used Sonotube, my streamer length may be about 5%
>> less than
>> if I had used PVC. A surprising amount of power is going into
>> heating the
>> cardboard. As you note, our voltage amplification is by impedance
>> transformation rather than pure resonant ring up.
>> Of course, 5% is not a super big deal but the loss is surprising. In
>> humid place, it may become a real problem. In a CW coil, heating
>> become a real issue since the tube could get hot enough to burn if
>> you are
>> really pushing a lot of power into the system. Q is far more
>> important in
>> the CW case.
>> BTW - Tesla had some nice CW coils too in teh 1900's that ran off
>> frequency alternators. However, unlike our disruptive coils today,
>> would not recognize most of the parts of today's solid state
>> Tubes were the "modern" thing in his time so he would not have a
>> with that ;-))
>> At 01:30 PM 11/4/2000 -0800, you wrote:
>> >There's been a bit of discussion of secondary Q recently that leads
>> me to
>> >ask how all you 19th-cy. spark-gap types (the vast majority!)
>> manage to
>> >utilize decent Q at all: Your tuning is imprecise due to
>> difficulty in
>> >getting primary resonance to match that of the secondary; and
>> >also--certainly when using a secondary with a Q as high as 80-100,
>> >I've measured for mine--because the secondary's resonant frequency
>> is not
>> >only "hard to find" but also it is going to shift markedly whenever
>> >conducting surface gets anywhere near it. You've got two resonant
>> >circuits searching for each other, so to speak, with not a whole
>> lot of
>> >continuing success, I should think.
>> >I'm aware of the assertion that the energy stored in the primary
>> >capacitor gets put into the secondary capacitance, less that lost
>> due to
>> >gap loss and to primary:secondary coupling inefficiency. So if the
>> >capacitance ratio is 100:1 and you start out with 10KV on the
>> primary one
>> >then theoretically you end up with a respectable voltage in the
>> >secondary's capacitance prior to the zap. But where, then, does
>> >resonance come into it, and how are you going to gain,
>> particularly, by
>> >having a high-Q secondary?
>> >Perhaps I'm too much of a purist but I stick with my s.s. system in
>> >there's only one resonant item, the secondary, and that item itself
>> >the resonant element in a feedback primary-driving oscillator
>> >Always spot-on, resonance-wise, cycle by cycle. So with my scheme,
>> >higher the Q the better since higher Q facilitates higher voltage
>> >build-up prior to the spark.
>> >Ken Herrick
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>YOU'RE PAYING TOO MUCH FOR THE INTERNET!
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