Re: [TCML] 60/50Hz Tesla Coil? - Non disruptive

[Steve Ward <steve.ward@xxxxxxxxx>]

I seem to recall someone quoting Tesla (i know i know, "he said she said"
kinda stuff) along the lines of dreaming up some sort of AC alternator which
could produce an output frequency high enough for continuous oscillation of
his coils.  As far as using a tesla coil as a power transmission device,
this is considerably better than short bursts of high peak power, where the
crest factor is large, and as such resistive losses are disproportionately
high compared to the real power being processed.  Now, as far as making
sparks, transient operation is surely more efficient as far as real power
input vs spark length output.

But im not in this to argue over anything, im just pointing out some things
to think about.  I also do not know that the definition of a Tesla coil
requires a damped oscillatory discharge of a capacitor... if thats true then
i havent built a Tesla coil in a long time ;-).  Many of the systems i work
on use a quasi continuous excitation of the system, more like the analogy of
pushing the child on a swing, not letting go of the child after you managed
to get him 15 feet off the ground.

As to coils that dont operate transiently, here was one example i made a few
years back that operated in a continuous fashion, as if one were to plug it
into their 120khz wall outlet ;-)

http://www.stevehv.4hv.org/CWcoil/FWR31-2.JPG

The primary drive is a modest 300VAC.  You can download a video in the
parent directory at:

http://www.stevehv.4hv.org/CWcoil/

Its sort of like an x-ray transformers output rather than the loud
crash-bang of a SGTC.  If you put the primary cap back in, and pulse the AC
source over a long length of time, you can do wonderful things like this
(still, not capacitor discharge, but just resonance):

http://www.flickr.com/photos/kickermagnet/4386617170/

Im glad i wasnt stuck thinking about what a Tesla coil wasnt ;-).

Steve

On Tue, Apr 20, 2010 at 4:30 PM, Stephen Hiscock
<stephenhiscock@xxxxxxxxx>wrote:

> Steve Ward, I think you missed my point entirely - the capacitors are
> CHARGED over a long period of time and then DISCHARGED over a short period
> of time... hence the need for a "SWITCH" as you said...
> If you had read my whole post you would have read that I did write:
> "through a spark gap OR mechanical or electronic switching"
> All the designed you mentioned have CAPACITORS in the circuit.
>
> Steve ward also said "
>
>
> Many SSTCs are essentially driven by a high frequency voltage source, so if
> our mains frequency happened to be 10's of KHz, then it would be perfectly
> viable to plug your TC primary straight in, provided you designed the
> primary such that you limited the current draw via proper impedance
> matching
> to the streamer (not a hard thing to do).
>
> But the mains is NOT 10's of kilohertz its 50hz or 60hz.
>
> Are you saying that there are Tesla coils that DON'T have capacitors that
> are DISCHARGED?
> I would have thought that A Tesla Coil WITHOUT a primary capacitor
> DISCHARGING is NOT a TESLA Coil, its just a transformer!!!
> Just my thoughts though!
>
>
>
> Steve Ward wrote:
>
>> The only benefit i see to transient mode operation is for making long
>> sparks
>> with relative ease.  Other than that, it would seem to me that the main
>> reason for tesla coils being transient machines is that spark gaps were
>> the
>> only type of switch that would work.  In the real world of engineering, we
>> have a plethora of switches available to us, and tesla coilers have made
>> use
>> of them... vacuum tubes, thyratrons, SCRs, MOSFETs, BJTs, IGBTs, possibly
>> others.  Spark gaps just happen to be exceptionally easy to make work, and
>> thats perfectly ok if thats what the design needs.
>>
>> Many SSTCs are essentially driven by a high frequency voltage source, so
>> if
>> our mains frequency happened to be 10's of KHz, then it would be perfectly
>> viable to plug your TC primary straight in, provided you designed the
>> primary such that you limited the current draw via proper impedance
>> matching
>> to the streamer (not a hard thing to do).
>>
>> Steve
>>
>>
>> Some of the benefits of storing energy over a long period and discharging
>> it
>>
>>
>>> over a short period of time is the ability to harness the effects of
>>> massive
>>> peak currents (and the resultant magnetic fields that help to couple the
>>> primary and secondary together over large distances) and the massive peak
>>> energy levels which result in large streamers becoming visible. - this
>>> can
>>> result in peak powers of several MEGAWATTS
>>>
>>> now the mains is often not capable of providing thousands or even
>>> hundreds
>>> of amps - and even more so especially when the voltage is stepped up
>>> through
>>> a transformer this becomes practically impossible unless you own a power
>>> station.
>>>
>>> Hence this is one reason we use capacitors.....
>>> the reason we don't use 50 hz is because of physical size restraints and
>>> budgets.
>>> but basically IT WOULDN'T MATTER WHAT FREQUENCY THE MAINS WAS - we would
>>> NEVER PLUG A TESLA COIL DIRECTLY INTO THE MAINS - because we would lose
>>> the
>>> defining features of a Tesla coil. Even if we tuned it to 50 hz, it would
>>> only resonate at this frequency and would still not function as a
>>> disruptive
>>> discharge coil displaying the effects we associate with Tesla coils.
>>>
>>> stephen
>>>
>>> Greg Morris wrote:
>>>
>>>
>>>
>>>> So I just built my first solid state coil this year, and in thinking
>>>> about
>>>> the nature of primary circuit driving, I got wondering, wouldn't it be
>>>> possible to design a Tesla Coil in which the secondary resonated at (or
>>>> near) 60/50Hz? The primary coil could be plugged directed into the wall
>>>> with
>>>> no need for any driving circuitry, save for maybe a reactor to limit the
>>>> current.
>>>>
>>>> Thoughts? Has anyone tried this?
>>>>
>>>> Cheers!
>>>> Greg
>>>>
>>>>
>>>>
>>>>
>>>>
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>
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