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Re: Colorado Notes and laser caps
At 11:25 PM 2/7/97 -0700, you wrote:
>> Subject: laser caps
>> Subject: laser caps
>
>Subscriber: tom_mcgahee-at-sigmais-dot-com Fri Feb 7 23:09:09 1997
>Date: Fri, 7 Feb 1997 17:36:52 -0500
>From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Colorado Notes and laser caps
>
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>----------
>> From: Tesla List <tesla-at-poodle.pupman-dot-com>
>> To: Tesla-list-subscribers-at-poodle.pupman-dot-com
>> Subject: laser caps
>> Date: Friday, February 07, 1997 2:25 AM
>>
>> Subscriber: gweaver-at-earthlink-dot-net Fri Feb 7 00:17:33 1997
>> Date: Thu, 06 Feb 1997 08:39:52 -0800
>> From: Gary Weaver <gweaver-at-earthlink-dot-net>
>> To: tesla-at-pupman-dot-com
>> Subject: laser caps
>>
>> see attachment
>>
>> [ Part 2: "Attached Text" ]
>>
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>> Today at the scrap yard I found what I think is a power supply for some
>type of laser. The tag said Laser Products, Mesa, Arizona. The power
>supply has 28 door knob type capacitors. They are mounted in 2 groups of
>14 caps each in parallel. Each group is mounted side by side and the ends
>of the caps all have a single spark gap on the end connecting each cap of
>one group to the matching cap of the other group. It has 14 spark gaps.
>The caps and gaps are mounted inside a 1/2" plastic case with 4 fans on the
>side of the case for air flow. All 4 fans are 4" box fans also sometimes
>called muffin fans. The case also has a small freon type cooling system
>built inside. On top of the case is a high voltage transformer, some type
>of amplifier device, another control box, a 40,000. volt .06 uf plastic
>cap, several high wattage resistors, a choke coil, a high voltage ignition
>coil device simular to a car ignition coil large orange plastic, gas flow
>control valves and guages and lots of other items. The thing weive never
>seen anything like it and I have never thought of making such a device. I
>have not given it any thought yet but it may be useful in TC applications.
>Enclosed is a circuit drawing.
>>
>> Gary Weaver
>> [Part 3, Image/GIF 7.7KB]
>> [Unable to print this part]
>
>Gary,
>The 14 spark gaps may indicate that the caps are wired in what is sometimes
>called a Marx configuration. Are there any coils connecting the caps? If
>there are, then what you have is a form of high voltage Multiplier circuit.
>Many people are familiar with the Marx multiplier circuits that use
>capacitors and rectifiers. Well, there is a form of the Marx multiplier
>that uses coils and capacitors. The way it works is this: The capacitors
>are initially connected in parallel with one another via the
>inter-connecting coils. (the coils can be just a couple of turns of wire...
>it doesn't take much!). When the capacitors reach a certain critical
>voltage at least one of the spark gaps conducts. What happens then is very
>interesting. ALL the spark gaps will fire simultaneously and the currents
>will cause the coils to build up a very high opposition to this current
>spike. The result is that for a fraction of a second the capacitors that
>had been in parallel now ACT like they are in series. Since the voltage
>drop of the spark gaps is LOW when they are conducting, this results in a
>VERY HIGH output voltage pulse.
>
>Now, before everybody starts thinking "Off the Topic, what has this got to
>do with Tesla Coils?" let me say that in 1964 I saw a very large Tesla coil
>that was part of a traveling science show. The coil threw about six foot
>sparks, which was quite good for a Tesla coil in those days. After the show
>I pestered the people responsible for the show until they reluctantly let
>me look at the thing up close. Inside a big metal box was a bunch of coils
>and capacitors. When I asked the guy what all that was about, he explained
>to me that it was a coil-capacitor Marx multiplier used to step up their
>couple of KV main transformer voltage up to 30KV. I should mention that
>another thing that made this Tesla coil somewhat unconventional was the
>fact that the resonating capacitor was connected directly in parallel with
>the primary of the Tesla coil. The Marx multiplier would dump a nice big
>bunch of energy into the L/C primary circuit, and then the primary would
>happily ring away until it was hit again by the next dump of energy. Note
>that this strange Tesla coil was a pulse-driven design with no topload
>other than a flat copper plate on the top. And *that* was there so that the
>performer could stand on top of the coil and throw sparks off of metal
>electrodes on his hands. If these guys had bothered to put a toroid on this
>baby, it probably could have done much better. Also, this was the *only*
>Tesla coil that I had ever encountered that had a capacitor connected
>directly in parallel with the primary. When I got home I pulled out my most
>prized possession, a book published in 1956 on the occassion of the 100th
>aniversay of Tesla's birth by the Nikola Tesla Museum in Beograd,
>Yugoslavia. This book is a huge compendium of Tesla's lectures, patents and
>articles, entitled "Nikola Tesla * Lectures * Patents * Articles" that
>comprises about 600 pages of material written by Nikola Tesla. It is not a
>book about Tesla, but rather ALL of it is material written BY Tesla.
>Excellent stuff! Anyway, at the absolute end of this huge book is a
>photograph of a page from Tesla's Colorado Springs notebook. And there is a
>hand drawing by Tesla of a Tesla coil circuit in which one capacitor is
>used to produce the disruptive discharge, and the other is placed directly
>in parallel with the Tesla primary.
>
>I was reminded of this L/C arrangement by a recent remark made by Richard
>Hull in one of his postings here on the Tesla list. And then today this
>Laser power supply with its multiple spark gap thing reminded me of the
>first time I ever saw such a circuit, and how I had thought the designer
>must have made some sort of mistake, because their Tesla coil was so
>different from all the ones I had information on, only to discover that
>Tesla had done the same thing many years earlier.
>
>There is still room for fruitful modern research based on such little
>things from the past. We may be tempted to just pass by, look at it with a
>shake of our head and say "boy, those guys weren't as smart as us." Some of
>them, like Tesla, were even smarter than we think. And that includes those
>of us that think he was a genius.
Thomas
The book "Nikola Tesla - Lectures, Patents & Articles" by Nikola Tesla,
1956, two volumes, over 1000 pages is back in print $65.00, available from
Borderlands, P.O. Box 220 Bayside, California 95524, Tel 707 825-7733, Fax
708 825-7799, E-mail www.borderlands-dot-com
Gerry Vassilatos has an article in the Borderlands - Quarterly Journal of
Borderland Research, Second Quarter 1996, title The Broadcast Power of
Nikola Tesla - Part 1. An excellent biography with reference to the Marx
generator that Tesla called "impulse transformers" and how Tesla used it for
impulsing an electrostatic field in his coils.
Tesla remarked that the electrostatic potentials along the coil surface
(from end to end) could be as much as ten thousand volts per inch winding! A
ten inch coil of proper volume could produce one hundred thousand volt
discharge. In addition, and in confirmation of his suspicions, no current
was ever measured at the free terminals of these coils. A "zero coil
current" condition!
Michael