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Re: Atomic Laboratories 71869 Tesla Coil

Original poster: Stan <wsmg@xxxxxxxxxx>

Hey Pete,
I assumed(bad thing) your coil was one of those little coned ones and thought 2" to 3" streamers was doing pretty good. Seeing what you actually have is a different story. When you open your spark gap your risking frying the transformer(no Terry filter or safety gap), secondary(arcing from primary breaking down the secondary insulation), and more capacitors(as you found out). Like Matt said you could modify it but how far do you go. It looks like you have room in the case for a mmc bank and you could unwind some off the bottom of the secondary and you could mount a primary on top of the case and add a safety gap. It would be a good class project. What are the actual dimensions of the secondary? I see a tag on the tranny, does it give a voltage and current? Another note, you may have already broke down the insulation on your primary. You could try winding a primary with a little more gap between the secondary and a higher voltage cap and add a safety gap. 

Hope this is alittle more help then my original reply,
Stan

Tesla list wrote:


Original poster: "Peter Birk" <birk@xxxxxxx>

Not sure about amperage.  Using a variactor and multiplying the output I
estimate the tranformer puts out 7 or 8 KV.

Grounding is still not settled.  There was a problem with shocks and sparks
from the metal case.  I found this defective capacitor and parallel
resistors connecting the bottom of the coil to the metal case.  This in turn
was connected to the ground wire on the power cord.  I disconnected the
capacitor and tried running the bottom of the coil to an earth (water pipe)
ground.  Also tried connecting both the coil and the case to the water pipe
ground.  Never could get the case where it could be touched comfortably.
I'm beginning to think it just can't be done to due induction effects and
limitations of water pipe grounding.  I'm planning to connect the bottom of
the coil to a jack on the case and provide 'em with a cable to clip it to a
ground.  The metal case has to stay connected to the power ground for
safety.  There doesn't seem to be any problem using a power strip with a
switch to switch it on and off to avoid touching the case.

Pete

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Saturday, November 04, 2006 5:37 PM
To: tesla@xxxxxxxxxx
Subject: Re: Atomic Laboratories 71869 Tesla Coil


Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

How many amps does it eat? How long were the sparks before it died?
Just a guess but doesn't look like it was built for efficiency with
the long skinny secondary (built for portability and durability).
Might not shoot more than a foot by design. What are you using for a ground?

Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, November 04, 2006 2:51 PM
Subject: RE: Atomic Laboratories 71869 Tesla Coil


>Original poster: "Peter Birk" <birk@xxxxxxx>
>
>Fired up the coil after the changes suggested.  Works better but still can
>only draw about a 8 - 10 inch spark.  No more sparks from the case. Noticed
>a lot of sparking between the primary and secondary despite the quarter
inch
>thick plastic tube and the rubbery primary casing.  Its much worse if the
>spark gap is widened over about 1/8 inch.  The primary coil is centered 4
>inches from the bottom of the secondary.  I wonder if raising the secondary
>to bring the primary closer to the bottom will help this. Here's what it
>looks like:
>http://hot-streamer.com/temp/PeterBirk/IMG_0134_7_9_1.JPG
>http://hot-streamer.com/temp/PeterBirk/IMG_0136_5_9_1.JPG
>
>Stan I appreciate your comments.  This list is dedicated to coilers turning
>out technically and aesthetically elegant machines.  I impose on your time
>and patience because I need expertise not available elsewhere.  This coil
is
>old but solidly built by a reputable company - CENCO.  It survived 30 years
>of use in a public school - I call that proof of design.  If I can get it
>going another 10 years several thousand students will see it and perhaps a
>few will be inspired.
>
>Thanks
>Pete
>
>-----Original Message-----
>From: Tesla list [mailto:tesla@xxxxxxxxxx]
>Sent: Friday, November 03, 2006 10:39 PM
>To: tesla@xxxxxxxxxx
>Subject: Re: Atomic Laboratories 71869 Tesla Coil
>
>
>Original poster: Stan <wsmg@xxxxxxxxxx>
>
>Hey Pete,
>    I'm thinking that all the time you have been trying to get this
>classroom science lab coil to be better then it was designed to be,
>you could of wound a small coil  with tunning capablities and had
>more fun. Those were designed to be cheap and be safe for a
>classroom(nothing wrong with that). I'm sorry to be so negitive, but
>they aren't as inspiring as a real coil. Kids these days need to be
>inspired.
>   Please don't be offended, I'm not an expert, I've only been coiling
>for just over a year since going to D C's 05 Teslathon, but I have
>come a long way. Check it out.
>http://www.ispdial.com/SkyXPRess_net/MyHomePage/config.cfm?kName=wsmg
>click on pictures to the left. That's just a few pics, we are working
>on a DVD that will be much better. If you need a free nst  I have a
>bunch of  6k, 7.5k, 25ma with the wires that come off of them
>(old)  that work  just pay the shipping.  If your interested contact
>me off list.
>
>Stan
>
>
>Tesla list wrote:
>
> >Original poster: Mddeming@xxxxxxx
> >In a message dated 11/3/06 7:16:53 P.M. Eastern Standard Time,
> >tesla@xxxxxxxxxx writes:
> >
> >While it was apart I tried to measure the resonant frequncies with a
>scope
> >and signal generator.  The primary dips at 217 kHz.  The secondary dipped
>at
> >245 kHz.  I found the top ball was not electrically connected.
With that
> >connected the secondary dips at 236 kHz.  I wonder if anyone has any idea
>of
> >how to tune this coil.  Note the primary is encased in rubbery compound.
> >
> >Thanks
> >
> >Pete from Virginia
> >
> >
> >hi Pete,
> >
> >Since streamer formation tends to pull down the secondary frequency,
> >you are probably very, very close to where you want to be without
> >additional tuning.
> >
> >Matt D.
> >
> >
> >
>
>