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Re: Bonsai



Original poster: "S.Gaeta by way of Terry Fritz <twftesla-at-qwest-dot-net>" <sgtporky-at-prodigy-dot-net>

Herb,

I absolutely love it!!! I am a big fan of little coils. You can do a lot
with them, and they tend to be more photogenic than big coils. I have built
a few of them, notably the Radical Radio and The Fix which can be seen at:
http://community.webshots-dot-com/album/1865657rQpDLUevFH
I have noticed that you can pump alot of current into these things. I have
driven a 3" by 6" with 90 mA with no ill effects, but when I try to go above
7.5KV I get racing sparks on the secondaries of any secondary shorter than
13". Five kv seems to be the limit on my 1" by 4" 'Fix' secondary (my
smallest).

It truely is amazing to see a little coil produce large streamers for it's
size!

Please be careful with the corona on the floor. I actually did burn a hole
in a rug once while playing with a solid state HV ocillator. A 40kv cable
was attached to the output and a 1" thick block of silicone rubber was used
to prop it off the rug. Nothing happened for a long time, but then finally I
smelled something burning as my experiment drew to a close. The tiles of the
floor in your case are acting as the dielectric part of a capacitor, and
that is how the RF is getting to ground. RF sees a capacitor as a very low
impedance. My capacitor dielectric at the time of my little accident was the
40 kv rated silicone insulation on the cable, and the silicone block. I had
no RF knowlege at the time, and thought this would stand off a couple
hundred KV!!

Sue

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, July 31, 2001 3:04 PM
Subject: Bonsai


> Original poster: "Herbert Mehlhose by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <herbert.mehlhose-at-kdt.de>
>
> Hi all,
> last weekend I finished my new coil model. I call it BONSAI because of
> its size: secondary diameter is only 3cm, about 1.2inch, toroid diameter
>
> is 12cm (4.8 inch). You can see a description on my homepage:
> http://home.wtal.de/herbs_teslapage/index.html
> Go to the link "Model 3".
>
> There are interesting points I found:
>
> 1. The coil performs quite well, (streamer length of 6inches and more)
> although
> its frequency is about 1MHz and power is very low. I had expected less
> due to high losses
> because of this high frequency and low power.
>
> 2. As BONSAI only has very low power (using a 7.5kV/50mA NST) and a
> 2.2nF MMC
> cap made of  10 PHILIPS KP/MMKP 376 caps, I tried to use the coil in my
> apartment
> where I do NOT have an RF ground (my larger models are used in the
> garden of my mother,
> where I have built an RF ground, but it is always 100km to drive there).
>
> Although I do not have an RF ground, the performance seems not to
> suffer. I also
> noticed this on other tests with my Model 1b. Maybe RFI may be an issue
> but also
> for this, I did not find a real increase, at least for TV sets or radio.
> I will also do tests with
> BONSAI using the RF ground, when I will visit my mother next time.
>
> 3. Instead of an RF ground, I only used a vice, normally used for table
> mounting
> and connected the secondary base to it. A brass rod clamped in this vice
> has been used to
> draw the streamers (putting it far away causes the toroid to discharge
> into the air).
> This way I built a "closed ciruit" for the streamers: Current drawn from
> the vice, going up
> the secondary to the toroid and from there to the brass rod back to the
> vice ....
> When firing the coil, this vice draws continous sparks to the floor
> where it is lying on. Even the
> isolated wire, connecting the secondary base to the vice shows some kind
> of corona to the floor
> without burning any holes. See the pictures on my homepage...
> How can this effect be explained? For drawing sparks or corona effects,
> I think there is a potential
> difference needed. Where does this come from in this case? Some kind of
> capacitive effects
> which work well due to the high frequency?
> All in all, my impression is, that I have still a big lack of
> understanding. Looking forward to
> learn again....
>
> Tell me what you think about BONSAI, and thanks you for any ideas,
>
> Cheers,
>        Herb
>
>
>
>