Re: My Secondary
On Wed, 10 Apr 1996 09:00:54 +0700, tesla-at-grendel.objinc-dot-com, you
>>From MALCOLM-at-directorate.wnp.ac.nz Wed Apr 10 01:23 MDT 1996
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<tesla-at-grendel.objinc-dot-com>; Tue, 9 Apr 1996 22:50:41 -0600
>From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
>Date: Wed, 10 Apr 1996 16:50:35 +1200
>Subject: Re: My Secondary
>On the subject of extremes I was interested to see this from Scott
>> I wrapped the coil around a 4' long cardboard tube with 8.5"
>> diameter. I did not paint it with any kind of finish to make it
>> more of an insulator. I also made a rather larger mistake in using
>> (and this is the kicker!) #34 wire. So now I have a 4' long 7000
>> wind inductor and I was wondering if there is any way to make a
>> working tesla coil out of this or do I just have a big piece of
>> junk. Any suggestions would be grealy appreciated.
>My suggestions: I would try it out of sheer interest before pulling
>it apart. BUT, I think the tube should be thoroughly dried and
>impregnated with varnish before firing. My guess is it would smoke at
>any appreciable power level due to the thin wire insulation (volts
I concur with malcolm, fire her up! just realize the smoke is
the working fluid of all electrical components; if you let the smoke
out, it stops working;)
You might consider getting 2 plastic waste paper baskets, hot gluing
the large ends together, and winding it with some larger wire. Get
this secondary going, before trying the more fragile cardboard one.
> I calculate : inductance about 1.7 Henries!
> : self capacitance about 19pF
> : bare resonant frequency about 28kHz !
> I would expect its Q to be moderate due to the high wire
>resistance and cardboard. But I reckon there must be a hundred and one
>interesting experiments you could perform with it and I would love to
>hear from others who have contemplated things to do with low
> Ny prime suggestion : acquire a more suitable former for a serious
>coil and in the meantime, let's see what ideas there are for this
>somewhat unique opportunity. For example, if you tuned it to 8Hz with
>a capacitance of 233uF, you could "listen" in to the earth's natural
>resonant cavity (guess).
If we all start building 1 megavolt caps, how long do you
think it will take to get 233uF;)
>Extra capacitance of 130pF (additional to the
>19pF self-C) gets it to resonate at 10kHz (within hearing range). I
>must admit to wondering what a coil really sounds like :)
At 10Khz, why not tune it into the US Navy submarine communication
system? One might be able to light a couple of NE2s with it.