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Re: loose coupling
Subject:
Re: loose coupling
Date:
Mon, 17 Mar 1997 05:46:11 -0700
From:
"DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
To:
"Tesla List" <tesla-at-pupman-dot-com>
To: Rob Davis
If the coupling exceeds a critical value the secondary frequency begins
beating, ie, operating at two separate frequencies instead of at the
fundamental. This beating effect begins slowly and then builds if the
coupling is increased beyond a certain value. This effect is best
illustrated with a graph and a good source to actually "see" this
information is in the ARRL Amateur's Radio Handbook which is usually
available in any medium to large size public library. Their description
is
very good and the graphs make the point much easier to comprehend. The
older issues are usually the best.
This dual frequency operation usually extends equally either side of the
fundamental resonant frequency and draws away the energy transfer from
where you really want it, ie, the fundamental resonant freq. of your
secondary inductor.
In many small coil systems the secondary inductor must be elevated as
much
as 3-5 inches above the flat spiral primary inductor to achieve best
operational results. There are ways of accurately testing these effects
but the usual procedure is to begin slowly elevating the secondary coil
with the unit operating at 30-40% power (using a variac). By carefully
adjusting both the primary tuning tap and the elevation of the secondary
inductor you will achieve best results with maximum energy transfer from
your primary to secondary system.
For safety's sake be sure to unplug the unit from the wall outlet during
each adjustment. Don't trust a switch or relay with the high potentials
involved.
Good luck.
DR.RESONANCE-at-next-wave-dot-net
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-poodle.pupman-dot-com
> Subject: loose coupling
> Date: Sunday,March 16,1997 9:55 PM
>
> Subject:
> loose coupling
> Date:
> Mon, 17 Mar 97 04:14:27 UT
> From:
> "Robert Davis" <Davis_Lewis-at-msn-dot-com>
> To:
> tesla-at-pupman-dot-com
>
>
> Hello, I am new to the list and am in the process of designing and
> building my first (small) coil and have a couple of questions.
>
> I am a little puzzled as to why Tesla coils should be loosely
> coupled. Is
> this due to the high turns ratio (for the extra voltage gain, although,
> as I
> understand it most of the voltage gain is due to the Q of the secondary
> at
> resonance) resulting in a high secondary inductance compared with the
> primary
> or that the degree of flux linkage between the primary and secondary
> should be
> low for some reason?
>
> I have also found difficulty in finding a good book on Tesla's work,
> could
> anyone recommend a suitable title.
>
>
> Thank you in advance, I look forward to receiving your reply(s).
>
> Rob Davis.