Re: Magnifier coupling measurements, new (fwd)
---------- Forwarded message ----------
Date: Fri, 10 Jul 1998 09:36:05 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Magnifier coupling measurements, new (fwd)
Thanks for the further measurements of magnifier k's. I
have two comments: Firstly, the overall k of my system was almost an
order of magnitude below the driver itself because the driver
secondary had such a small fraction of total secondary inductance.
Driver Ls was about 350uH and resonator around 7mH if memory serves
> ---------- Forwarded message ----------
> Date: Tue, 7 Jul 1998 09:10:48 EDT
> From: FutureT-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Magnifier coupling measurements, new
> In these tests, I looked at the primary current waveform by using
> a current transformer attached to an oscilloscope. These tests
> provide further verification that despite the tight coupling of a
> magnifier driver, the overall coupling of a magnifier is loose, and is
> typically within the range of two-coil Tesla coils. (In my previous
> tests, I looked at the secondary or extra coil waveforms.)
> I used the same old set up with pri, 19 turns, # 12 wire, sec, 1.5mH
> 6.5" dia by 3.4" high, # 24 pvc, driver k = .4, extra coil = 11.4 (13?)mH.
> 3" by 12" # 28 formvar, tank cap = 0.0015uF, Fo = ~500kHz, toroid is
> 1.5" by 4.5", synch gap 8 point series quench type, (4 points used),
> powered by 10kV, 23ma oil burner ignition transformer. A variable tune
> cap (34pF to 167pF range) is installed across the secondary.
> Figuring the effective or actual coupling based on a 28uS beat, gives
> k = 0.07 which is quite a low figure. But it compares well with Malcolm's
> results where his 0.54 driver k fell to k = 0.086 actual overall system k.
> Also interesting was the appearance of the secondary (?) waveform.
> It did not show normal energy transfers, but rather had a flat
> shape (except at the beginning), but I may have been picking
> up some of the extra coil's energy, and this may have given a false
> appearance to this waveform?
I think you may be picking up some of the primary. I too found this
problem confused my results until I realised what was happening and
repositioned the probe and coils. ?perhaps?
Thanks for an exceedingly interesting post.