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Re: Square Wire
From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: Sunday, August 03, 1997 5:44 PM
To: tesla-at-pupman-dot-com
Subject: Re: Square Wire
Hi Jeff,
> From: Jeff W. Parisse[SMTP:jparisse-at-ddlabs-dot-com]
> Sent: Thursday, July 31, 1997 10:52 AM
> To: 'Tesla List'
> Subject: RE: Square Wire
>
> Malcolm,
>
> Your estimate of 950 turns is close. The measured TPI
> is 48 yielding a total turns of 960.
>
> You wrote:
> "According to my calcs based on estimated turns, L = 25.4mH,
> C = 9pF without terminal giving about 330kHz. How do those
> figures stack up with yours? What is measured L and f?"
>
> Fsec measured at 367kHz using a freq gen and a pair of leds
> attached to the base of the coil.
>
> How does one measure (and/or calculate) Lsec and Csec?
I use an inductance meter hooked across the secondary to measure L.
For a single-layer solenoid use WHeeler's formula to calculate it
(John Couture included it in one of his recent posts).
For Csec, measure F then plug L and F into the standard
equation to dig C out or you can calculate it using Medhurst's
formula Csec = HD where D = diameter in cm and H....
for h/d = 2, H = 0.51
for h/d = 5, H = 0.81
The relationship becomes a bit non-linear above this h/d but gives a
good indication nontheless.
It is beginning to sound like a shorted turn or two to me as well.
It can't be excessive capacitive loading or a hi-Z signal generator:
either or both of these cause F to drop beyond the correct value.
Malcolm