Re: [TCML] 1/4 wavelength theory ??

[mddeming@xxxxxxx]

Hi Shaun,

A TC behaves with some of the characteristics of a 1/4 wave resonator, wrt voltge and current distribution, but this is tied to the L and C values, h/d ratio, topload size, and only indirectly to wire length. It is almost unfortunate that a moderate size coil of average proportions CAN be made with a length of wire that turns out to be approximately 1/4 wavelength long. 
Matt D.






-----Original Message-----
From: Shaun Epp <scepp@xxxxxxx>
To: tesla@xxxxxxxxxx
Sent: Sun, Feb 7, 2010 2:33 pm
Subject: Re: [TCML] 1/4 wavelength theory ??


Thanks to all that responded to my questions.  
It's funny that some of the computer tesla coil programs still mention the 
opload capacitance to tune for 1/4 wavelength.  That's was why I ask this 
uestion.  
thanks,
Shaun Epp


----------------------------------------------------------------------------------------------------------------------------------------------------------------
ate: Sun, 07 Feb 2010 06:43:57 +0000
rom: Paul Nicholson <tcml88@xxxxxxxxxxx>
ubject: Re: [TCML] 1/4 wavelength theory ??
o: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
essage-ID: <4B6E612D.4000803@xxxxxxxxxxx>
ontent-Type: text/plain; charset=ISO-8859-1; format=flowed
The electrical length of the wire is shortened when it is
ound into a coil.
Here's a chap who got it right - back in 1994.  From the list
rcs,
  http://www.pupman.com/listarchives/1994/november/msg00041.html
dwp wrote (Nov 94):
> 1/2 wave of wire, wound as a solenoid, "looks/acts" like a 1/4 wave.
..
> The exact frequency will depend on the length to width ratio...
 > For tall skinny coils, it tends to 2-1.  For shorter fatter
> coils it tends back towards to 1-1 but does not get there.
Here's the actual curve which relates the wire's wound velocity
actor to that of the straight wire
  http://abelian.org/tssp/ph1.gif
All this applies to the unloaded coil.  If you add a big toroid the
requency will be pulled down a lot, maybe to reach near the frequency
xpected from the straight-wire.  This might explain some persistence
f the 'quarter-wave of wire' myth.
-
aul Nicholson
-
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