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Corrected definition of pancake R (formula OK)
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From: Thornton, Russ #CSR2000 [SMTP:ThorntoR-at-rc.pafb.af.mil]
Sent: Thursday, February 19, 1998 6:25 AM
To: 'Tesla List'
Subject: RE: Corrected definition of pancake R (formula OK)
>----------
>From: Tesla List[SMTP:tesla-at-pupman-dot-com]
>Sent: Wednesday, February 18, 1998 11:31 AM
>To: 'Tesla List'
>Subject: FW: Corrected definition of pancake R (formula OK)
>
>
>----------
>From: SBJohnston-at-aol-dot-com [SMTP:SBJohnston-at-aol-dot-com]
>Sent: Tuesday, February 17, 1998 11:23 AM
>To: aerpel-at-op-dot-net; tesla-at-pupman-dot-com
>Subject: Corrected definition of pancake R (formula OK)
>
>
>Alfred (aerpel-at-op-dot-net) wrote:
>
>>Below is the body of a post I can't get onto the Tesla list
>>because my email is screwed up, so you might not see it right
>>either. You were given incorrect information for pancake
>>primary inductance calculation.
>
>Yes... your email is looking a bit strange. Lots of control characters and
>stuff like: +AHw-. I'll post your comment to this list for you...
>
>Alfred wrote:
>
>>R is from the center of the pancake to the center of the
>>windings. This will only equal A/2 by accident.
>
>I cannot make out your ASCII drawing, Alfred, but here's a copy of Bert's
>orginal drawing...
>
> Center
> Line
> |
> O 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 O
> |
> |<----------------->|<--->|
> a b
>
>
> a = outer radius at turn "N" (inches)
> b = inner radius (inches)
> N = turn number
> R = Ave. Radius = (a+b)/2
> W = coil width at turn "N" = a-b
>
> L = (R^2 )*(N^2)/(8*R + 11*W) in MicroHenries
>
>
>
>Alfred, if I understand correctly you're saying the dimension R should be the
>average radius of the windings -- but the formula should be like this...
>
>
> Center
> Line
> |
> O 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 O
> |
> |<----------->|
> R |
> |<----------------->|<--->|
> a b
>
>If this big headache of mine is not blocking my algebra, your definition of R
>would be... R = [(a-b)/2]+b
>instead of R = (a+b)/2
>...right?
>
>Steve Johnston
>
>sbjohnston-at-aol-dot-com
>
>
>PS -- do you think it would help a headache to ground my body and use my
>Tesla Coil to send a few strikes into my head??? Not that I'm desperate or
>anything... but, whew.
>
Steve,
Now I have a head ache! :^) My math capabilities are probably the
lowest of the list but if I remember my math correctly both of your Rs
are the same.
R = [(a-b)/2] + b
=[(a-b)/2] + 2b/2
=[(a-b) + 2b]/2
=(a + b)/2 QED
Take 2 aspirin and call us in the morning. Hope you feel better!
>
>Russ Thornton
>CSR 2040,
>Building 989, Rm. A1-N20
>Phone: (407) 494-6430
>Email: thorntor-at-rc.pafb.af.mil
>
>
>
>