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Building Transformer & flux density





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From:  ESchulz531-at-aol-dot-com [SMTP:ESchulz531-at-aol-dot-com]
Sent:  Friday, June 12, 1998 12:36 PM
To:  tesla-at-pupman-dot-com
Subject:  Building Transformer & flux density

Hi,
	I am building a transformer for my tesla coil.  
I need to figure out the cross sectional area of the iron core.  
This would be related to max flux density in iron.

F stands for flux, A is area, 
f is frequency, N number of turns,
B is magnetic field, V is voltage

F = B * A

now for a close packed coil using faradays law
Emf = -d/dt * N * F

so if we substitute in for the flux F
Emf = -d/dt * N * B * A

Which can be rewritten as
V = f * N * B * A

Which can be rewritten as
B = V / (f * N * A)

ok I measured a NST and a H&R transformer and found
for NST B = 7.34 Tesla
for H&R B = 5.86 Tesla

5.86 and 7.34 Tesla seem kind of high to me.  Am I missing 
a factor or two?  Does this sound right?  Is all the physics good?

Thanks
Erik

p.s.  I actually remember some physics. ¦¬)