# Re: Continued Problems (fwd)

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---------- Forwarded message ----------
Date: Tue, 12 May 1998 19:41:26 -0700 (PDT)
From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
To: tesla-at-pupman-dot-com
Subject: Re:  Continued Problems (fwd)

"Hi Malcom,
Thanks for the info. If I am understanding you properly then if I were to
add a 1H coil to the primary side of a 100 to 1 ratio transformer it would
show up on the secondary side as an additional 100H inductance.
And if I were to put two 100 mH chokes on the secondary side they would
reflect back on the primary of the same transformer as 2mH.
Thanks again for helping me to understand
Bill Turbett
"
Impedance transformation goes as the square of the turns
ratio!  For your case 1 henry in the primary would be equivalent to
10,000 henries in the secondary!  Derivation is simple.  If the
transformer is 100 % efficient, and most are pretty close, the
secondary voltage will be multiplied by the turns ratio, while\
the secondary current will be reduced by the turns ratio.  (10:1
in voltage, for example, and 1:10 in current).  The secondary
impedance equals the secondary voltage divided by the secondary
current.  In this example, if the primary current and voltage
are 1 the apparent impedance looking into the primary is 1/1,
or 1 ohm.  The secondary voltage will be 10, and the secondary
current 1/10.  10 divided by 1/10 equals 100.

Ed

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