First progress report on a multi-channel magnetic drum inner ...

whence
j
V > e = -N
e d t . NJ
dt
d$,.. = const
IV-2
3) In any head design part of this flux^, strays uselessly about
the conductors of the winding, giving rise to a "leaikage" self-inductance
"L" while the remainder ^i links the material to be inscribed and gives
the inductive effect "l". This separation of the total flux into two
components suggests an equivalent network representation of the recording
head by means of the two inductances "L" and "1" in series j it being
understood that "L" has a fixed, non-retentive flux path while "1" has
a moving core of high retentivityj the problem of design is then to
absolutely minimize "L" and to maximize a particular functional aspect
of "1"; this aspect depending upon the characteristics of the recognition
process applied to the read-out signal,
A) Consider now an electrical conductor lying near a magnetizeable
surface — any magnetizeable surface, either that of a core assembly or
that of t he recording medium proper. If the separation of the axis of the
conductor from the surface be "d", then the field intensity at the nearest
part of the surface can readily be calculated, and is in fact:
21
H = -^-r- oersted.
Clearly both the local intensity of magnetization of the surface, and the
total flux produced in the surface are greatly increased as "d" is reduced;