
96-6 Displays and Recorders
resistivity ρ, and low magnetostriction coecient λ. Some of the properties for the commonly used core
ma
terials
a
re
l
isted
i
n
T
able
9
6
.2.
e evo
lution
of th
e
mag
netic
he
ad
fo
llows
th
e
se
lection
of co
re
ma
terials,
as sh
own
in Fi
gure
96.4. Ea
rly
he
ads
us
ed
la
minated
mo
lybdenum
Pe
rmalloy
(N
i–Fe–Mo,
79
–17–4
wt
%)
. e
se
he
ads
ar
e
in
expensive
to
ma
ke,
an
d
ha
ve
lo
w
H
c
and high μ and B
s
. e primary drawbacks are frequency limitation, gap dimen-
sion
in
accuracy,
an
d
me
chanical
so
ness
. Fr
equency
li
mitation
is ca
used
by th
e
di
culty
of ma
king
th
e
Ferrite core
(b)
Bonding
Coil
s
(a)
Laminations
Coil
Gap
Leads
MRF
θ
M
J
t
Core ...