Seeburg LS 1 - Write-In Circuit

SE RVICE I\4 ANU AL
10- 22
Page
13
SELECT-O-MATIC
PHONOGRAPH,
Model LSI
The wrirein circuits
terminate
h
a
)6-Pir
plug, the
readout circuits
tetminate
in
80
rivets on
the bottoo
of
the meoory
unit and
the sensing
circuit
ter'
minates io
a single
p'rong connector
which
plugs
iato the trip
circuit o.r
the Solid State
Control
Center.
Each toroid has
tvo normal
states of magoetization
in vhich
the tesidual oagnetic
flux is io
either the
clockwise or couoterclockwise
direction.
One of
these states
is called
zero ot
no-selection;
the
other
is the selected
state.
If undisturbed
by a
magnetic field,
they
will retain, idefioitely,
eithet
state.
b.
Write-in Circuit
The
current
pulse and the resulta[t
magnetic field
that
passes through
a toroid oust exceed
a critical
deosity or strength
before the toroid
changes
state.
A
magnetic
field
less thao
the critical
value has oo
significant effect
on
the toroid. This
behavior
makes
it possible
to arrange the
toroids in a oattir
that
greatly simplifies
the
writein circuits and
writein switching.
Figure 7 shows
the oatrix,
circuits aod
switches
associated
with the writein
operation.
The circles
at the points of intersection of the letter and
oumber
circuits represeot the toroids. Any toroid
oay be identified in reference to the selection
nuobering system
of
the phonograph
by using
the
letter aod
number circuits that iotersecr io
that
toroid.
(Example:
Toroid 82
is
at the
intersectioo
of circuits B aod 2).
In Figure 7, selection 82 is shown
operated.
It can
be seen that
when
the trigger switch is closed, a
pulse
of current is fed through all the toroids in the
nuober 2 row. Froo the oumber 2 row, the pulse
enters the letter circuit and, since the B switch is
closed, through all the totoids in the B row, One
toroid,
82,
has dren been
pulsed
by a oagnetic field
twice
as
strong
as
any other toroid.
The cutrent pulse
is regulated in the Solid State
Control Ceoter so the curent through
a
siogle wire
does not produce
a oagoetic field
that
exceeds
the
critical
strength
required to select a toroid, ltris
means
that
even though a writein
pulse
is fed
through a
toroid, the toroid will not be selected uo-
less two circuits
are completed through it.