Panasonic Technics SL-1810

m= Explanation of each part
1. B.F.G. METHOD (BACK ELECTROMOTIVE
FORCE
FREQUENCY
GENERATOR)
3.
OPERATION
CONTROL
CIRCUIT
Making
use
of
the
back
electromotive
force
that
is
The
operation
control
circuit
functions
as
a
control
out-
generated
in
the
drive
coil
winding
of
the
motor
as
a
put
voltage
control
keeping
the
rotational
speed
of
the
frequency
generator,
the
frequency
of
the
frequency
turntable
constant
with
regard
to
the
start
of
turntable
generator
is
converted
to
the
number
of
revolutions
for
operation
and
the
operation
of
the
mechanism.
With
the
turntable.
this
circuit,
transient
response
characteristics
and
start-
After
shaping
the
wave
form
of
this
back
electromotive
ing
characteristics
are
very
good.
force,
it
is
composed
logically,
and
a
frequency
is
generated
that
is
proportional
to
the
number
of
revolu-
4.
OPERATIONAL
AMPLIFIER
(OP
AMP)
ACTIVE
tions.
This
is
the
use
of
the
B.F.G.
Making
use
of
the
FILTER
drive coil winding, frequency generator coil windings
and magnets are not necessary, yielding a motor struc-
ture that is very compact.
Because
of
using
an
operational
amplifier
in
the
active
filter,
an
ideal
filter
operation
is
possible.
As
a
result,
such
high
performance
as
a
signal-to-noise
(SN)
ratio
of
60
dB
(IEC-B)
and
a
wow-and-flutter
level
2.
FREQUENCY-VOLTAGE
CONVERSION
CIRCUIT
of
0.03%
(WRMS)
have
been
achieved.
Being
composed
of
a
trapezoldal
wave
generating
circult,
a
pulse
generating
circuit
and
a
sampling
integration
cir-
5.
DRIVE
CIRCUIT
cuit, the B.F.G. output frequency is converted to a vol-
tage, and control output voltage is generated in order to
maintain the rotational speed of the turntable at a cons-
tant level.
By
incorporating
a
large
capacity
power
transistor
in
the
integrated
circuit,
a
starting
torque
of
1
kg-cm
can
be
obtained.
By
means
of
this
large
starting
torgue,
prompt
starts
have
been
realized.
6. THREE DIFFERENTIAL SWITCHING CIRCUITS
By
means
of
the
signal
from
the
position
signal
coil,
the
Starting
circuit
power
transistor
selector
operates,
obtaining
smooth
rotation.
m@ Block diagram
Motor
|
Drive
Circuit
|
Mechanism
iC1
AN630
(1)B. FG
ae
ha”
ne
i
2
[
Frequency
Y
(8)
wm
Voltage
cometh
Detection
Signal
i oo Shaping Section
Logic
Wave From
Shaping
Circuit Gireult
Comparison Circuit
Bt+
Drive Coil
(3)
Operation
Control
Circuit
Oscillation
Circuit
Trapezoidal
Wave
(5)
Drive Circuit
Generating
Circuit
o—18)
ot
i ceiecoack
ey
arena
Standard
Signa!
Generating
Circuit
Differential
Switching
Circuits
Pulse
Integration Generating
Control Circuit
Output
Rotary Speed
Adjustment
Circuit
SL-1800/SL-1800A [5]
Position Signal Coil