2)
Explanation
of the circuit operation
(Refer
to
Figs.
6, 7)
The
velocity
signal obtained
from
the motor's
frequency
generator
is shaped into a waveform in
the
period
of
"T"
proportionate
to the velocity as
in
(a)
on collector TR6. This signal is
differen-
tiated and enters TR7 base. This makes TR7's
collector output as in
(c)
and turns ON TRl0
during the time of the negative
pulse.
Meanwhile TR8 base is
supplied with a waveform
like
(d)
and when it reaches the threshold
level,
TR8
is turned on. A waveform
(e)
with
pulse
width
"11
"
is obtained
from
the collector. During
the time
"T"
that
TR28 is ON, TR9 base electric
potential
decreases to turn ON.
Consequently, TRI I
base
electric
potential
inèreases
and
TRI I
is also
turned
ON
for the
time
"tr ".
When
the
period
"T"
varies
with the
velocity,
the
pulse
width
"t1
"
varies according
to TRS's
threshold
level.
But when
TRl0 is
on,
it
is con-
stant due to
the
time constant.
So
that
by using
the
period
that TR
is ON as
the
standard
pulse,
the
pulse
width
"t2
"
is constant
regardless
of the
velocity.
(g)
and
(h)
show
the
ON and OFF condition of
TRl0 and TRll. When the electric
charge
that
was charged to
C16
is
discharged during
the time
TRl I is ON
"t1",
a signal voltage of
"e"
propor-
tionate
to
the velocity can be obtained.
Next,
with
"e"
as its basis, Cl6 is charged
during
the limited
time of the standard
pulse
width
"t,
",
and by the
charging voltage
"e"
the
charging
is
stopped.
The voltage is then
held
until the
hext standard
pulse.
This
voltage
"e"
is supplied
to the TRl2
base and
a servo signal
"E"
is obtained. This servo
signal
"E"
controls
TR13 and drives the motor.
As
shown
above,
since
"tt "
and
"t2 "
are small,
servo signal ripples are made small and a near
direct
current servo signal
is
obtained.
In
addition,
the
time constants of the
smoothing circuit can
also be made
small
that
phase
lag
factor
can be
minimized.
22
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