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There
are three
RC
networks connected
to pin
1
and
three
RC
networks connected
to pin
4
of IC1.
These
six
RC
networks
provide frequency response
compensation
for
ICl
and
the
entire
loop of the
Triangle
Generator
so that
it
wiil
have
a
flat
frequency response
from
dc
to
10
MHz.
The
fiip-flop
is
comprised
of
transistors
QIO
through
Q16,
with
Q12
and
Q13
connected
as
a
differential
pair.
Q14
supplies a
constant
bias
to the
differential pair,
preventing
saturation
during
their
"on"
state.
Q1
1
and
Q16
are voltage
followers
whose
output
is
fed
back
to
Q12
and
Q13
through
R46, R54, and
R55
forming
the
flip-flop
configuration.
Q9
is
connected
as
a
7-volt
zener reference
for
ICl
and
the
flip-flop.
In
the
state
where
Q13
is
conducting
and
Q12
is
cut
off.
the voitage
at
the emitter of
Q16
is
high (+2.5
V)
and
the
voltage at the emitter
of
Q11
is
low
(—2.5
V).
Once
tunnel
diode IC13
is
turned
on by
ICl, the
V^e
of
Q15
will
increase
until
Q15
turns
on and
in
turn
Q13
is
turned
off.
This causes the emitter voltage of
Q16
to
drop
to
—2.5
V
which, through feedback
resistors
R47
and R46,
keeps
Q12
in
the
on
state.
Thus
the emitter voltage of
Q1
will
rise
to
+2.5
volts.
Although
the tunnel
diode
CR13
is
turned
on
only
a
very
short
time during
the
peak
of the
triangle
waveform,
Q13
will
remain
in
the
off state
because
of the
feedback
tiirough
R46, R47, R54, and R55.
The
output
of
Q1
1 is
used to
drive
the diode
gate.
DIODE
GATE
As shown
in
Figure
3-7,
the
Diode Gate
consists
of four
diodes,
CR7
through
CR10. Assume
that the voltage
at
point
C
is
+2,5
V.
Diodes
CR7
and
CR9
are
then forward
biased,
and
CR8
and
CR10
are reverse biased.
The
negative
current source
(I—)
will
draw
current
from
the
Hysteresis
Switch through
CR9,
but
the
positive
current source
(1+)
will
charge
up
the timing capacitor
"C"
through
CR7.
Figure 3-7
-
Simplified
Diode Gate Diagram
The
result
is
a
linear
rise
of voltage across the timing
capacitor.
When
this
voltage reaches
+1
.25
volts,
the
output
of the Hysteresis
Switch
will
change
to
—2.5
volts.
In
this state.
CR8
and
CR10
are
forward
biased
and
CR7
and
CR9
are reverse biased.
The
positive
current
will
be
diverted
to the Hysteresis
Switch through
CR10
and
the negative
current source
will
draw
current
from
the timing
capacitor
through
CR8.
This
action causes a
iinear
discharge of the
timing
capacitor.
The
process
is
repeated,
thus
a triangle
waveform
is
generated.
SINE
CONVERTER AND
AMPLIFIER
The
Sine Converter
is
a sealed
subassembly
containing
matched
diodes and
precise current-biasing
resistive net-
works.
When
a
precise
triangle
wave
is
fed
into
the
shaping network, through
voltage divider
R149
and
RMS,
the
triangle
wave
is
shaped
into
a sine
wave. Potentiometers
R159
and
R168
adjust
the voltage supplied to the
sine
converter
to
obtain
minimum
sine distortion.
The
ampli-
tude
of the
sine
converter
output
is
approximately
250
mV
p-p.
This
voltage
is
amplified to
approximately
2.5
V
p-p
by
the Sine Amplifier.
The
Sine Amplifier
consists
of
transistors
Q30
through
Q35
connected
as
a
differential
feedback
amplifier.
The
gain
of
the
amplifier
is
controlled
by R165, R164,
and R158.
R145
and
R146
compensate
the source current
into
Q30
to
minimize
the distortion of the
sine
converter output.
SQUARE
AMPLIFIER
The
inverted
output from
Hysteresis
Switch
Q16
(±2.5 volt
square
wave)
is
fed to the
Square
Wave
Shaper comprised
of
CRM
through
CR19.
For
a
square
wave
output,
CRM
and
CR19
are reverse biased.
In
one
state,
if
the
cathode
voltage
of
CR15
is
+2.5
volts,
CR15
and
CR17
will
be
reverse
biased
and
CR16
and
CR18
will
be forward
biased.
The
output
at
the
cathode
of
CR18
is
limited
to
+1.25
volts
by
the current dirough
R63
and
R64
into
R69.
When
the
input voltage
is
switched
to
—2.5
volts,
CR15
and
CR17
will
be forward
biased
and
CR16
and
CR18
will
be
reverse
bia^,
limiting
the
output
at
the
cathode
of
CR18
to
—1.!^
volts
by
the current through
R66
and
R67
into
R69.
When
the
positive pulse
output
is
selected
by
the
WAVE-
FORM
SELECTOR
switch, the
cathode
of
CRM
is
con-
nected to
ground through R61.
In this
configuration, the
output
at
the
anode
of
CR18
will
be
limited
to
a
voltage
swing
of
—1.25 and
zero.
Because
the
output
amplifier
is
an
inverting
amplifier,
the
signal
at
the
50^
OUT
connector
will
be
a positive pulse. In
a
similar
manner,
when
the
anode
of
CR19
is
connected
to
ground through
R61,
the
output swing
at
the
cathode
of
CR18
will
be
3-8
12/70
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