Tektronix FG 5010 User Manual

Theory
of
Operation -
FG
5010
segments will be cutoff . This protects the segments against
the excessive current that would otherwise be applied to a
single segment if the cycling stopped .
The output of U1232B is fed through U1234B , which per
mits blanking control of the display by the CPU circuit . The
output of inverter U1234A , pin 1 , is the complement of the
one - shot output plus the blanking input . The inverter drives
Q1136 , which provides the required current gain for follow
ing circuits . When the base of Q1136 is pulled low , it con
ducts to change the impedance at the base of Q1135 to be
the
parallel
combination of
R1132
and
R1133
. When
Q1136
is cutoff , R1133 is the Q1135 base impedance . Transistor
Q1135
,
capacitor C1131 , and
resistors
R1132
and R1133
form a Miller Integrator . This smooths out the sharp transi
tions from Q1136 that would otherwise be passed to the
Segment Driver stages . When conducting , the collector of
Q1135
furnishes the drain
current paths
through resistor
pack R1131 for the Segment Buffer stages , Q1121 through
Q1134 .
4-62
Decoder U1230 converts the SLO , SL1 , and SL2 signals
from three - line to seven - line , one of which signals is not
used . Cycling time for the three input signals is on the order
of 5 ms , so each of the output lines is low for about 640 µs .
These lines successively enable each column of the front
panel
keyboard
for
sampling by
the
CPU circuits
.
Segment
Buffer
The SEG 1 through SEG 8 signals from the CPU enter
the Display Driver board through P1110 pins 9B , and 12A
through 15B , respectively . From there , each of the signals is
applied
to the gate
of a field effect
transistor . These
are
Q1121 through Q1134 . Drain current for these stages is
supplied by Q1131 through R1131 , as explained earlier .
From the source of each stage , each signal is applied to a
common emitter integrator output stage . The integrator ac
tion reduces sharp transitions that would introduce noise
into the rest
of the
instrument
.
U
U
U
U
U
U
U
U
U
U
U
U
U
U

Tektronix FG 5010 Specifications

General

Brand	Tektronix
Model	FG 5010
Category	Portable Generator
Language	English