Tektronix FG 5010 User Manual

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Except for the
polarity of Q1443
and the circuits
to which
this
circuit is
connected
,
the
Down
Ramp
Current
Source is
identical to the
Up
Ramp
Current
Source . For
further
detail
,
refer to
the
description of the
Up
Ramp
Current
Source
.
12
MAIN
LOOP
Introduction
Refer to Fig .
4-5 ,
which
is
a
simplified
diagram of
the
Main
Loop
circuits
.
The
Main
Loop
is
where the
triangle
wave
signal
is
generated
,
and also
the
squarewave . As
sume that the
Transistor
Bridge
is
operating
such that it is
directing
the
lup
current
to
the Loop
Capacitor
. This
means
that the
capacitor is
taking a
positive
charge
,
or
charging
in
a
positive
direction .
This
change in
voltage
is
passed
through the Triangle Buffer , which isolates the Loop Capaci
tor from
the
driven
circuits
.
The
Phase
Clamp
Diode
steers
current
from
the
node to
prevent the
Main
Loop from
free
running when gated , triggered or burst modes are chosen .
From
the
Triangle
Buffer ,
the
signal is fed
to
the
Triangle
Selector ,
which
selects
whether the
high
-
frequency
triangle
UP
SHRINK
1
DOWN
SHRINK
1
LF
TRIANGLE
LEVEL
DETECTOR
BRIDGE
BUFFER
from
the
buffer
,
or
the
low
-
frequency
triangle
from
the
Loop
2
circuits is to be
passed
to
the Sine
Shaper Circuits . The
triangle signal
also is fed to the
Level
Detector
,
which re
ceives the output currents from the Shrink Control circuits .
These
currents
modify the
point
on
the
triangle
signal
that
the
Level
Detector
switches .
When the
triangle
wave
reaches the proper voltage , the Level Detector switches ,
and the
transition is
coupled
to
the
Bridge
Buffer
,
which
drives
the
Transistor
Bridge and the
HF
Squarewave
Buffer
.
The
Transistor Bridge is
switched
by the
transition
, and the
current
is
fed to the
capacitor , and the
voltage at the
input of the Triangle Buffer begins to drop at a linear rate .
DN
The
Shrink
Control
currents
that
are
applied to the
Level
Detector
have the
following
purpose . As
the
loop is
required
to operate at
higher
frequencies , the loop begins
to lag . For
example
, at
a 20 MHz
triangle repetition rate , by
the time
the
Level
Detector
sees the
triangle rise
to the
planned
100 % point and switches the current in the Transistor
Bridge
,
the
Loop
Capacitor may
well
have
charged up to
110 % of
the
planned
value
.
This
affects both the
amplitude
and the
frequency of the
triangle
wave
.
By
injecting less
current in at
the
Level
Detector as
higher
frequencies are
selected
,
the
Level
Detector is
induced to
switch early
,
an
TRIANGLE
SELECTOR
TRIANGLE
BUFFER
HF
SQ
BUFFER
IUP
TRANSISTOR
BRIDGE
Theory
of
Operation
-
FG 5010
ION
Fig . 4-5 . Main
Loop
simplified
diagram
.
TRIANGLE
OUT
TO
PHASE
CLAMP
DIODE
ора
LOOP
CAPACITORS
HF SQ WAVE
TO
SQUARE
SELECTOR
3467-12
4-11

Tektronix FG 5010 Specifications

General

Brand	Tektronix
Model	FG 5010
Category	Portable Generator
Language	English