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The Block Diagram of the TEKTRONIX Type
513 Oscilloscope shows the major units and per
tinent waveforms present at various portions of
the circuit.
The diagram as shown has the trigger selector
switch in a position to accept external triggering.
The trigger inverter supplies a positive trigger
signal to the trigger amplifier regardless of the
input polarity to the inverter. The trigger ampli
fier applies an amplified negative signal to the
multivibrator and triggersit. The coupling diode
couples the amplifier and multivibrator together
during the negative trigger signal and then dis
connects them as soon as the multivibrator is
tripped. The multivibrator gates the sweep gen
erator and also generates an unblanking signal
for the cathode-ray tube. The sweep-generator
signal is amplified in a cathode-coupled phase
inverter amplifier which drives the push-pull
output sweep amplifier coupled to the horizontal
plates of the cathode-ray tube. The d c level
adjusters permit the d c level of the horizontal
deflection plates to be set properly while not
deteriorating the sweep sawtooth waveform.
The sweep magnifier, when switched into the
sweep circuit, amplifies the sweep generator
output by a factor of five to speed the sweep. By
means of a biasing adjustment, the level at which
output from the magnifier begins can be adjusted
so that any portion of the sweep can be magnified.
The unblanking amplifier amplifies the signal
from the negative-going half of the multivibrator
and applies it to the cathode- ray tube control grid
through a cathode-follower amplifier, so as to
turn on the cathode -ray beam during the period of
the sweep. The blanking multivibrator signal
overrides the unblanking multivibrator signal a t
the appropriate time when the sweep has just
completed. The blanking multivibrator is timed
BLOCK-DIAGRAM
TYPE 513 - CIRCUIT INFORMATION
INFORMATION
by means of a bias arrangement in conjunction
with the external sweep output sawtooth voltage.
The sweep output cathode follower also couples
into the bistable multivibrator comparator
through a cathode follower impedance converter
to provide a delayed gate output. The leading
edge of the delayed gate signal is differentiated
in the differentiating network and applied through
the cathode follower to trigger the blocking os
cillator. The output of the blocking oscillator is
available through a cathode follower at a front
panel connector as a delayed trigger signal. The
timing of the delayed gate and trigger is adjust
able by means of a biasing arrangement of the
bistable multivibrator comparator, so as to
occur at any desired point on the sweep.
The vertical input selector switch is shown in
a position to accept external signals. The input
attenuator provides several ratios of attenuation.
The input preamplifier is switched out except in
the two most sensitive positions of the vertical
input sensitivity switch. An internally-derived
trigger signal is provided by amplifying a portion
of the output of the gain-control cathode follower.
The delay network provides enough signal delay
to permit the sweep to get underway before the
signal appears at the vertical deflection plates.
The cathode follower transforms impedance
level to match the delay network input impedance.
The driver amplifiers are cathode coupled to
provide phase inversion for the push-pull distri
buted output amplifiers. The output amplifiers
drive the vertical deflection plates of the
cathode-ray tube.
The calibrator multivibrator provides a
square-wave voltage through the limiter cathode
follower to a calibrated voltage-divider network.
The limiter cathode follower is adjustable to
SECTION 3
CIRCUIT
3-1
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