Circuit
Description
—7D14
Fig. 3-2. Time Base and Control circuit control signal outputs.
DETAILED
CIRCUIT
DESCRIPTION
CHANNEL A
SIGNAL
CONDITIONING
General
A
detailed block diagram of the Channel A Signal Condi
tioning circuit
is shown in Fig. 3-3. The phase
relationship
between
the input signal and the
Clock output can be
selected
by
the SLOPE control to be in phase or out of
phase with
one another. When the SLOPE control is set in
the
positive-slope
region, the input signal is
in phase with
the
Clock output
signal. A schematic
of this circuit is
shown on
Diagram
1 in the Diagrams section.
Direct
coupling is used between
stages throughout the
Channel
A
Signal Conditioning
circuit (except the Trigger
Source
Amplifier). Feedback
from the output of the Trig
ger
Generator to
the minus (—) input of the Input Ampli
fier
through the Feedback Amplifier stabilizes the DC levels
of the stages
within the feedback loop. Thus, drift due to
temperature
offsets and/or bandwidth
switching is mini
mized. An
internal
Zero adjustment sets the voltage level at
the
plus
input of the Input Amplifier to adjust the quies
cent
DC levels of all stages within
the feedback loop. The
triggering
LEVEL control sets the current into the summing
point
at
the
minus
input of the Input Amplifier to provide
a
front-panel
adjustment of the Trigger Amplifier output
DC
level.
COUPLING
Switch
Signals
applied
to
the CH
A INPUT connector can
be
AC-coupled or
DC-coupled to the Input Amplifier. The in
put
coupling relay, K100, is actuated by COUPLING switch
S5.
When
the AC button is pressed, K100 is actuated to
pass the signal
through
C1 to the Input Sensitivity relays.
When the
DC button is pressed, K100 is
not actuated. The
signal
is connected
directly
from the CH A INPUT connec
tor
to
the Input
Sensitivity relays.
INPUT
SENS
Switch
Signals
to be counted are
applied to the
minus input of
the Input
Amplifier through
the CH A INPUT connector.
Input
Coupling Relay,
and the
Input Sensitivity relays; or,
to the
plus
input through
the Interface Connector (oscillo
scope
trigger
pickoff signal) and the Trigger Source Ampli
fier
stage. INPUT SENS switch S10 selects the signal input
and
sets the attenuation ratio/input
impedance for signals
connected to the
CH
A INPUT connector.
Switching
of the CH A INPUT signal is accomplished by
means of
relays,
K101-K103-K106,
actuated by S10. When
S10
is set to TRIG SOURCE,
+15 volts is applied to the
Trigger
Source Amplifier to turn it on.
At the same time,
the
switching
relays disconnect the CH A INPUT
signal
from the
Input Amplifier.
When
S10 is set to
the 100 mV sensitivity setting (50 Ω
or 1
MΩ), relays K101 and K103 connect the CH A INPUT
signal
from the Input Coupling Relay to the Input Ampli
fier. Resistor
R112 establishes a one-megohm input
impedance
in the 1 MΩ position of the INPUT SENS
switch.
A
network
consisting
of
R107-R108-LR108-R109-R110
is
switched in by relay
K106
in
the
50 Ω positions to provide a 50-ohm input
impedance.
R 1 01-R 1 02-R 1 03-R 1 04-R105
form a
10X-100X
attenuator
network.
C101-C102-C103-C105 compensate
this
attenuator
network for high-frequency signals. ForSW
3-3
Summary of Contents for 7D14
Page 4: ...7D14 ...
Page 11: ...Operating Instructions 7D14 Fig 2 1 7D14 front panel controls and connectors 2 2 ...
Page 33: ... 3 13 Fig 3 11 Logic diagram for Zero Cancel Logic stage Circuit Description 7D14 ...
Page 38: ...3 18 Fig 3 16 Time Base and Control circuit detailed block diagram Circuit Description 7D14 ...
Page 44: ...NOTES ...
Page 46: ...NJ Fig 4 1 Electrode configuration for semiconductors in this instrument I ...
Page 68: ...NOTES ...
Page 96: ... 7DI 4 DIGITAL COUNTER UNIT ...
Page 98: ...GRS 0371 BLOCK DIAGRAM ...
Page 99: ......
Page 103: ...0 0 I 200 mV 500 µs 0 001 200 mV 500 µs 0 001 MHz 00 mV E 00 µs 0 001 MHz ...
Page 106: ...1 ...
Page 110: ...A2 Logic Circuit Board Assembly jQ798i 798 jc743 CR744t uni R724 R742 JL744S FrR796 ...
Page 113: ......
Page 114: ...P 0 A2 LOGIC BOARD ...
Page 121: ... A B D t F H J NPR Tj ZWX V A AC M AEA HUM qAZ DEF HJ N P R S T J V V7X y ABM APAI AA 7DI4 ...
Page 129: ......
Page 130: ...4 7D14 DIGITAL COUNTER ...