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-
This stage produces positive and negative output d.c. voltages that are proportional to the positive and
*
negative top of the trigger signal. In the AUTO mode, these voltages are applied t o the two ends of the
LEVEL control R6. The input signal for the TOP DETECTOR i s derived from shunt feedback stage V863.
The positive top of this signal is rectified by diode V867 and smoothed by C872. The negative top is
rectified by diode V868 and smoothed by C873.
Both voltages are applied to the non-inverting input of an operational amplifier D852 (inputs 3 and 5). The
feedback loop of each amplifier is such that the gain i s one
followers with
Delayed Time-base Triggering (see Fig. 8.6.)
a ) Trigger selection circuit (A, B)
Series feedback amplifier V872, V874 receives the channel A signal for DTB triggering. Channel A is selected
DTB trigger source if R886 in the emitter circuit of V872, V874 is connected to earth via the DTB trigger
a
source switchcontacts S22A to make this stage conductive.
Series feedback amplifier V865, V895 receives the channel B signal for DTB triggering if R888 in the emitter
circuit of V865, V895 is connected to earth via switch contacts S22B of the trigger source switch, which
makes this
Trigger amplifier input stage
This i s
the DTB via channel A or B. The common-base circuit V921, V922'is followed by
This output signal is taken off asymmetrically from V923 collector and applied to the DC, LF, HF filter.
In the DC mode, switch contact S19A is closed and the trigger signal is passed via R1080 without frequency
attenuation.
In the LF mode, the d.c. path is interrupted and switch contact S19B i s closed. The signal is now passed via the
low-pass filter R1057, C929.
I n the HF mode, the d.c. path is interrupted and switch contact S19C i s now closed. The signal i s passed via the
high-pass filter C929, R1057. Both in the LF and HF modes, the d.c. component is blocked by the series
capacitor C931.
The asymmetrical voltage signal from the TRIGGER COUPLING
FET source-follower
As
a
by R4. This signal i s fed to an emitter-follower
circuit D854. The symmetrical output voltage signal on emitters D854-10 and D854-7 is applied to the series
feedback amplifier D854 (12,13,14) and D854 (2,3,4), with common-current source D854 (1.15.16).
The symetrical output current signals are available on collectors D854-12 and D854-2 and have
180 degrees. Depending on the position of the SLOPE switch S6, one of the
triggering by means of switching diodes: V910, V906 for
If the +SLOPE i s selected (S6 open), V906 is not conducting and the signal from collector D854-12 is routed
via diode V910 to the DTB.
Transistor V907 is not conducting and transistor V893 is therefore switched on. Diode V892 is blocked and the
connection between collector D854-2 and the DTB i s interrupted.
If the
away. Furthermore, diode V910 blocks and prevents any signal from collector D854-12 being passed to the DTB.
The positive voltage applied to the base of V907 from S6 causes this transistor to conduct, which then turns off
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transistor V893. As a result, diode V891 is blocked and the output signal on collector D854-2 i s routed via
V892 t o the input of the DTB.
--
a
high input impedance and
conductive.
stage
a
balanced input amplifier that accepts input current signals via soxkets X871 and X872 when triggering
L
stage
result, the source outputs of V919 show
is selected (S6 closed), diode V906 now conducts,
These operational amplifiers operate as emitter-
a
low output impedance.
stage is
receives a d.c. voltage, adjustable
gate
a
symmetrical voltage signal, the d.c. level of which is adjustable
D854 (9,10,11) and D854 (6,7,8), part of integrated
stage
+
slope, V892, V891 for - slope.
so the signal from collector D854-12 leaks
shunt feedback stage
a
applied to one
of the symmetrical
gate
by
the LEVEL control R4.
phase shift of
a
signals is selected for DTB
two
2-1 7
as
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