Description Of The Block Diagram - Philips PM 3347 Manual

8
Description of the block diagram
(Fig. I )
The PM 3347 contains a complete time-base gen-
erator (TIME-BASE B), which regarding the con-
struction, largely resembles the time-base generator
of the basic oscilloscope (TIME-BASE A).
Besides the time-base voltage, the PM 3347 supplies
a delay pulse for starting time-base A at the basic
oscilloscope.
For this, the sawtooth voltage of time-base genera-
tor B is compared with an accurately adjustable d.c.
voltage (DELAY-TIME MULTIPLIER 1 : 10).
The output voltage of this comparator is applied to a
bistable multivibrator, which supplies the delay pulse.
INT
TRIGG
EXT
50 Hz
~—
AUT.
H F.
LF.
DC.
Tv-
FRAME
TV-LINE
LEVEL
Fig. 1. Survey of the controls
TRIGGER
PULSE
SHAPER
This delay pulse is applied to the time-base A gen-
erator via the output plug.
Starting of time-base A occurs at option, directly
by the delay pulse (STARTS A) or by the trigger
pulse (from the trigger unit of the basic oscilloscope)
after time-base A has been released by the delay
pulse (SETS A READY). The X-deflection voltage
is selected by means of a 3position-switch:
1 —time-base B
2 —time base B, while during the time that time-
base Aoperates, the trace is intensified
3 —the delayed time-base A.
TIME BASE
+GATE
~'
0
1.
TIME BASE B
I
2. I B INTENSIFIED BV A
3. iADEL'D BYB
I
I
I
J L ~ ~
~b
DELAY TIME
MULTIPLIER 1 : 10
TIME BASE
GENERATOR B
MIXER
4 2
'~n
i
3
X-PLUG
1
UNBLANKING
UNBLANKING "A"
DELAY TIME
or TIME/cm
LEN GTH
STAB.
VOLTAGE
COMPARATOR
TIME BASE
TIME BASE "A"
r STARTS R— -150 V
I
A
DEL'D
TRIGG
L
SETS A
READY
PULSE
SHAPER
DEL'D TRIGG
Q
to „STAB"
TIME BASE "A"
from „STAB" TIME BASE "A"
PEM 2785