HP 400D Operating And Servicing Manual page 17

due to the presence of harmonics in the waveform
of a voltage under measurement.
This table is universal in its appllcation since these
iullt�nml in all
errors are
ment of the average responding type.
The current flow through the rectUier-meter circuit
in
is shown Figure 3-2. For purposes of explanation,
the amplUier (tubes V2-V5) may be considered as a
signal generator with the output from the plate of
V5 as one side, and the cathode of V2 as the other
side. The rectifier-meter circuit may be considered
as a bridge across the generator.
half of the cycle, current flows into the bridge from
"
' R2 2
CIC
I
R2 l
-
FROM VI
R82
R28A
270
Figure 3-2.
voltage measuring equip­
On
the positive
+
CI1 A
V3 -V4
-
020
R29B
R28B R29A
Model 400D/H/L Direction of Current Flow through
RectUier Meter Bridge
On
the top. the negative half of the cycle, current
flows into the bridge from the bottom.
On of
the positive half
and current flows through CR
tween the meter and capaCitor C32, where it divides,
a portion placing a charge on capaCitor C32 and the
rest flowing through the meter. Since diode CR2
is non-conducting, the current from the meter output
flows to capacitor C33, placing a charge thereon.
As capacitor C32 and C33 discharge, current flows
to the generator.
On the negative half of the cycle, diode CR2 is
and
biased to conduct,
The current flowing into the bridge at the juncture
between capacitors C32 and C33 divides, half placing
a charge on C32 and the other half on C33. Since
LEGEND
DIRECTION OF CURRENT
n
,
\
\
/
'
CR'
V5
---+
--
+
-
-
/
1\
,
I
\
,
, \ '
-
'
Partial Schematic
III
Sect.
the cycle, diode CRI conducts,
to the juncture
1
diode CRI is non-conducting.
FLOW
POSITIVE HALF 0'
CYCLE
0'
CYCLE
NEGATIVE HALF
0'
POSITIVE HALF CYCLE
HALF
0'
NEGATIVE
CYCLE
/
,
,
,
- +---
•
. ,
'
, ,
,
,
CH
---+
" '
\
RlS C
SO -L -1 1
Page 3
be­
-
--- ..
n
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