13—3.
RECTIFIERS
299
alternate half cycles, condenser ] is charged through switch
(tube) 1
,
then shares its charge with condenser 2, through valve 2;
condenser 2 shares its charge with 3 through switches ] and 3;
and 3 charges 4 through switches 2 and 4.
The rst condenser, near the transformer must be capable of
standing the peak voltage of the transformer and each of the
remaining condensers, as well as each rectier tube must stand
twice
this
value.
The
output
voltage is very nearly constant,
generalor
the ripple amounting to approxi—
|
_
mately 1% per
cent when the supply
,
frequency is 60 cycles per
second.
_
From theory and experiment it is
_
_
known that the ripple is inversely
| .
proportional to the frequency of
_
\
!
the supply line.
The wave form
vacuum
is similar to that of the half-wave
.
'
_
seal
doubler circuit, with one “saw- %
_…
'
tooth ”
per cycle. A peak voltage
ano-de
of 700 KV. has been obtained.
All of the rectier tubes of
mem] -…be
gure 13—5 can be contained in a
single vacuum chamber. In the J
tube
particular type7 shown in guré
__
_
13—6, the lament can be replaced
-
with case by pulling it out of
—_
—
its copper tube.
Since the la—
ments are at high potential, their
Fra. 13_6_
A high voltage rectier
currents
must
be supplied from
tube.
a
battery or a generator
which
is well
above ground and is surrounded by a
corona
shield.
The generator can be rotated by means of an 1nsulator
rod, as in the gure, or with a belt, from a motor at ground poten—
tial.
The tube is continuously evacuated, below approxrmately
10“4 millimeter of mercury.
Belt Generatom.—In the Van de Graaff electro—static generator,8
electrical charges of one sign are sprayed
onto &
€f_1d—
less belt made ofinsulating material and are carried into the 1ns1de
of a large hollow, metal sphere
where they are removed and, 1337