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Patented May 16, 1944
'2,349,225
UNITED STATES PATENT ` OFFICE
2,349,225
`
' WELL LoGGmG INSTRUMENT
Serge Alexander Scherbatskoy, Gilbert l Swift,
Robert Earl Fear-on, and Jacob Neufeld, Tulsa,
Okla., assignors to Well Surveys, Incorporated,
Tulsa, Okla., a corporation of Delaware
Application September 15, 1941, Serial No. 410,954
21 Claims. (Cl. 250-83.6)
This invention relates to geophysical prospect- '
ing and more particularly to well logging by the
measurement of gamma rays or other radiations
at various depths in drill holes or the like.
It has already been found advantageous to
lower various types of measuring equipment into
wells or other openings in the earth and to make
a series of measurements therein that will provide
tained has proven very valuable as an indication
of the nature of surrounding geological forma
tions.
Despite the successful measurement of gamma
radiations, many difficulties have been encoun
tered with the equipment originally proposed for
the purpose. The original instruments were not
as sensitive as was desired. The capsules in
a parameter of something related to the structure
which they were enclosed were not strong enough
surrounding the well bore, in correlation with m, to withstand the terii'llc pressures encountered at
depth. These parameters are commonly referred
great depths, could not be sealed tightly enough
to as “well logs.” They are generally formed by
to prevent leakage, and were too large to be in
making a continuous series of measurements of
serted in a hole of small diameter. The detector
some kind in a Well bore over a continuous range
and other equipment lowered into the well were
of depths and plotting the measurements graphi 15 not sturdy enough to withstand the mechanical
cally so as to give a continuous curve of depth
versus the magnitude of the characteristic being
shocks received in normal field use.
The power
supply was not steady enough. The measure
ments
could not be accurately transmitted to the
'I'here are many examples of the making of this
surface. The instrument could not readily he
kind of measurements, probably the most common 20 assembled and disassembled so that building and
being the measurement of the resistivity of the
repairing it were long tedious processes.
strata at various depths. The temperature, nat
The purpose of the present invention is to elim
ural potentials of the strata and many other char
inate as many as possible of the objectionable
acteristics have also been measured in a similar
features from the equipment originally proposed
manner. Recently, it has been found that radio 25 for radiation well logging and to provide an in- "
active radiations emanating from the strata, for
strument to he lowered into a well, and surface
example, gamma rays can be measured and corre
equipment to go with it, which will be highly
lated with depth in a similar manner and that
sensitive,
be very accurate, be so sturdy that it
there are many advantages to measuring them as
will not be injured by any of the things that may
indications of the nature of adjacent geological 30 normally happen in the held use of the instru
formations.
ment and that will be -so constructed that the
Gamma rays, neutrons and the like penetrate
component parts may be readily removed for
metal with relatively little difiiculty and hence
repair or replacement.
measurements of theseradiations may be made
The ionization chamber which receives the ra«even in a well that has already been lined with a .
diations
from the surrounding strata has, to this
steel casing and with an instrument which itself
end, been arranged to occupy the full cross-sec
is enclosed in a steel capsule. Furthermore, al
tion of the instrument. It comprises a steel shell
'most all natural substances are radioactive and
which at once forms a. portion of the outer casing
the extent of their radioactivity is a good index of
the instrument and at the same time, the outer
their nature. Still further, not only the intensity 40 of
wall of the ionization chamber. Within this
but also the nature of the radiations are different
shell and insulated therefrom is an outer cylin
when they come from different formations and
drical electrode and an inner rod-like electrode.
determinations can be made of the differences in
An electrical connection from each is carried
types of radiation as well as the differences in
through an end wall of the chamber by an insu
intensity. Then too, radiations may be artifi 45 lated
conductor very much like the ordinary auto
cially introduced into the surrounding strata by
measured.
'
a source of radiation lowered into the drill hole
and the effect or action of these radiations may be
determined.
'
Work on the detection of radiations of this type
has already passed beyond the experimental stage
and measurements have actually been made
through casing, on a commercial scale, of the
naturally emitted gamma radiations of the sur
rounding formations. The information thus ob
mobile spark plug. In fact, automobile spark
plugs have been slightly altered and used for this
purpose. The inner electrode is shock mounted
and insulated from the casing by a quartz rod
spring mounted in one end of the electrode and
by one of the spark plug like structures at the
other.
Such a structure provides an ionization
chamber of considerable volume without making
necessary a very large outside diameter for the
instrument and at the same time permits the
2
2, 349,225
reduction of leakage current so that very ñne and
at the same time very accurate measurements'
may be made. As will be seen later, the electrical
connection between the battery which applies
potential across the electrodes, the electrodes
themselves, and the casing, are such that what
little leakage there is tends to be between the
electrodes and the casing instead of between the
electrodes themselves and this 'leakage is ignored
nating current amplifier, which sends its signals
to the surface of the earth, where these signals
cause a readjustment in the current sent
through the balancing resistor. As soon as the
state of balance is reached the signal to the
surface ceases, the system is in balance and a
record of the current being sent to the bal
ancing resistor is recorded as an indication of
the gamma radiation at the particular point in
10 the well.
.
.
by the measuring circuit.
It has been found desirable to commutate the
Removably connected to the section of the cas
current sent to the surface and amplify this
ing which forms the ionization chamber there
current by an alternating current amplifier in
is at least one more section of casing of the same
outside diameter and within this section of cas
ing are positioned two more units of the instru
ment.
The first, which is- positioned directly
above the ionization chamber, is a unit which
measures the iiow of current in the ionization
chamber and sends an appropriate electrical
signal to the surface of the earth. The sec 20
ond, which is positioned above the first, contains
order to prevent the usual drift of a direct cur
rent amplifier from affecting the accuracy of
the measurement.
This has necessitated some
arrangement whereby the surface equipment can
be made to adjust the balancing current in the
proper direction, since an unbalance in either
direction will cause an alternating current signal
to be sent to the surface. To this end a second
alternating current signal is sent to the surface
from the operating circuit of the capacitative
commutator and the phase relation between this
trodes of the ionization chamber, or, alternative 25 second current and the signal current are there
used to determine the direction in which the
ly, this source of 4 power may be contained in a
balancing current must be` adjusted in order
separate section of the instrument casing re
to balance the circuit.
_
movably attached below the ionization chamber.
As can be seen from the foregoing descrip
In order to expedite the removal of the two
tion, the arrangement so far described necessi
units of the instrument which are placed above
tates the sending to the surface of two different
the ionization chamber, the lower of these two
alternating currents and the return to the in
units is formed to extend from the ionization
strument of at least one direct current for bal
chamber to a point adjacent the top of the sec
ancing purposes. Multi-conductor cables how
tion of casing within which it is contained. The
upper portion of this unit, however, is merely 35 ever are both expensive and diñicult to maintain
and an arrangement has therefore been devised
a hollow shell in which the second or upper of
by which the two alternating currents may
the two units may be positioned. Means are then
be made to have different frequencies, trans
provided for sealing the upper end of the casing
mitted over the same cable, and at the same time
against the entrance of ñuids from the surround
ing well bore, connecting the casing to a sup 40 not interfere with the transmission of the di
rect current over the same cable. This is ac
porting cable, and making electrical connections
complished by a proper arrangement of fre
to the conductor inside this cable so that current
quencies and filtering circuits. ' The signal cur
may be transmitted to and from the surface
rent is ordinarily caused to have'a frequency of
through a single conductor inside of the cable.
around 'I4 cycles, the phasing current, a. fre
In order that the ionization chamber may be
quency of around 592 cycles and the balancing
as sensitive and as accurate in its indications
current is substantially direct current.
as possible, and in order to minimize the errors
a source of electrical power for operating the
measuring circuit. It may also contain a source
of power for applying voltage across the elec
that may occur in the transmission of the indi
If batteries are used as the entire source of
‘ power within the instrument, then it is not nec
cating signals to the surface of the earth a
“null” type of measuring circuit has been de 50 essary to conduct any other current over the
single conductor cable that supports the instru
vised. Accordingly, the outer electrode of the
ment, but when it is desired to supply power from
ionization chamber has been connected through ‘
the surface of the earth to operate -either the
a battery or other source of voltage to the casing
measuring circuit, the ionization chamber or
and the inner electrode has been connected
through a relatively high resistance resistor also 55 both then a current which is of still a different
frequency may be sent down into the well over
to the casing. By connecting the outer electrode
the same cable and separated in the measuring
through the battery to the casing the major part
instrument from the other currents by appro
_of any leakage that occurs will be between the
priate ñlters. It has been found that a current
outer electrode and the casing and this will not
aiïect the current flowing through the resistor. 60 having a frequency of 5 kilocycles is satisfactory
for this purpose.
Originally, the voltage drop across the resistor
When batteries are used to supply the power to
was used, directly, to govern an amplifier, but
the measuring circuit they are contained in the
this has been changed, a second resistor has
been inserted and an arrangement made so that
upper of the two units above the ionization cham
current from apparatus on the surface of the 65 ber and connected through a plug and socket ar
earth can pass through this second «resistor to
rangement to the unit which contains the meas-
make the potential drop across it equal to that
across the first resistor when the system is in
uring circuit. The measuring circuit is similarly
connected by a plug and socket arrangement to
f a state of balance, so that there is then no volt
the ionization chamber. It has been found par
age across the two resistors when placed in series, 70 ticularly _desirable in case batteries are used to
as they are in the present arrangement.
place in the battery compartment one or more
In order to make this system an operative
switches which are gravity actuated so that when
null system, any overall potential developed
the unit is removed from the well and laid on its(
across the twc resistors is used to operate,
side thel batteries will be disconnected and the
through a canacitative commutator. an alter
2,349,225
circuit th'freby‘u‘stopped .from opera’
. Figure
~tion.
f
'
^
the signal current from thel>l measuring instru
Figure 12 isla wiring diagram of the surface
inthe upper unit of the measuring instrument
so thatthe power from- the-surface', is properly
panel which selects and ampliñes the' phasing
separated from the other currents in the support
ing, cable, rectified, filtered as necessary, and the
current fromV the measuring instrument; and i
Figure' 13 is a wiring diagram of the surface
panel which comparesthejmeasuring current and
the phasing current andadjusts the balancing
current and operates the recorder.
Así specifically illustrated in Figures 1 and 2
the measuring instrument '2Q comprises an elon- `
proper voltages applied-to the various parts of
the measuring circuit. Such a powerpack ar
rangement maybe arranged .to supply voltage
across the ionization chamber as well as 'to the
measuring circuit but ordinarily this will not be
found to be desirable and the ionization chamber
will be supplied withvoltage by a separate bat
'
'
11 is 'a wiringI diagram vof the panel of
vsurface equipment which _selects and ampliñes
‘
" - When power isto. be sent from thesurface, ap
propriate nlters and rectiil'ers are contained with
tery.v
3
,
gated steel tube made up of several sections. i
Starting with the section 2| vwhich forms at once
, lthe outside wall of the instrument. and _the outer
.
At the surface of the earth the supporting cable
for the measuring instrument passes over a wheel
which is connected through either an electrical
for a mechanicall transmission system to a recorder 20
wall of the ionization chamber there is attached
to the lower end of this section a second section
22 of the same diameter, which section is sealed
at its lower end and contains batteries which ap
vso that the recorder tape moves as ythe measur
ply potential across the electrodes of the ioniza
tion chamber. Above the ionization chamber sec
ing instrument moves up anddown in the well.
The supporting cable is then wound on to a cable
tion l2| is a third section 23,v also of .the same
drum through which connections'are made byv
diameter as the ionization chamber and this sec
slip rings and brushes from the center conduc 25 tion encloses the measuring circuit unit and the
power supply unit of the device. Above the third
tor and the cable itself to a series of thre'e panels
section‘23 are two short sections 24 and 25, each
interconnected so that oneV panel detects and am
of the same diameter as the remainder of the
plifiés the signal current, another detects and
casing, and above these is a member 25 specially
ampliñes the phasing current and the third com
pares the resultant currents and properly ad-v 30 constructed to receive and hold the lower end of
a supportingI cable 21.
justs the balancing direct current sent back to
On the surface of the earth is positioned a
the measuring instrument, at the same time actu
measuring wheel 28 over which the cable 2l
ating the recorder so that it records the amount
passes to a cable drum 29 driven by a source of
of balancing current sent back to the well. In
power not shown to raise and lower the instru
addition, a source of power may be connected
ment in the well. Connections inside of the cable
into the surface circuit to supply power to the
drum 29 carry the currents from the cable 2l
instrument in the well. This of course is used
and the conductor within it to slip rings 30 and
only in case a power pack is used in the well
3| from which they are picked up by brushes 32
vinstead of batteries.
’
Numerous additional details of the device of 40 and 33 ‘and carried to the amplifying and con
this invention `and numerous advantages not ‘ trolling panels 34, 35 and 36. The amplifying
panel 34 selects and ampliñes the incoming sig~
heretofore mentioned will be evident from the
’ nal which indicates the state of balanceof the
following detailed description of this device and
from the appended drawings. It is toy be under A45 measuring circuit in the well, the amplifying
panel 35 selects and ampliiies the phasing cur
stood, however, that whilethe device illustrated
rent from the well and the control panel 36 com
in the drawings is the preferred form and many`
pares the amplified signal current and the am~
of its details form important parts of this inven
pliiied phasing current, makes the necessary cor
tion, that the invention is not limited to the com- l
bination of all of the parts shown in the ap 50 rection to the balancing current being sent back
to the well and actuatesa recorder 3l in ac
pended drawings or described in the following
cordance therewith. The recorder 3l has its
detailed description, or even to the exact embodi
tape driven by a mechanical or electrical trans
ment of any one of the many details.
`
mission system 38 from the measuring wheel 28.
In the` drawings:
.
Thus a continuous log is made of the garnîna
Figure 1 is an elevation, partly in secti‘on show
radiations encountered versus the depth. »A
ing the measuring instrument as a Whole, in the
source 39 of 5 kilocycle power may be connected
position in which it will normally operate;
into the cable through the brushes 32 and 33 as
Figure 2 is a diagrammatic illustration of the
shown in dotted lines in Figure 2.
l
` surface equipment which together with the in
I strument of Figure 1 forms a complete appa
. Considering now Figures 3, 4, 5 and 6 to ob
60 tain a more detailed understanding of the me
ratus;
'
,
chanical structure of the measuring device we
Figures 3, 4 and _5 are sectional elevational
find that the ionization chamber is formed by
Vviews on a much larger scale than Figure 1, illus
Athe steel shell 2| which is closed at its opposite
` _trating, when taken togethen-the more detailed
ends by metal discs 40 and 4|, preferably of steel
construction of the measuring instrument;
and welded into place by Welds 42 and 43 respec
Figure 6 is a sectional view of the measuring in
strument taken on line 6--6> of Figure 4;
tively.
'
Figure ’Z is a circuit diagram of the measuring
circuit of the instrument;
»
Figure 8 is an elevational view partly in section
of the battery unit of the measuring instrument;
` ' .Figureß is a wiring diagram of the same `bat
tex-y unit;
"
Figure 10 is a wiring diagram of a power sup- -
ply unit for the 'measuring instrument;
V
Within the chamber so formed is positioned an-
outer electrode 44 insulated from the wall of the
chamber by a good insulating material ‘45. It
has been found that glass wool fabric impreg
nated with a synthetic' resin is very'satisfactory
for this purpose.l
'
.
In the center of the ionization chamber a sec
ond electrode _.46 is positioned. 'This electrode is
tubular in` shape and supported at its top end
4
8,849,225
from a sparkplug-like connection 41 which ex
tends through the top 4D of the ionization cham
‘ a disc-shaped member 66 welded lntofplaceby
` a weld t5.
ber.` ’I'his connector 'can be described as an ordi
` In order thatlthe batteries may be expedient-.ly
nary automobile sparkplug with the outer point`
removed and the inner point lengthened and
placed in this compartment and the proper con»
necti'ons made, a rack 66 is` provided. This rack
threaded.' The connector as a whole is threaded
includes’a flanged positioning plate 6l so formed
as to í’lt against the bottom plate of the ioniza
tion chamber and around the sparkplug-like con
into the top £10 ofthe ionization chamber in the
same manner that it would be threaded into:
the head ofç an automobile engine and is pro
nectortwo
58 strap-like
and the valve
members
@2. From
tu which
this carry
plate be
ex_«vided with a gasket ¿lâ-which prevents leakage of _ Y `tend
gas around it. At the lower threaded .end of the
central conductor it carries a plug 49 threaded
thereon and locked into position by a locknut 5B.
"I'he upper end of the tubular central electrode
¿it of the ionization chamber fits over this plug
¿la and is attached thereto either by reason of
tween'them a pair of cross plates 69 and l!) one
_ of which is to be above the batteries and the other
of which is yto be below the batteries when they?
are placed'in~ position. The batteries, shown in
dotted lines in Figure 5, are vthen placed in posi
:tion between the/straps @t and between lthe plates
the tightness oi’ its iit or by solder, brazing, weld
ing, screw threads or any other expedient means.
The lower end of the tubular central electrode f
59 and l@ and simplytied- or taped into position.
y'I‘he upper plate 59 is provided with openings
'il and 'i2 through which connections from the
¿i6 is supported by a cup-like structure 5l which
forms a part of the lower end member lll of the
n batteries may/passl and as can be seen these open
ionization chamber. In this cup member 5l ‘is
received the lower end of a quartz rod 52 vex
' wires ï will not short circuit.
ings are surrounded by insulation so that the
tending upwardly into the center of the tubular
nector'äii is shown in dotted lines as isalso a con
electrode 4S. Inside of the tubular electrode the A
nector from the negative side of the batteries to
quartz rod is slidably received in a guide member
53 heldin position in the tubular electrode by a
machine screw 5d.
v a lug T13 on the ionization chamber casing.
The'upper end of the quartz l »
rod which passes on' through the guide member
is received in a slider 55 which is free to slide
up and down in the tubular electrode ¿i6 but is
The connection
from the ~positive end of the battery to the con
A
spring pressure plate lll is also provided, which
plate is mounted on the lower end of a battery
holding frame and arranged to press against the
30 lower end of the casing for the battery compart
X'ment when that casing is in place. Thus it pre
vents the battery supporting structure from vi
brating or shaking when the device is assembled.
Above the ionization chamber as has been said,
yieldably urged downward by> a spring 56 which
presses at its lower end against the slider 55
and at its upper end against a block 5l ñxed
within the tubular electrode. Thus the central 35 is the third section of steel tubing 23 which en
electrode is well insulated from the casingfand
-closes the measuring and power supply units.
the outer `electrode and at/the same time so
For the purpose of attaching this section of tub-A g
mounted that it is not likely to be broken loose
ing, the side walls of the ionization chamber are
from its support by shocks incident to the han
arranged;- as at the bottom of the ionization»
dling or use of the instrument.
.
chamber, to extend some distance beyond the top
The outerelectrode ¿3G is supported by the
closure member dll of the ionization chamber. A
insulating material which insulates it from the
short length of tubing l5 a little larger in diam
case and is connected outside the chamber
~ eter than the insidediameter of the ionization
through a second sparkplug-like connector ‘58,
chamber case is then machined so that its lower
mounted in the bottom closure member ¿il of the u end will slip into the ionization chamber case and
ionization chamber and provided with a gasket i
welded into place therein by spot welds i6.
59 in much the same manner as the connector
l The upper end of this short piece of _tubing
for the central electrode. This connector, like
carries screw threads ‘ll and the lower end of the
the one for the central electrode, has no outer
next higher piece of tubing 23 carries internal
point and has an elongated inner point @G which
screw threads at its lower end so that it may bek
makes contact with the electrode in the ioniza
screwed tightly in place atop the ionization cham
tion chamber. It is further provided with a hel
ber. Within the lower end of this upper piece of
ical spring lìl which is attached at its lower end
tubing 23 is` positioned an annular member ‘i8
to the central contact point El) and presses at
shaped to fit closely over the short piece of tubing
its upper end against the outer electrode ad of 55 'i5 and having a conical section 'i9 on its upper
the ionization chamber, to insure good contact.
' face so as to position the measuring unit that is to
A valve 62 is also provided in the bottom member '
be placed therein. Furthermore, the annular
läi of the ionization- chamber so that the ioniza
tion chamber may be ñlled with the'appropriate
gas at the appropriate pressure. Argon at 100i)
lbs. per sq. in. has' been found very satisfactory
-ior use in the ionization chamber.
'The side walls 2| of the ionization chamber
' member 78 has a pair of holes il@
“il
tudinally in it to receive a pair of studs from the
measuring unit so as to fix the position of' the
measuring unit still further.
The measuring unit, designated generally as
8|, comprises a long cast metal frame 82 which
extend somewhat below the bottom closure mem- `passes lengthwise alon one side of the measuring
ber 4| and are provided internally with'screw 65 unit and includes a su stantially round plate at
threads so that another section of the instru
each end. At the lower end two positioning studs
ment may be attached. This section 22 is a con
83 are mounted and arranged so that they will
' tainer for the> batteries vthat ~ apply potential
enter the holes 8B in the annular plate 'i8 when
across the electrodes of the ionization cham
the measuring unit is lowered into position. Sur
ber. It consists of a relatively short length of
rounding the frame 82 is a metal cylinder d@ f
steel tubing of the same outside diameter as the
which encloses the frame and the parts of the
ionization chamber. ~ '_I‘he top end of this tubing
measuring circuit. To simplify the drawings and
is cut away and externally threaded at 63 to
explanation the parts of the measuring circuit
iit the threads `in the lower andl oij the ioniza
tion chamber.v It `is closed at the bottom by
have not been shown, although the circuit dia
gram for these parts'will be found in Figure 7.
_
.
.
_
o
_
Y
-,
'5
»2,349,925
, Il_'ixedto theoutside of the cylindrical cover u is
la soft positioning ring Il which serves to assist
' . withoil'through an _opening |00v and closed by a
set screw. The anchoring member |00 is shaped
Afurther in-»positionin'g the measuring unit in the .
at ‘its .upper end so ` asV to present teeth |09
outer casing and preventing vibration of the unit- '
whichmay bev grasped by va ñshing tool should it
within-the case.
become impossible to remove the measuring in
,
4
.
_
.
.
Connection is made between the central elec
’ strument from the 'well byordinary means.
. Reference will now be had to Figures '7 and 9
- trode'oi .the ionization >chamber and the measur~
‘ ing circuit through the connector 4_1, already de
for the purpose of describing the measuring >and
' scribed, and through a second connector 0l which _i0 power supplycircuits. - According to these iig
ismounted in an insuiator a1v 1n the frame o_f the
ures the central electrode- ofthe ionization cham
' measuring unit. 1' The upper end o! the connector
ber* _is connected through contact H0 and resis
41 is arranged as a plug and the lower end of the
tors III and H2 to ground. _Thus with the outer'
_
connector 80 as a socket so that when the meas- '
Felectrode of _the ionization chamber connected
" ûring unit is slipped into place in the casing the
through a battery or other source oi power to
plug and socket* will automatically fit together L15 ground a complete circuit is_had_and the flow
and give the desired connection.' Preferably, the
of current in the circuit depends upon the gamma
_ plug and socket connection are such that the
radiation reaching the ionization chamber'and
" contacts arel spring pressed against each other to
thus changing its resistance.
_
_’insure a ñrm, low resistance connection at‘- all
One plate H3 oi a capacitative commutator
times.
20 H4 is connected to this circuit at a >point'be
At the top end ofthe measuring unit proper a
tween the two resistors and hence _as the cur
Y small annulus'ßßeis ailixed to the frame 82 and a ' rent flow‘in the circuit' varies the potential of
thatplate relative to*- ground potential will vary
'. upward
sleeve 90i'orfa
is amxed
suihcient
toïthis>
distance
annulus
to'and
enclose
extends
the »
as the voltage drop across the resistance H2
power unit. A resilient positioning ring 9| is
lpreferably attachedto the outside of this ring
varies. K'I’hefother plateA H5 of the‘commuta
tor is connected to ground through 'a condenser
H8 to rid it of any" currents of unwanted fre
near its lower end so as to still further aid in posi
' tioning the measuring unit in theouter casing.
'quenciesvand its potential is controlled from the .
The power unit is enclosed in a vcylindrical case
I'92 of‘somewhat smaller diameter than the inside
of the sleeve 90 and is rlowered into the sleeve v90
surface of the earth so that it may be brought
30 to the same potential as _the ñrst mentioned plate
either before or ener the measuring unit is placed ’
in the outer casing.- It carries at its lower end a
plug connection 93 which cooperates with a- A
i
socket connection 94 in the upper end_.of the
measuring 'unit proper. vThe details oi’this/plug
andsocket connection have been omitted to
simplify the d?awinss.-
_
.
\Above the top end of the power
H3. The iirstlplate ||3,is also connected to the
vcontrol -grld of a thermionic amplifying tube H1
through a condenser. H8 and a resistor VH9 is
placed between the grid- of the vacuum tube.
and the ground so,y that no permanent charge will
Aremain oir/the grid. The capacity of the com
mutator H4 is periodically varied at a constant
lfrequency by _means 'to be hereafter described.
l
unit andA _ the .
With> the arrangement so far described and.
shell 00 which surrounds it and extends a little
40 with a constant or'slowly changing ilow of cur
above it, the outer“ casing 23 is internally
rent lin the ionization lchamber circuit and with
threaded. fIn order to hold the powereand meas
the two commutator plates H3 and H5 at the
uring units iirrnly in place, a double tapered an
same Vpotential thererw'llldbe nol potential drop
l,nume as is e‘rre'nged to at just within the sur- ~ across the commutatorand hence its change in
`L sounding-sleeve 90 and press downwardly and -45 capacity will produce no potential change across
inwardly aî'gain'st the. top of the power unit 92.
vthe grid of the‘ampliñer tube. 'I'he constant or _
_ This annulus is heldin place by a second annular
. ring 9F _which is tapered to press outwardly
_
slowly changing potential across the/resistor H2
will _n_ot aiîect theA grid of the amplifying tube
against theñrst ring and threaded sc» that it can
ibecause the resistor H9 will allow current to
be screwed down inside the outer casing. An ex-- 50 pass suilìciently rapidly to keep the grid of the
ternally threaded lock nut 01 secures the second ` ’tube aia-ground potential. If, however, the plate
annulus iñ place.
l
l
'
H5 of the commutator is 'not kept at the same
The next problem is the sealing of the' top iii',
of'
potentialV as -the plate H 3 then the variation in
the instrument and the anchoring of the support
capacitylof the condenser-commutator will vary
ing'cable therein.- This is accomplished byscrew
thepotential on` the plate | 13 and since this
ing la' double male plug 90 into the top of the‘
variation will take place at the frequency of
upper casing section 23, covering this with a
variation of oscillation of the commutator it will
female-male plug 89 and screwing an anchoring - e be suñiciently'rapid to cause an alternating cur
member |00 onto the top ofthe male-female plug. >
rent to be impressed on the grid of the tube H1
The electrical connection is carried through> the
so that asignal will be sent out from that tube.y
double male plug 98 and through the-male-Temale
The variation of capacityof the ycondenser
oommutator is produced by causing one of the
plug 99 by sparkplug-like connectors I0) and |02
respectively. The connection is made from the
power supply unit to the lower of these by a flex-_
ible connection |03 and between the two con
plates _H3 vto. act as an armature'in a buzzer
_ type of_ circuit comprising a solenoid |20, _a car-l
65 bon button |2| and batteries |24 and |25 both in `
nectors themselves by a plate |04 'iixed tothe top ' '
`of the lower one and a helical spring |05 flxed to
the bottom of the upper one and arranged to
. press against the plate.<
The internal conductor
from the supporting cable, which is designated
by the numeral |06 is connected directly tothe
top of the connector |02.
The strands _of the cable’ 21 are spread within `
the anchoring member |00 and imbedded in lead ’
|01. » The anchoring mcmber‘llll is then filled
_the power pack, all connected in series. When
¿the _carbon button is compressed by motion of
'commutator plate H3 away from the solenoid
- |20 the current from' the battery increases, thus
..01 _tending
to-return the movable plate H3 to its
former position. ‘ As the plate returns the pres
sure on the carbon- button is reduced thereby
_ reducing the current and~ lessening the pull of
the _' solenoid on4 the moving plate.
This in
'crease and decrease of current,- with attendant '
_' 9,349,231: I
‘ moties of. -th'eeblede ne is repeated eyeiieaily at
amplification through a circuitcompr'ising a re
6
l
'
'
`
\
v
.
a rate vdetermined largely by'the mass and com
sistor Mi, a condenser |62- and a resistancey |43,
„pliance of the moving blade which is adjusted i .to ground.' "I'he control grid of the next ampli
to operate at about, 74 lcycles per second. >
fying tube IIS’ is connected to this circuit be
>So thatv the circuit _may-'be readily followed "tween the condenser |62 and the second resistor
on the drawing- the plug and/socket connections _ ' |43'. ’I'he source of phasing current is'connected
„into'this circuit through a condenser. IL. at a~_ _
j point between the first resistor'ltl andthe con
bered I to 8 to correspond.` Thus' it
be
seen that connections from the solenoid pass yto
. dense‘r |42. Thus, both the phasing current and Y
the power> supply >unit through connections 6_
and 1, and from connection 8. to ground through
the primary of transformer |21 which will be'
the signal current are placed on the control grid
‘of amplifier tube | i8'.
. '_The amplifying tube. H8 is of peculiar con
hereafter described in more detail, in series with -' - >struction being .in eii‘ect- three tube units com
the carbon\button `|2|. The' condenser |26 >is
also .connected from connection number 8 to
ground. Between connection- .number 'ifand~
ground are connected 'the batteries,"infami>
|25 in lseries with which is the gravity oper
ated switch |28 which stops the operation of
the device when the' measuring instrument is 20
removed from the well and -laid on its side. ^ It
' will be `seen that direct jcurrentfromv the bat->-`>
bined in one. The first of these three tube units,
the operation of which iscontrolled by the con
‘trol grid |65, just _mentionedfis'a three element
tube comprising only a cathode, the control grid
M5 and a plate m6. The second of these tube
kunits is a diode rectifier comprising only the
same cathode and a plate lli/l. The third of these'
-tube units is a ñveelementtube comprising the
same cathode, a controlegrid Itâ, a screen grid l
tery ñows through the switch |23, the~ primary
|49 and a suppressor grid läd, which is connected
directly to the cathode, anda plate |5i. ‘
and the solenoid |29.' The condenser'iZi serves 25 .The plate |66 of the triode amplifier is sup
, of the transformer |21, the carbon button ‘|2i
to broadly tune thesolenoid winding to approxi»
plied with voltage from the plug connection 3 in
i which is connected'directlyacross the carbon
the same _manner as the plate of the first ampli
iler, ill through a resistor |52 and is connected
through a condenser |53 to the control grid lds
mately'74 cycles persecond, and condenser |22
button-serves to bypass any unwanted high fre
`guencycurrents 'generated by m'otion of theLcar
. bonbutton. Thus it willibe seen that the con
k,denser plate `i I3 will -be continuously oscillated
and that a surge of current will pass. through
-the primary of the transformer |21 at each oscil
» lation.
The phasing current previously men,
tioned is derived by use of this transformer.
30 `xof the7 pentode amplifier so that the output of
the triode amplifier of the tube H8' is
pressed
’ . on the controlgrid ofthe pentode amplifier of ,
_the same tube. ,- Unwanted frequencies are car
ried» olf to ground through ak condenser. |515,- also
- connected to the plate |556 oi’v thetriode.
‘
The control grid ‘|68 of the pentode amplifier
` As can be seen by an inspection of `Figures 9
'is connected through'aresistor |563 to the plug
and 7 current from the central conductor of the. Í connection 8 which carries through toa pair of
supporting cable _reaches “the> measuring circuit ' batteries |55 connectedin'series in thei'power
thrcugh the number d connection on the plug and
unit.v The' positive end of these batteries is con- ‘
socket which’connects the measuring instrument I, f Anected to ground. This furnishes the proper neg-` '
andthe power, supply.' The‘direct current Icoin-y~ -atlve bias for the control grid of thepent'ode.
ponent of the current in-this conductor is per
The Plate iëi of “the pentode 'is connected
mitted to pass to ground through the-secondary ' -through the primaryof a transformer |58 td
of the transformer- |55 and resistor |29 connected
the plug" connection S so that it obtains its volt-f
in s_eries between it and vthe ground near the
age in the-^same manner asdo the plates of the
right hand end of Figure 7. The potential de»
triode and the first pentode ill. The screen
veloped across this resistords applied by con
grid lëdof the pentode contained in the com
,_ ¿nection I_sûleadingthrough a resistor itli to the
pound'tube H8' is connecteddirectiy .to the plug
_ fixed plate ill of the commutator iis. Pref-= 50
lerabiy only asmall resistance is used so that
connection 3.
‘
,
The secondaryv ofthe transformer |56 `is con
relatively large current may flow'from the ap
nected across the resistor |28 already mentioned
paratus on the surface of the earth.
,and this means that one?side of the secondary
The-ampliñer,tube /H‘ifhas- its suppressor grid
is connected tothe conductor that leads .to the
_j directly connected to its cathode and the cathode 55 surface through the plug connection ¿l landY thel
V.is‘heated by being connected through a resistor
other side of the secondary is 'connected to
to ground and on the other side through the ter»
ground'through'theresistance |29. Thus ampli
, minal | of the plug and socket arrangement to
the power pack. Inì the powerpack the termi~
nal | is connected 'through a gravity cut-olf
switch |32 `to a battery |33 the other side of
which is grounded.- 'The screen grid of the tube
||1 is connected- to ground through-a condenser
|36 and supplied'with voltage’through resistors
e i3d and |36, 'and plug connection 3 from a hat@
_ tery |31 in the power-pack. Voltage for the plate
of the tube ||1 is taken from a point between
resistors |35 and |36 through 'a resistor |38 and
ñed currents representing both the signals from.
the ionization chamber and the phasing current
are sent to the surface of the earth.
. V
' TheV phasing'current originates in the trans
former |27 which, as has already been explained,
hasits primary connected in series with the car
bon vbutton |2| and which therefore receives a
surge of current foreach oscillation of the mov
able plate Htl of the commutator lid. The sec
ondary of the transformer |27 is connected in a
seriescirciiit starting at the grounded cathode '
alterating current is by-passed to ground from. ` of the compound tube Ha', continuing through
the samek point through a condenser |39. The 70 the plate of ydiode lill included in that tube, y*
plate of the vacuum tube |¿|'| is also directly con- .
nected to ground throughs Lcondenser |50 of
such _a :size .thatit will bypass currents of un»
wantedfrequencies.-
1r
. r The signal from tube
"
'
' lthrough the parallell combination of the resistor
|51 and the condenserv |59, through the second
‘ary of the transformer i2? and through the par- ’
alici resonant inductance |52 and condenser |63.
combination of valuesof theresistor |57 »
-'| n is rasen for 'further ze - The
_
2,349,926
an’d‘the condenser ‘H9-«are so 'chosen that the! _ and a condenser |16 is also connected 'between
y diode rectifier‘l41 passes a short current pulse " the plug terminal 8 and ground to by-pass Íun
¿ist the penser-‘each cycle -of the vous@ induced _ , wanted' high frequency- current.
in the secondary‘of the transformer |21. by the.A third secondary |11 of the transformer |64
current .iiowing `in/ its primary. -'I'he current
supplies current across a pair lof bridges eachl
. pulses pass from the .diode through»thefresonant> comprising four chemical rectifiersar'ranged to
combination of >inductanc'eA |62; and condenser' vlmake a full-wave rectifier, usually of the “sele
|88'where they excite a’damped oscillatorywave j .' _nium”rv_ariety. /The first ofy these 'bridges |18'
train whosevfundamental period is determined ,_ ‘is connected directly across the secondary |11
by the` resonant -frequency of these> circuit ele
while the second of >these bridges' |19 isîconá
ments. Since a pulse of currentfrrom the diodev ¿",nected vacross the’secondary throughÍ I‘a pair of
>‘passes through ’ this-Í resonant combination -for.'
'_condensersr |80 and |,8|, one of the condensers
each oscillation of the movable plate! I8., which .v Í -being placed in each connection to the bridge. »
oscillates at a frequencyof ’Mioycles per lsecond
' The connections from the secondary of the trans
a- series of'damped waves, recurring at a rate
` of 'I4 timesyper second ‘is produced.
-former to each /of> the bridges is made at opposite
The reso- `
I- corners `and one of the remaining corners of each
nant frequency of> the inductance |62 and the '
Í condenser |68 is chosen to favor thefeighth har--v
- ofthe bridges isv grounded.
monic ofthe '14 cycle pulses vand therefore a-se
Vries of damped wave trains having afperiod of
‘592ocycles, repeating ata4 rate of 74 per second
is produced.h These wave trainsl are- thus the
equivalent of a 4signal of 592 cycl'esper second,
modulatedí'in amplitude 'at a rate of 74 cycles-y>`
per second, and are fed into the amplifier along 2s.
I
with signal voltage from the tube _I1"w»hich is
of '74 cycles`frequency. Since,- the pulses of cur
rent in lthe diode’determine the start of`each
' wave train the phase relation of the 74 cycle> en
. yvelope of this l'current bears a fixed time rela.
tionship’to the movements of the commutator,
. the vphase relation :between the 'I4 cycle envelope
of this current and the signal current c`an.be
later compared to determine the directionl
' of un.
This leaves but one '
vremaining corner oneach bridge. lThe remain
\. ing corner on the first bridge |18 is connected
20 directly 'to' the plug connection | which supplies
`
current to the filaments of the amplifier tubes.
It is also connected [to ground through a condenser |82 so asxto by-pass any unwanted high
frequency curren .
„
»
l
The remaining .corner of the second bridge |19
is connected through a pair of resistances |83
and |84,l which are in' series, to plug connection
8 which supplies grid bias to the controll grid of
the pentode-portion of the second amplifier tube. f
so
High.` frequency currents are discharged to
`- ground from this circuit by‘a pair >of'condensers
|85 and |86; the first of which is connected from
` a point between the two resistors |83 and |84 to‘
'g'36 ground, the second' of which is connected from
balance-of the signal `current circuit.`
apoint beyond the second resistor |84 to ground.
A stabilizing resistor |81 isjalso connected from
When batteries are used as asource . of power `
a point beyond the second resistor |84 to ground.
Another, connection` from the last remaining
corner of the bridge |19> leads 4through a resistor Í
ply compartment and> through, the plug connec
.tion 4 in the measuringv circuit. There is a slight 40 |88- to the plug connection 1 'which supplies op~
erating current to the commutator circuit. This
difference, however, as can be ‘seen in' Figure 10, v
circuit is also grounded through a condenserA I 89
when power is supplied to'l the unit from the sur-'
supply, the lead from the center of the support
ing cable passes directly through the power sup->
at a point beyond the resistor |88.
face of the earth. ¢ In the latter case the lead
I
[At' the surface of the earth, the` connection
from the center of the supporting .cable passes .
from the conductor inside the supporting cable
is carried to each of'the panels 34, 35 and 36
and’also to the source of power.v supply 39 if one
is used, and the connection vfrom the cable itself,
through a transformer |64 in the power unit,
then through 'al filterA |65, and is connected to
ground through condenser |66 before it passes
through the‘plug connection 4 to the measuring
circuit. Power is taken through the transformer
|64 for the operation ofcthe power pack and
the iiiter |65, and the condenser |66 prevent the
that is the outside sheath of the cable, is ground
ed to each one of these units.
In the unit 34 which comprises the circuit for
passage `of current' of the power frequency into
the measuring circuit. The filter |65 comprises
' selecting and amplifying the signal` current, the
a ground connection for the. line through a choke
porting 'cable and the ground connection are led
through a condenser |90 and a> filterI circuit to
connection from the .condenser inside the sup
|61 and acondense? |68 connected in series and
the primary of a> transformer ISI, The filter circuit consists of a choke coil |92 placed in series
also includes a choke, |69 and a condenser |10
connected in parallel in the line.
From the >transformer |64 ,power is taken
through a full wave thermionic rectifier to sup
ply the plate and‘screen voltages and through
" dry-disc rectiiiers, preferably .of thef‘selenium”
variety to supply the' lower voltages required for
filaments and grid biases.
,
v
For this purpose the transformer has one cen
ter tap secondary |1| whichserves to heat the'
with the incoming line, a condenser |93 across
this choke coil 'and two additional condensers
60 Y|94 and |95 between the incoming line and the
ground connection,fone before and one- after the
incoming line has passed through the choke coil.
The various capacities and‘inductance are so
proportioned that they tend to exclude direct
_current and currents of frequencies other than
filament of` a full wave rectifier tube |12 and a
second center tap winding |13 which servesl toÍ
supply voltage to the plates and grids- 'of that
that of the signal current.
The output ofrthe transformer |9| is connected
to a double pole double throw switching arrange
ment |96 which serves to reverse the phase of the
same tube. The centertap of the second wind
~ ing |13 is Agrounded and the center tap of the 70 incoming current. The phase is then further ad
first winding |1| is connected through a ballast
resistor I14‘to the plugï terminal 3 which sup~
plies the vscreen grid and -plate voltages to the
measuring circuit. stabilizing resistor |15 con
nected between the plug terminal 3v> and ground 75
justed by another network and impressed on the
control grid of a pentode ampliiier |91.
This further adjustment is accomplished by
placing a pair of resistors |98 and |99 in~ series
across ‘the reversing switch |96 and grounding
i
8
»the circuit at a point between them. A con
ing connected into the plate circuit of they pre
denser 2'00 is v-then connected between one ter
`mina] of the reversing switch and the control
>ceding tube just above the choke_coil 22| and .
the condenser 223. lh series withfthe plate of
gridbf'the‘tube |91 and/a variable resistance
- tube 22TA are two, resistors- _232 and 233 and a
20| is placed between the other terminal of the ' s ' voltage istaken for the screen grid from a point
reversing switch and the controlv grid. By ad
between these Atwo resistors and applied 'to the
screen grid circuit between the Aresistor 232 and
Justingthis variable resistance 20|` the phase.
I .of the incomingfsignal may be,_further shifted
to place it exactlyin phase with the phasing
current.
_
-'
.
A
v'I'he ampliñer'tube |91 is a pentode of the
indirectly _heated cathode type and- since the
heatery current does not enter into the elec
trical _circuit‘hereinvolved its source is not
' shown.
The cathode is grounded through a re
v sister -202 and the plate, screen and suppressor
i
-
>the condenser 22| of that circuit.
ld‘ñerltube 236,_wl_hich is of 'the> beam power type
is taken by a circuit comprising a condenser 2321
-and a resistor 255 connected inÁ series between
_ the plate of' the peptodef22î 'and'ground 'A
-condenser 235'. is also connected across the re
15'sistor`235. The fcontrol grid of this tube 232
~ is connected to al point between the condenser .
grid are all connected together and furnished
23d and the resistor 235. The beam powenplates
with power through resistors 203 and 20d and a
'
-
Voltage for the ‘operation of the next ampli-`
of the tube 232 are connected to the cathode and
the cathode grounded :through a resistor 231.
_ choke 205 al1_.connected in series between this
plate and a battery or other source >of power 222. 20 The plate of the tube 232 is connected through
“ The negative terminal oi’ this battery is grounds
the primary of a transformer 238 to the battery
or other source of'power' 206 through the choke 1
22|. The screen grid is connected -directly to`
_ ed. The voltage supply circuit is also connected f”
to'ground through" two condensers 2Q? and 298
l at opposite ends of the' resistor 20d.
/
_s the same point Without‘bèing connected‘ through
Current is'taken from the plate circuit of the 25 the primary of the transformer, The output
tube |91 through acondenser 208 and a filter 2|@
winding of' the transformer 238 is of _the split
' _to supply voltage to the control grid of a second _ type with leads from the center andboth ends
amplifier tube 2li. VThe filter 2|@ is band pass.
passing to the control unit 3%. A vmeter 239
Aiìlter passing _onlyfrequencies in the neighbor
across the-outer leads from the transformer ln
_hood of that ófrthe signal current, that is to say 30 dicates the voltage of the output circuit.
» around 74 cycles. A g'rid leak resistor 2l2 is
placed- across the outputI of this filter.
.
Referring now to Figure12 for a detailed de- f‘
, scription of the circuit that receives and ampli-`
The amplifier tube 2|| is, like the amplifier
ñes the phasing current it will be'noted that
tube |9-'|,fa pentode with an indirectly heated
>the connection f?om'thejinternal conductor of
cathode. 'I'he suppressor grid is connectedrdi-` 35 the cable and the ground connection from the
rectly to the cathode which is grounded through
outside of the cable are received' at the left~
a resistance 2|3. A_condenser 2M is s'hunted
hand edge of the drawing through a condenser
across this resistance. The screen grid is ycon
2d@ and the primary of the transformer 24|.
nected 'through a resistance 2|5and a con
The condenser serves ‘to stoptheA passage of
denser2|6 to groundy and a second condenser do direct currentthrough the transformer winding.
2H is connected directly from the yscreen grid
The core of the transformer 24| is grounded and
‘Wto the ground.;y .
l
'the secondary is connected through a illter 2,62
The plate of the pentode amplifier; 2H is sup
_which is a band pass filter passing only currents
‘
<plied with voltage through a circuit including,
ofte. `frequency in the neighborhood‘of that of
_in series, threev resistors 2l8, 2|@ and 222, and a' ¿i5 the PhaSLng Current,~ WhfCh aS»` has been Said 1S
choke coil 22|. , Currents. of_ unwanted fre
quencies are carriediofl’ to ground at three/points.'
ñbetween the resistorsV 2|@ and 222 by a. con-'f
» preferably in the neighborhood of 592 cycles.
The output` of this iìlter _is connected directly
tothecontrol grid of an'ampliñer tube 263 and
a grid _leak resistor’ 262 is vconnected between
ldenser 222,-between the last resistor“ 22@ and the
- choke 22| bya condenser 223 and between the 5" the grid and ground.
choke and the battery 206 byl acondenser22?l.
' Voltage bias for the screen grid is taken from,
I‘
a point in the plate circuit 'between the re
,
sistors 2l8 and 2|@ and fed to the screen grid _ '
circuit at a point between the resistor 2|5 and 55
_
The plate circuit is vthus
the condenser 2|6.
further grounded'through condenser 2|5 at a
point between resistors 2|8 and 2|9 so that here '
again unwanted alternating currents are discharged.
.
'
y»
Voltage for the,l operation vof the next _a'mpli
`iler
the plate and ground. The movable contact of
pentode. - The suppressor grid is connected di
rectly to the cathode which vin _turn is connect
ed to the ground through a resistor 225 and the _
plate _receives-'voltage from a suitable source of
power 226, which may/be a battery as shown in
’ the drawings.~ This power reaches _the plate
through a choke coil 2137 and resistors' 268. and
‘262 all connectedv in series._ The screen grid
l 00 receives its voltage from a point in the plate cir
_
tube 22| is taken
by a condenser‘225 and a _
potentiometer 226°conne'cted in series between
The Aamplifier' tube 263
is of the indirectly> >heated -cathode type of
cuit between -resistors 268 and 263 through a
resistor 259. VAlternating current is discharged
to ground from the screen grid through a con- -
denser 25|. _Alternating current is' also dis
the potentiometer is connected directly to the _65 Charged t0 gr'llndfrOmapOil’lÉ between resistors
control grid of this amplifier tube 422`| which -is
»268 and 259by a condenser 252. _
,
.
another pentode tubewith an indirectly heated
‘ cVoltage for the operation of the next ampli
cathode. As, in the preceding tube the sup
ñ_er, tube 255 is taken from ‘fthe plate of the-
'
pressor .grid is connected directly
to the cath
y
, tube 263 through a condenser 253 and _a po- ,
ode. The cathode is grounded` through a re- 70 tentiometer 25d connected in series to ground.
sistance 228. 'I'he screen grid » is' connected to
The'slidìng arm of the potentiometer 25d isL
ground through a condenser 229 and also ,through
connected directly to the grid of this ampliñer
a resistance 2310 and condenser v23| in series. 'Iïhe
tube
255 which' is a triode having an _indirectly ’
plate is connected to thesa'me source of volt
38e as is the plate'jofthe preceding tube by' be-` 1s heated cathode. vThe cathode is connected to
ground through a' resistor 2156 and '_a condenser
9
`2, 849, 225
panel 38 from ythe righthand end as shown in
251 is shunted across this resistor. From the
plate of this tube plate current passes through ~ _Figure 13. These `currents comprise a 'Z4 cycle
the primary of a transformer 258 and through - signal current the amplitude of which'is‘reduced
the choke 241 to the source of plate voltage. A.. to zero when the system »is‘in balanceand the .
condenser 259 by-passes alternating currentl 5 '14 cycle -phasing current which came vto .the
around the choke 241 and the .source o_fï power v surface yas* 592 cycle current modulated by the
' to ground.
' frequency of the vibrator or `„variable.condenser
Any alternatingv current that passes
in the well. This current, however, was recti
on through the choke is by-'passedA around. the
-battery by a _condenser _268 to ground. '
wfled. in the full wave rectiñer 262 and the high ._ .
The core of this .second .transformer 258 is
also grounded and the secondary is of the split
type with its kcenter tap grounded through. a
„ now is of the same frequency of the signal cur
resistor
26|.
_
'
frequencyremoved in the `ñlter 263 so that Ait'
rent.' The signal‘current has been divided into
_ ` two equal components by the center tap trans->
'
The end taps-of 4the output _of the' trans- 'K former 238' and is applied across leads 282, 283
~former 258 are connected to the-’plates of a 15 ’and284 at the right hand end of Figure 13. The
double diode 262, the cathodes of which are both ` phasing current from panel 3511s> applied at the
righthand end` ofv Figure v13 across the leads 285
grounded.- The Juli wave rectiñed voltage
taken from across the resistor I26| -is passed
through a band pass iilter -263 and thereafter
-
and 286.
`
>.Two double, rectifier tubes 281 and 288 are
connected in the bridge circuit so that current
used for the control of the controlïgridroffa-l
second pentode 264. lThis band pass iilter is c can flow only in'an anti-clockwise direction as
shown in‘Figure 13.. Leads 282 and 284 are
connected to opposite corners of this bridge so
as to apply the full signal current across it.;
arranged .to pass-only currents of around; '14
_cycles frequency, so that only the 74 cycle en
»velope of the phasing current passes. to the 'next
tube. A grid 1eek resistor assis connected be 25 One, of the = other corners "of the bridge is
grounded. and the remaining corner is. connected
tween the control grid of this pentode and..
ground..
y
»
o
, through apair of equalvresistances 289 and 290
Thel suppressor grid of the pentode 264 is con
to ground. vvWith the circuit as so far described
current' from the signal circuit may flow veither
vnected to the cathode which is inoturn connected '_ '
to ground through a resistor 266.across which 30 through one of the rectifier tubes or through
the other depending upon its direction but it
j can never flow -through both rectiflerxtubes at
the same time since the tubes are-arranged for
a choke 268 and resistors 269 and 21|) lall con
flow in opposite directions. Therefore current
nected in series. Alternating' current is removed
tothe ground through a condenser 21| con 35 willfnever flow from the ground across the bridge
and through the resistors 289 and 290 and volt
nected into the circuit between the Achoke 268
is shunted' a condenser 261. Plate voltages are
supplied from the source. of voltage -246 through
age will never ?be developed across these re
and the/first resistor.. 269 and by` a rcondenser
sisters.
`
212 connected into the circuit between the two
In
addition
to
the
circuit
„so
far
described, how- i
.resistors 269 and 210., Voltage i'or> the screen 40
ever, the center tap connection 283-from the'sig-`
grid is taken from a point between the choke
268.and kthe resistor 269 through a resistor 213.A '
Alternating current from the screen grid is .dis-l
charged to ground through a condenserg214».
nal circuit is' connected tothe connection 285
which goes to the phasing current circuit and
the connection286 from the phasing'current cir
Voltage is supplied for the control of the next 45` cuit is connected to ‘a point between the resistors
289 and 290. Now, if phasing current were ap
4amplifier tube 211 which isv of the beam power
type by a circuit comprising a condenser 215 andv plied and no signal current were applied the pc
tential 'would be applied on one side through
a resistor 216 connected in series between ethe-_
the lead 285, through the windings of the trans
plate of the/pentode amplifier tube 264 and
ground. The control grid of the beam power 50 former of the signal circuit and the leads 282
and 284 to the upper and lower corners of the
amplifier, which is designated> 211, is connected
bridge,
winch would thus be brought to substan
directly Vto this circuit'atfa point between the
-tially the same potential.’ A diiîerent potential
condenser and the resistance. Cathode- and the
would be applied through the lead 286 and the
beam plates are connected .directly together in
this tube and grounded'thr'ough a resistor 218 5 Ul resistor 290 vto ground and resistor 289 to the
righthand >corner of the bridge so that the right
shunted by a condenser 219. 'Current from the
jhand corner and the lefthand corner of the bridge
plate of this tube flows through the primary of
would be at the same potential, which potential w
a transformer 280 and through the choke coil
would be 'different from that at the upperA and
268 to the source Aof power 246. .The screen grid
of this tube is connected into the .platecircuit 60 lower corners of the bridge. Under these circum
stances current would ilow in two oppositel legs
below the transformer primary.
e
of the bridge but the circuit would be balanced
The core of the transformer 280 is grounded
and hence no voltage would be developed across
Y as are the cores of the other transformers and
the combination of resistors 289 and 290 because
`the output of the -transformeris conducted to
the currents through them would be equal and in
` panel 36. for comparison with the output of panel ; r
34. 7A meter 28| may be _connected across the
output of this ampliiier'for the purpose of check
_ing the Aamplitude of the output.
Reference will now be had to Figure 13 vfor a
opposite directions.
,
Suppose, however, for purpose of illustration,
that both signal current and phasing current are
simultaneously applied, and suppose for the pur
pose of illustration it is considered that the lead
detailed description ofpanel 36, which includes 70 282 becomes positive as compared to the lead
the circuit forcomparin'g the outputs of panels
284 and the vlead 285 becomes positivetás com-'
34 and 135 and adjusting the flow of direct cur
pared to the `lead 286. When thevlead' 285 be
rent to null the system. This panel also fur
nishes the current which operates the recorder.
The currents'from ’panels 34 and 35 enter
comes positive current tends to flow through the
lead '283 and the secondary of the transformer
of the signal circuit through leads 282 and 284
1o
_and through‘thel'upperhalf of the‘recti?ler 288
«which in turn reduces'the plate current in the
` fand the’ iowe; half of ‘the rectiner 281. 'That
tube 293 until a stateof balance is reached.
which tends to flow through' the lower half of -rec
f This balancing operation is assisted and the re
vtifier 281 tends:to pass to groundand'upward
„corderl operated by’ antitherI pentode 'amplifier
through the resistor290 back into the line 288. 5 tube-305, the plate of whichfy is connected to the
positive's'ide of the power source 298 and the cath
ode of which is'connected to the negative side
' 'l That which tends to passthr'ough the upper half
of rectifier 288 tends to pass through the resistor
_289l and back to thelead 286 _thus balancingthe
' of thesame power source through the resistor
ï 'current flow in the' resistors. " If' we now ‘add-the
302, a variable resistor 306, a' fixed resistor 301
current iiowing _' in the signal circuitf'we find 10 and ameter 308.l vThe recorder `is operated in ac
` that it tends to- pass through‘the upper -half of
cordance with the current in'this circuit by being
the rectifier' 2,88 in.the same direction as the
connected directly across the variable resistance
l . phasing current, but it also tends to pass through
306. By varying this resistance the recorder re
the lower part .of rectifier 281, to get to the
sponse Vmay Ibe readily adjusted. f'
-lead 284. If it did'\.this, however, there would 15 , » The control ‘grld'of the amplifier 305 is con
then 'be current passing both directions through
nected alternatively through one of three resistors
lead 284, which cannot be, so the two currents
309, 3I0 and 3| I, each having a different resist
L tend to offset each other and now is consequently
reduced in the lower halves of the* recti?lers until
one or the fother has no flow through it. This
ance, by a switch 3I2 to a point in the plate cir
cuit of the _first yamplifier 293 between the power
.source 298 and the‘resistor 299.
y -'means a consequent reduction in current flow
' through the lower half of rectifier 281 to ground
and a reductionin the- current 'in the lower ‘re-I
sistor 290. At the same time, since the current
through the upper half of the rectifier 2_88 must 2
go somewhere it passes through the resistor 289
and back through the phasingcircuit trans
former, thus increasing the current flow in resis
tor 289.'
Thus as the
plate current in-'the first ampliñer tube 293 is
raised-the voltage'of 'the‘controlfgrid of the tube ‘
305 is also raised at a rra'te depending‘upon the
value of the resistors 309, 3I0òr `3II that is con
nected in circuit with it.
The ,plate current of
the tube k305 therefore, increases and aids the plate
»current of the first amplifier 293 to bring the
'measuring circuit into balance. At the same time`
this plate current governs> the action of the re
We now have a situation where the currentv 30 corder.A Alternating current- that gets'into the
flow through resistor 289 is increased and the
grid circuit of the second amplifier 305 is ground
current flow through resistor 290 is decreased.
ed through condensers 3I3 and 3M, the ñrst of ~
v’I’hus the voltage drop across resistor 289 becomes
which is connected between the gridgof the am
greater and a positive overall voltage is developed _ plifier and a point between resistors-302 and 303
across the pair of resistors. It is therefore evi
in the well circuit and thesecond` 'of which, con
dentthat the existence of the two voltages, in
denser _3 I 4, is connected from this point to ground. ¿.¿L
phase, creates a voltage across the two resistors
For the purpose of adjusting thecircuit in the
289 and 290 whereas the absence of either voltage
beginning a grounding) switch`3I5 is provided be- ,
or their being out of phase preyents the devel
„ tween the control grid of the amplifier tube 293
-opine of voltage.
,
4m, and the ground. With this switch closed the cir
' 'I'he voltage across these resistors is taken
v cuit may be manually adjusted by reference to
the various meters so that normal amounts of
through a low pass ñlter 29 I and applied'through
a resistor 292 to the control grid of a pentode 293.
A grid leak resistor 294 is placed across the out
put of the filter. A condenser 295 is connected
between the control grid of the tube _293 and
ground to still further eliminate alternating cur
rent.
.
current will flowin the various circuits. When
the grounding switch 3I5 is opened the auto
matic control circuit begins to function.
No attempt has been made to give character
istics of resistances, condensers, chokes, trans
`f‘ormers, power sources, amplifying tubes, rectify
'
The cathode of the -amplifier 293 is connected
ing tubes or the like, since it will be obvious to
lone skilledlin the art that these may be varied
through a resistor 296to ground and the screen
and suppressor grids are connected to the plate
" which is in turn connected through a meter 291
to a source of voltage 298 which in turn is con
widely in accordance with the wishes of the de
signer of any particular instrument. Likewise,
constructional details of the various amplifying
' nected through a resistor 299 to va potentiometer
and controlling circuits have been omitted since
they also are subject to wide variation. Many
of the details that have been shown can also be
300 shunted across a `second source of potential
30| and the negative side of which is grounded.
`Thus the plate of this amplifier has applied to it
v changed'without departing fromthe spirit of this
‘a voltage which can be controlled by the setting ,
,of theîpotentiometer 300. . I
invention but most of these details have been
‘
`-Direct current is ‘taken from the plate circuit
60 found useful in the practical instrument and
therefore are believed worthy of illustration. It is
to be understood, however, that this invention is
not limitedto any specific details except as speci
of the amplifier 293 and. sent back to the well
through the supporting> cable from across the re- «
`sist0r`299, the potentiometer-300 and the bat
»tery 30I, by connections extending to the left- .
hand edge of Figure 13. One of these connec
65
y fied in the appended claims.
We claim:
1. Apparatus for well surveying that comprises
tions is grounded and the other includes a re
an instrument adapted to be lowered into a well,
sistor 302, a resistor 393 and a meter 308. As
a cable for supporting said instrument in the well
the plate current of the tube 293 increases the
and connecting it electrically to surface equip
potential drop across the resistor 299 increases
and thus the voltage and current sent to the in 70 ment, surface equipment responsive to measure- '
ments made by said instrument and a recorder
strument in the well is increased. Assuming
operated by said surface equipment, the instru
that’the correct phase relation had been estab
rient in the well including an ionization chamber
lished between the phasing current and the sig
nal current this will tend to balance the system ' responsive to` radioactive -radiations, connected
in the well and thus reduce the signal current 75 into a null system circuit the balance of which
~
,
v
v
è
.
-~‘
2,349,225-‘3' - '
'
11
y
jisjaàapted wbeadiumd Aby the surfaceequip
y or which 1s- adapted to be adjusted .by/the sur-
ment, and means for sending signals of 'a plu
_ ‘rality of frequencies to the‘surface forV indicating
l. face equipment, means for determining the state
' lof lbalance of the null system circuit, means for
f whether ornotzthe null system is in balance and
. converting this determination_into alternating
if» _notfthe 'direction of unbalance.,
`
1
current of a constant frequency and'transmit
" the ~alternating current ~to the surface,
means for generating a s_ecoiiii'alternatlng cur
'
'2.- Apparatus for well surveying that Vcomprises ’
I* an -instrument adapted-tè be lowered intol a well,
¿a Ícab'le- for supporting said instrument in-the
' rentvoi'.y a higher frequency modulatedi bythe ,
frequency -of the iìrst'mentioned alternating cur- _
ï -` well and connecting` hit electrically to' surface
equipment, surface equipment responsive' to 10 rent, ymeans ¿for transmitting the modulated
higherlfrequencycurrent to the surface'r means
in the surface equipment forv comparing the
¿measurements made by said' instrument and .-a`
A'recorder operated bysaid-surface equipment, the i
instrument in the well including an ionization
-ph'aseof the-lower frequency component ofthe
which isI adapted to be adjusted by the .surface
equipment, and means 'for sending to the sur- ‘
null; system, Vand means in the surface' equip’- ‘
ment for automatically bringing the null system i
face over a single‘pair- of conductors, signals'of a l
to balance.
high frequency .current with the lower frequency.
chamber responsive to radioactive radiations, con
nectedintp a null. system circuit the balance of 15. currentto determine the state of balance of the '
;
,
¿. _
l
6. ._Ap'paratusfor well surveying that comprises
plurality of frequenciesÀ indicating whether '.or
, not the null system is'in balance and if not, the 20, an instrument adapted to be lowered into a well,
direction
of > imbalance.`
.l
-
,
.
'
"
a’cable for supporting said instrument in the
Y
well and connecting iis-electrically to surface '
3. -Apparatus yfor well surveying that comprises
an instrument'ad'apted to be lowered into ax'well, s Y equipment, _surface equipmentl responsive 'l to
a cable lfor supporting said instrument in' thefwëll
and connecting ‘ it electrically 4‘ to> ‘surface equip
vmeasurements made by saidfinstrument and a
-25 recorder operated by said surface equipment, the
instrument ,inv theA well including an ionization
`ment, surface equipment 'responsive tomeasure--
`chamber responsiveu to radioactive radiations,
\ ments made by said instrumentandja recorder
#connected into a null system circuit, the balance
of which is adapted to be adjusted by theI surface
responsive to radioactive radiations, connected 30 equipment,` means for determining the state of
into, a nullfsystem circuit the. balance of which , balance of the null lsystem. circuit, means for
converting this determination into alternating@`
_is adapted to be adjusted ‘by the surface equip
>current
of ka constant frequency and transmit
f ment, a means for sending to the surface over a
ting,l
the
alternating
current' to the surface, means
single' pair of conductors signals indicating
for >generating’a second alternating current 'of
whether or not the null system is in balance and »
a higher frequency modulated by'the frequency
if not, the direction of unbalance, and means in ‘ n of the'ñrst mentioned alternating current, means »
operated by said surface equipment, the instru--
ment in thev well including an ionization chamber ‘
» the .surface> equipment for sending back to the’ '
_for transmitting the modulated higher frequency
_ instrument a balance controlling current for the,
current Lto the surface, means in the surface -.
'- null system over the snme pair of conductors.l
40 equipment for comparing thephase ofthe lower
. * 4. Apparatus for -well surveying that comprises ' frequency ,component of the high frequency
an instrument adapted to be lowered intoA a well,
'current with the lowerfrequency current to de
a cable for :supporting said instrument in the well
' termine the state of balance of vthe null system. v
and connecting it electrically to surface equip
and for operating a recorder in accordance with
ment, surface equipment‘responsive tqmeasure ,45 the adjustment necessary to bring the null sys
ments made by said instrument and a recorder-
tem toV balance.'
operated by-said surface equipment; the instru
'
'
f
7. Apparatus for well surveying that comprises _
ment in the well including an ionization chamber
an .instrument adaptedr to be> lowered into ‘a
lwell, a cable for supporting said instrument in ,
responsive to radioactive radiations, connected-
into a null system circuit, the balance of which Mis 50 the well' and'connecting it electrically to surface
adapted to be'a'djusted by the surface equipment,.
equipment,” surface equipment responsive v.to '
means for determining the state of balance of the
4'null system circuit, means for converting this
' measurements“ made by said instrument and a
' recorder operated by saidv surface equipment,
determination into alternating current of a-con
the instrument in the well including- an ioniza
" stant frequency and transmitting the alternating 55 tion chamber responsive to radioactive radia
current -to the surface, means for generating a , 'tions, connected into a null system circuit, the
second alternating currentof a higher frequency
balance of whichisxadapted'to be adjusted by
' 'modulated by the frequency of the first men
the surface equipment, and means »for sending
signals _of a plurality of‘ frequencies to the sur
face for indicating whether or not the null sys
tem is in balance'and if not,~ the direction o_f un
balance, said instrument in the well comprising
tioned alternating current, -means for transmit
` *ting the modulated higher frequency current'to
' the surface, and'means in the surface equipment
,for comparing the phase of the lower frequencyl
` component of the high frequencycurrent with the
- an elongated ‘tubular steel casing,'one longitudi
nal section of which is completely occupied by
the ionization chamber and another longitudi
f lower _frequency current to determine the )state
of balance of the'null system.
5. Apparatus for well surveying 'that comprises
an instrument-adapted to be lowered into a well,
a cable for supporting said instrument in the
onal section of, which encloses the null system cir
,
v cuit.
’
8. Apparatus ‘for well surveying that comprises
an instrument adapted to be lowered into a well,
well and connecting it electrically to surfacev
equipment, surface equipment -responsive to 70 a cable for supporting said instrument in the
measurements made by said-instrument and a '
recorder operated by said surfacee'quipmena'the
well and connecting it electrically to surface equip
ment, surface equipment responsive to measure
-instrument in the well'includingan ionization
‘ ments made by said instrument and a recorder
«chamber responsive to radioactive radiations,
operated by 'said surface equipment, the instru
connected into a null system circuit, the balance 75 ment in the well'includin'g an ionization cham