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Патент USA US2403955

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July 16, 1946.
K. SCHLESINGER
I
2,403,955
ELECTRON TUBE CIRCUIT
Filed May 11, 1943
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ELECTRON’TUBE CIRCUIT
Filed May 11, 1943
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Filed May 11, 1943
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ELECTRON TUBE CIRCUIT
Filed May 11,,1945
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ATTORNEY
2,403,955
Patented July 16, 1946
UNITED STATES PATENT OFFICE
2,403,955
ELECTRON TUBE CIRCUIT
Kurt Schlesinger, West Lafayette, Ind., assignor
to Radio Corporation of America, a corporation
of Delaware
Application May 11, 1943, Serial No. 486,521
34 Claims. (01. 177—-352)
1
2
The present invention is directed to electron
tube apparatus. It is particularly concerned with
circuit arrangements adapted primarily for
amplification, although many other uses, which
known types of ampli?ers cannot fulfill, will be
set forth by these speci?cations.
Such apparatus may be generally considered
“groups” operate simultaneously with regard to
the energizing voltage, but that the signal wave
passes through. the tubes sequentially. The divi
sion hereinabove made with regard to the two
as involving a type of circuit incorporating a plu
to the next. succeeding stage, and so so. Within
rality of grid controlled recti?er tubes which, may
the meaning of the above explanation, the broad
classi?cation of “groups” will be understood in
be arranged in cascade and all of the tubes are
condenser loaded. All of recti?er tubes of the
cascade are so controlled as to operate in se
quence. The circuit is so arranged that each
recti?er has its grid or control electrode con
nected to the preceding condenser and the charge
in the ?rst condenser is repeated in all following
condenser stages.
In. the system, the operational sequence, in its
groups of tubes comes about by reason of the
assumed A. C. operation. The operation essen
tially is sequential signal transfer from one stage
its generic sense and each “group” may thus in
clude one or a plurality of tubes.
It accordingly is apparent that the circuit here
in to be set forth operates with delayed outputs,
in contrast to the practically simultaneous input
and output of the usually known ampli?ers. The
present circuit operates, as will be seen, with
~ linearly averaged effects of input control energy
so that it may be used; as a D. C. ampli?er as well
carries through to the last tube, with the total 20 as an A. C. voltmeter. In the latter case, it ex
broadest sense, starts with the ?rst tube and
sequence time being substantially equally divided
hibits inherent selectivity and phase response
between the several tubes. The tubes may then
be rendered operative in sequence by an appro
which makes it readily adaptable to use as a
priate
distributor mechanism or, more con
locator or protective signalling device.
Generally speaking, the arrangement as it is
veniently, as will hereinafter be set forth, by an ‘ set up is so constitutedv that the rectifying tube
circuitsare grid controlled but operated with the
appropriate source of alternating current supply
plates or anodes supplied with alternating cur
ing operating voltages to the tubes to permit. op
rent voltages of predetermined and suitable fre
eration on the positive half cycles. With such
operation, an indication at the last tube of the 30 quency which. is, to some. extent at least, de
pendent upon the use to which the circuit is to
sequence will be the result of. some signal. control
be put. The tubes of the sequence have the
effective on the ?rst tube of the sequence anum
cathode elements thereof alternately connected
ber of cycles of operation prior to the observance
either to the positive or to the negative ter
which. is equal to the total number of tubes in
minal of the A. C. supply energy source. The
the sequence.
tubes are all connected so that the plates or
With this arrangement, the system may be
anodes connect to the supply energy source
considered as incorporating a plurality of tubes
through energy storage circuits, and each plate
arranged in at least two “groups” by virtue of
or anode connects directly to the grid or control
alternate connection of the anodes and cathodes
electrode of the next tube. rl‘hus, all tubes sub
of successive tubes of the cascade to the source
of alternating current.
In this way, the tubes of ‘
alternate “groups? operate simultaneously in that
all tubes whose anodes are connected instantane
ously to receive the positive half cycle of the
alternating current wave will be operative, while
those tubes whose cathodes. are connected to re- L
ceive simultaneously this same half of the alter
nating current wave will be inoperative. During
the following half. cycle of the alternatingv cur
rent. the operation will be reversed, and. so on.
In this way, the various tubes. may be considered
as being- arranged in, at least two: “groups?” with
the tubes of alternate “groups” operating simul
taneously. In connection with. the mode of op
eration hereinahove mentioned, it should. be
pointed out that the tubes in the different
quent to the ?rst of the plurality are arranged so
as to be controlled by an electrical charge ac
cumulated by the preceding storage circuit which
is charged under the initial control of energy
?owing in the ?rst tube. In the usual form, the
storage circuits comprise primarily a condenser
element which is shunted by a resistance or a
correcting inductance element, which condenser
is arranged to retain its charge for at least the
period of the alternating current supply wave
which supplies operating voltage to the tube
plates or anodes.
Thus, it is‘ an object of the present invention
to provide a highly selective electronic ampli?er
operating’ in such a manner that the plates or
anodes thereof are energized by an exciting alter
2,403,955
3
nating current of any desired frequency ranging,
for instance, from that of the ordinary power
supply lines or mains, for instance 56 or 60 cycles,
to frequencies of ultra-high value.
Among the more speci?c objects of my inven
tion are those of providing an electronic ampli?er
arrangement; which particularly adapts itself for
use in the detection of ?eld strength variations,
and particularly in an alternating current ?eld
A still further object of the invention is that
of providing apparatus for use in geodetic work,
and particularly for locating water, oil or ore.
A further object of the invention is that oi
providing a system which does not alter its opera
tional phase, and therefore, the number of stages
of the ampli?er is substantially immaterial, ex
cept for the degree of ampli?cation desired and
the sensitivity of response.
having substantially the same frequency as that 10
A further object of the invention is that of
of the energy supply frequency.
providing an electronic circuit arrangement
A further object of the invention is to provide
which will function as a radio receiver with sub
an electronic ampli?er circuit particularly adapt
stantially constant band width no matter which
ed for the production of single side-band trans—
of a plurality of carrier frequencies is received,
mission systems.
and a further object of the invention in this con
Another object of the invention is that of pro
nection is that of providing an audio amplifier
viding an electronic tube circuit particularly
with a substantially constant band width.
adapted for the measurement of direct currents
Other objects and advantages of the invention
and direct voltages, and thus particularly useful
in connection with photo-electric tube measure
ments, thermo-couple measurements, ionization
and the like.
A further object of the invention is that of
providing an electronic tube circuit particularly
adapted for detecting magnetic or electrostatic
?eld disturbances so that the tube circuit itself
is capable of providing an indication of the actual
location and distance of the point from which
the disturbance was initiated. In addition, it is
an object to develop a tube circuit which shall be
capable of simultaneously indicating the source
of a plurality of simultaneously occurring dis
turbances.
The system, in its preferred form, is not only
capable of making measurements of the type
hereinabove named, but is also so constituted as
to be capable of reducing measurements of dis
will immediately become apparent to those skilled
20 in the art from a reading of the speci?cation and
the claims, taken in connection with the draw
ings, wherein,
Fig. 1 is a circuit diagram of a generalized form
of the circuit of a two-stage ampli?er;
Fig. 2 is a modi?cation of the circuit of Fig. 1
provided with additional ampli?cation stages;
Fig. 3 is a graphical analysis to indicate gen—
erally the principles upon which the system oper
ates;
Figs. 4a, 4b, and 4c are a series of curves to
indicate generally the phase and frequency re
sponses of the systems of the character shown by
Figs. 1 and 2, for instance, to indicate the possi
bilities of alternating current measurements;
Fig. 5 is a modi?cation of circuit of Fig. 2 utiliz
ing coupling circuits and alternating circuit bias;
Fig. 6 is a modi?cation showing the general
form of circuit of the preceding ?gures used in
to ones of capacity, inductance or resistance.
connection with a photocell;
Still a further object of the invention is that 40
Fig. '7 is a further modification showing the use
of providing measuring apparatus particularly
of a circuit embodying the principles of preceding
useful for making all types of alternating current
circuits in connection with alternating current
measurements, such as inductance, capacity, re
measurements;
sistance, voltage current, phase and the like.
Fig. 8 is still a further modi?cation of the cir
Also, the arrangement herein to be disclosed is
cuit to show the use in connection with phase
tance, elevation, thickness, pressure and the like
generally capable of providing for making pH
shifting measurements;
measurements and furthermore indicating the
sign of the pH.
A still further object of this invention is to
Fig. 9 is still another modi?cation showing the
use of the principles of the preceding circuits in
connection with loss measurements;
provide a circuit and apparatus for use in locating 50
Fig. 10 is a schematic representation of a circuit
the presence or position of intruders in electro»
utilizing storage principles functioning as a speech
static or magnetic ?elds. In such arrangement,
ampli?er:
the system is particularly adapted for locating
Fig. 11 represents still another modi?cation
submarines, land and sea mines. airplanes in
with inductive coupling;
55
?ight, and for use as collision prevention between
Fig. 12 is a series of curves intended particu
airplanes, as well as for indicating the path of
larly to indicate the operation of the circuits of
direction of motion of airplanes, motorcars and
Figs. 10 and 11;
all forms of transports on land, sea and in the air.
Fig. 13 indicates a protective system of the
A further object of the invention is to provide
omnidirectional type;
an electron tube circuit particularly adapted for 60
Fig. 14. is intended to show the application of
measuring altitude or elevation, for instance, the
the circuits of the preceding ?gures used as an
elevation or altitude of airplanes relative to
altimeter;
ground through an indication of the capacity
Fig. 15 is intended to indicate the use of the
changes between the airplane and ground. In 65 storage ampli?er in the preceding figures in con
nection with a locating device;
this connection it may be pointed out that the
system is, generally speaking, somewhat more
Fig. 16 illustrates the storage ampli?er used
sensitive in the region reasonably near ground,
as a direction indicator;
Fig. 17 is a modi?cation of the arrangement of
although it is generally useful, irrespective of the
Fig. 16;
actual height from ground.
Fig. 18 represents one form of the circuit used
As a further object of the invention the system
as a bi-directional electrostatic collision protec
is to be designed for use in connection with the
tion device;
protection of buildings and for protection against
Fig. 18a is a series of diagrams to indicate the
when an object is moved within the ?eld of the
equipment.
conditions of the indicating tube of Fig.
75 iiesponse
8; and,
2,403,955
5
.6
the tube I. The current ?ow through tube I is.
Fig. 1-9 shows a. modi?cation providing a dif
ferent form of bias for the first stage.
Referring now to the drawings, and ?rst to
Fig. 1 thereof, there is shown a general circuit
arrangement including only two tubes which will
in turn, controlled by the average grid voltage
existing during the half cycle of conduction as it
appears across the grid leak resistor 24 as con
trolled by the impressed voltages at the input ter
minals 22. However, during the next half cycle
of the alternating current energy impressed
through the transformer secondary HI, it is ap
parent that
opposite state will exist so that
the conductor I2 will become negative relative
indicate substantially the general operational
principles of the invention as above outlined. 'In
the arrangement of Fig. 1, there are provided
two separate thermionic tubes vI and ‘a which may
be of any general and desired type, and which
to the conductor 25, and thus the anode or ‘plate
have herein been illustrated. schematically ‘as
I5 of the tube 2 will become positive relative to
tubes of the general triode type, although it is
cathode element I3. Accordingly, the charge im
to be understood that any suitable multi-elec
pressed in the condenser 3 by virtue of the previ
trode tubes may be used with equale?iciency.
In the output circuit of the tube vI, there is 15 ous half cycle period of conductivity of the tube I
will be measured by the tube 2 which now becomes
provided a storage circuit comprising a condenser
conductive. It should be borne in'mind that the
3 and a resistance 4 which shunts the condenser.
bias on grid I4 is constant (or approximately
This parallel combination of resistance and ca
thereso) due to the fact that the time constant
pacity is connected, on the one hand, to the anode
or plate 5 of the tube I, and, on the other hand, 20 of circuit .3, '4 is long. This then provides a cur
rent ?ow into the storage condenser I6 which will
byway of the adjustable contactor 6 to a desired
be a measure of the charge of the preceding con—
‘tapping point on a potentiometer 1. One ter
denser 3. It will be appreciated that if a direct
minal of the potentiometer connects to the oath
current is impressed at the terminal 22 it will
ode 8' of the tube vI by way of the conductor 9
appear
ampli?ed in the average plate current of
which is, in turn, connected to one end of the 25
tube 2, provided the time constant of the circuit
secondary winding ll! of a transformer ‘II, and
comprising the condenser 3 and the resistor 4
the other end of the potentiometer 1 connects by
is longer than, or at least equal to, the period of
way of a conductor I2 to the opposite end ter
the alternating current wave supplied at the ter
minal of the transformer secondary winding 10
minal points 20.
0
and also to the cathode wL3 of the tube 2- ~
Normally, in the circuit hereina-bove disclosed,
The control electrode 14 of the tube 2 is con
u
there is a direct current voltage drop across the
nected both to the plate or anode 5 of the tube
resistor 4 which is due to the mean value of the
I and to the condenser or storage element 3, and
plate current ?owing from the tube I. This volt
the ‘plate or anode lb of the tube 2 connects to
another storage circuit including the condenser 35 age drop normally would .block the tube 2, com
pletely, unless it is compensated for by a suitable
IB and resistor ‘25, to one terminal of which an
bias. It has been found, however, and is a fea
indicating element (assumed to be the meter t5)
ture of this invention, that the unblocking of the
connects. The condenser of the storage circuit
tube 2 may be effected by an alternating current
has its other terminal connected to the second
terminal of the transformer secondary I0 through 4.0 voltage as well as by the direct current voltage,
provided that the alternating current voltage is
conductor 25, as does the cathode S-of tube I and
in the right phase with respect to the power sup
the conductor 9.
ply of the second tube. Such conditions may be
Alternating current energy for energizing both
ful?lled by the use of the potentiometer l which
of the tubes I and 2 is supplied to the transformer
is set to such a value that the plate current to the
primary i9 by way of input terminals 20 upon
tube 2 assumes its mean value in accordance with
which alternating current energy of any suitable ‘
the current ?owing in the tube I. It is impor
frequency is impressed. Input signals which are
tant to note that the A. C. voltage drop between
to be ampli?ed, for ‘instance, are impressed by
the tapping point IS on potentiometer l and con
way of the input terminals '22 so ‘as to be ap
ductor I2 has the same effect .as would have an
plied to the control electrode 23 of the tube I
equivalent D. C. bias or battery between these
across the resistor 24 which connects at one end
points.
to the control electrode or grid 23 and at the
‘The two currents then change in the opposite
other end to the cathode 8.
'
sense, if the system is at balance under the con
The system hereinabove described is believed
trol of an input signal voltage to be measured.
to operate in the following manner:
Assume, for instance, that ‘the alternating cur 55 Accordingly, it may be seen that the system de
rent energy applied through the transformer H
is supplied so that the conductor I2 is positive
with respect to ground (or conductor 25), and
that the conductor .25., which supplies the anode
scribed is capable not only of amplifying small
value direct currents or direct current voltages
impressed across the resistor 24, but also alter
nating currents or voltages, provided the fre
voltage to the tube 2 and connects also to the 60 quency thereof is approximately that of the al
cathode B of the tube I, is negative relative to
ternating current energy source connected at 20
conductor I2. It is apparent, under such cir
and the beat note (if resulting) is at least in the
cumstances, that the tube I will draw current
response range of the storage circuit, as will later
‘but that the tube 2 wil1 be blocked because the
be set forth in further detail.
cathode is of the tube 2 will ‘be carried positive 65
Referring now to the arrangement of Fig. 2,
with respect to its plate or anode I5, but with
it will be understood that like parts are referred
regard to the tube ‘I, the anode 5 will, by virtue
to by like numerals in this ?gure, as in all others.
of the application of the positive half cycle of
The arrangement of the circuit in Fig. .2 is essen—
alternating current wave impressed by the trans
tially similar to that hereinabove described in
former i I, be carried positive relative to its cath 70 connection with Fig. 1, except that the arrange
ode 8. Therefore, under this positive half of the
ment is used as ‘a multi-stage amplifying device.
alternating current wave impressed by the trans
In the arrangement of
1, each stage, such
former II, the tube I will draw current. When
as the tube 2, has its own voltage divider ‘I which
tube 1 draws current, it will charge its plate con-_
denser 3 in accordance with the emission within‘ 76 adjusts its operational bias to optimum condi
2,403,955
7
tions. If more stages are added with the circuit
of Fig. 1, each subsequent stage must be sepa
rately biased. Since subsequent stages depend
upon the preceding stages, dii?culties are present
which increase with the number of stages, To
overcome such difficulties, a self-biasing system is
shown by Fig. 2. With the arrangement of Fig. 2,
provision is made whereby appropriate bias is
applied only to the ?rst tube I of the series and
the remaining tubes 2, 39, 40 and so on function 10
as self-biasing devices.
,
8
derstood by reference later to be made to the
diagram of Fig. 3. At present, is will be seen
that the tube I has appropriate A. C. bias applied
by way of the resistor 3| and potentiometer 3B
which has its center tap connected by way of the
conductor 32 to the cathode element 8 of the first
tube I. The bias arrangement provided by the
potentiometer and its variable tap 6 (see Fig. 1.
for example) between each stage is avoided, and
only the ?rst tube of the series is maintained at
a manually adjusted. bias level in Fig. 2. If, under
From the foregoing, it will be appreciated that
any changes of control signal energy applied to
the input terminals will be ?rst observed in the
output indicator circuit I6, 2I and at the output
terminals I1 and I8 (or the indicating device 65)
at a time n/2 cycles of the supply A. C. later,
such circumstances, input signals are applied, as
in Fig. 1, to the input terminals 22, they now
where n represents the number of stages in the
system. This permits a ready control of transit
time of signals through the system by a variation ,
In the arrangement of Fig. 2, however, it will be
seen that the tube 2, representing the second
of the frequency of the A. C. power supplied at
power input terminals 20, and thus serves to
adapt the system to certain of the uses above
stated and explained further in what is to follow.
Considering now Fig. 2, it will be seen that no
individual bias control has been provided for any
of the stages, except for the ?rst one, which is
denoted by resistor 3| and potentiometer 30.
Even despite the absence of individual controls,
all stages may be made to draw equal amounts
of average emission, i. e., all stages may be made
to operate under equal conditions if only the
?rst stage is adjusted separately and critically,
affect the control grid 23 of the tube I and func
tion to control the current ?owing therethrough,
and thus determine the charging of the con
denser 3, as explained in connection with Fig. 1.
tube in the series, now functions to draw current
at times when the tube I is blocked. In this
Way, the condenser 33 of the condenser and re
sistance network 33 and 34 is then charged under
the control of the storage voltage of the ?rst
storage circuit 3, 4, and consequently, the third
tube 39 in the series will be conductive at the
same time as the first tube.
The bias on tube 39
is constant and determined by the slow discharge
of the storage condenser 33 through its shunt
resistor 34, which discharge is negligible (as was
discharge from condenser 3) during a half cycle
of the A. C. at the terminals 20. At times when
tube 2 ceases to draw plate current, it is apparent
for example, by the potentiometer 30.
that the tube 39, that is, the tube illustrated as
To show this, it may be assumed that the ?rst
the third in sequence, will draw plate current and
stage I is permitted to draw a particularly strong
tend to charge the condenser element 43 of the
emission, under the in?uence of a strong positive
condenser and resistance combination 43 and 44.
control signal at any instant. Then, there will be
It then happens that the operation is such that
an unusually strong negative residual charge
the charge is next transferred at the fourth
across its plate condenser 3 which, during the 40 half-cycle by tube 40 into its storage circuit and
next half cycle, now acts as grid bias for the next
the rest of the operation naturally follows ac
valve in the connection shown. The second tube
cordingly.
2 of the system may thereby be completely out
Alternating current voltages are applied as the
off during its supposedly conducting half-cycle,
plate voltages for all of the tubes of the series,
which follows. This, in turn, results in zero
with the alternating current energy connected at
charge across condenser 33 and therefore is zero
the power input terminal 20 and then through
bias for the next stage 39. This third stage,
the wingings I9 and ID of the input transformer
therefore, produces a strong and blocking bias
for the fourth stage, and so forth.
It will be apparent, therefore, that the average
emission and charges of the ?rst, third and ?fth
stages, and so forth, are strong, but of the second,
fourth and sixth are zero.
.
II, so that the tubes I, 39 and 4|, respectively,
have their plate circuits energized by alternating
current energy ?owing in the conductor I2 and
controlled by the stabilizer resistance 46, while
the tubes 2, 40 and 42, for instance, have alter
nating current potentials applied thereto by way
of the conductor 25.
If now, particular reference is made to Fig. 3, it
blocked off, by a strong negative signal, at the
will be seen that there is plotted a schematic
time of its supposedly conductive half-cycle.
representation of the effective grid bias on the
It is, therefore, possible to bring the entire
first tube I as the abscissae with resulting plate
system into a condition of balance, where all
current indicated as the ordinate. If now, it be
stages draw equal average emissions and operate 60 assumed that the tube I cuts off at some value of
under equal conditions, simply by setting a criti
its grid bias indicated by point a, then various
cal medium average emission in the ?rst tube I.
plate currents will flow through the tube | for
With any given input signal, this can be done by
all values of grid bias between that indicated at
applying an appropriate bias to the cathode B of
a and zero bias, which may conveniently be rep
?rst tube I. As outlined before, this may be either
resented by the line drawn between point a and
a D. C. bias, an equivalent cophaseal A, C. bias,
point I) on the curve (and marked “Tube 1”)
or a recti?ed A. C. bias, as disclosed later herein
which is the recti?er characteristic of the stage
in connection with Fig. 19. The latter is shown
with A. C. power supply. Point b in this instance
in Fig. 2. as derived from the common A. C. supply
will represent some current which will ?ow
by an ohmic voltage divider consisting of re 70 through the tube I for zero bias, which conven
sistor 3I and potentiometer 30. With the help of
tionally may be represented as current Io.
this system, the entire system may be brought into
It was above explained that at times when no
balanced condition and the output indicator 65
average current flowed through the tube I, the
to “center-scale.”
storage voltages appearing in the condenser 3
This operation will be more particularly un 75 are zero and, consequently, under such circum
The opposite distribution would hold, if the
?rst stage had been less conductive or even
2,403,955
.10
If reference be made now to the several curves
of Fig. 4, it can be seen from curves of Fig. 4a
‘that the alternating current supply frequency is
represented by a sinusoidal voltage wave desig
nated by the solid line Es which is of a frequency
stances, the tube 2 draws a current In which is
represented by the value vc. This current in tube
v2 will decrease as the average current in tube I
increases. This current in tube 2 will become
zero when the average voltage drop across the
represented by fs. If now, -a condition be as
?rst storage circuit is equal to cutoff (that is,
sumed where the controlling signal voltage shown
o-ra). The critical ?rst stage current to bring
by the dot-dash line Eilimpressed upon the input
about such a condition (cutoff voltage) is readily
terminals .22 is of a like frequency and in phase
found from Fig. 3 by reference to the “Load line”
which is drawn through the original 0 at an 10 exactly with the supply frequency Es (as im
pressed upon ithe .power terminals 29) then it
angle B where the tangent of _the angle B is
can be seen that the plate current in the ?rst
equal to the value of resistance 4. This “Load
stage has the vfor-m shown by curve 'Ip, (‘dash
line” indicates the cutoff value of primary cur
double-dot line) in Fig. 4a. Since current does
rent (I0) where it intersects the current ordinate
15 .not ?ow through the tube 1 for half of the cycle
a—c at point 1‘.
of the ‘supply voltage Es appearing at the ter
It will be appreciated that the value of bias
minals 2%], :it is apparent that the instantaneous
on tube 1 necessary to ‘provide cutoff in the secs
current ?owing through the tube l for the neg
0nd tube 2 will be that value c which is repre
ative half-cycle will be zero, as is indicated, not
sented by the point at which the ?rst tube has a
current Ic. Thus, whenever tube ‘1 draws a cur~ 20 withstanding the fact that the impressed voltage
E is applied to the input terminals 22 ‘for the
rent equal to (or greater than) 10, tube 2 is cut
full duration. The plate current 1p is not directly
o?. This happens at point (2 and the appropriate
observed, but the output measurement is directly
bias for the ?rst stage is found at point e, be
proportional to the charge which this current
neath d. Hence, the overall characteristic for
two stages is represented by the line c-—e.
25 produces in the ?rst storage condenser -3 and is
thus represented by the shaded area marked
Likewise, following the same analysis, it is ap
“Average current.” Where a cophaseal state of
parent that the next point for cuto? in tube 39
supply and signal voltages exists, then this
(the third tube) is readily found to be at the
shaded ‘area, and hence the output reading, is a
point ‘a, while the point at which maximum cur
rent flows through the tube 39 is found to be at 30 maximum, because the signal grid voltage E1
is positive during the conductive period.
point it. From what has been stated, the overall
A condition may now be ‘assumed where the
characteristic over three stages may be assumed
signal voltage E1 is vagain of the same frequency
to be represented as that line which is drawn be
is as the power supply voltage but 180° out-of
tween points 9 and h.
It is now apparent that all of the character 35 phase at the terminals 22 with regard to the
power supply voltage Es supplied at power input
istics conventionally represented for the tubes !,
‘terminals 2!]. These conditions are graphically
2 and 39 pass through, or approximately through,
represented by the curves of Fig. 4b. In this
some common point 8. where all stages pass equal
‘case, the instantaneous current ‘flowing through
current after a condition of bias vis established
on tube l, which can ‘be brought about by the 40 the tube I of the system is represented by the
dot-dash line I'pl. It is of reduced magnitude
bias value represented by the point t, which is
relative to the current represented by Ipl in Fig.
the bias applied to the ?rst stage to provide this
ea .for a .cophaseal case, because the signal ‘grid
equilibrium condition.
‘voltage E1 is now negative during the conductive
It can be seen now that the tubes of the
sequence have gradually steeper overall charac- '
period. Accordingly, the output indicator-read
teristics, with the last of a series of n tubes being
ing, which measures the area shaded under the
curve I'pi (that is, the charge across storage con
denser 3,) is smaller than was indicated in Fig.
the steepest, and which, for instance, might be
represented by the characteristic m, m, s, 1;, w.
It thus becomes apparent that the increase in
slope in the overall characteristic, which is de
sired from the standpoint of ampli?cation, is
balanced against the decrease in the range of
applied bias voltages, such as e, y, as compared to
‘4a ‘and ‘can become Zero in some extreme cases
50
of strong negative signal input.
a value 0, a of grid bias on the ?rst tube above.
However, for control bias within the range be
tween values represented at points 9 and e, ampli
The foregoing is illustrative of the fact that
the storage ‘device is ‘responsive to A. C. ‘signal
inputs, provided that they are of the same fre
quency as its supply. These principles thus be
come the basis of operation of the storage prin
ciple circuits shown and described in the re
?cation ‘may take place with extremely high un
distorted gain due to the steepness of the overall
maining ?gures of the application.
The foregoing considerations apply to condi
characteristic represented conventionally by the
curve m, :c, s, v, w.
In the foregoing description,' reference was
made particularly in connection with Fig. 3 to ‘an
explanation of the operation of the circuits of
Figs. 1 and 2, where the system was assumed
to be controlled by a constant voltage or D. C. \
signal applied to the first tube of the system,
that is, tube 1, to control the resultant output
of the system and consequently to provide ampli
?cation of that voltage at'the output terminals
l1 and. i8. The system, however, is capable of functioning under certain conditions equally well
under the control of applied alternating current
signals on the input terminals 22. To this end,
Fig. 4 will explain how A. C. observations are
achieved.
tions where the signal and supply frequencies are
If the supply frequency is given, the sys
tern does not respond to any arbitrary fre
quencies but rather only to discrete frequencies.
The circumstances for such spectral response are
ii 1.) equal.
shown by Fig. 4c. The system responds best
(greatest sensitivity) to all frequencies which are
an integral multiple of the supply frequency, with
the inclusion of direct- current (zero frequency,
ifs, ‘2]‘s, 3J‘s and vso forth, where ‘is represents
the supply frequency). The higher the signal
frequency carrier, the less will be the response,
as shown by Fig. 40. Where the signal frequency
differs from the supply frequency, the response
is reduced and becomes zero periodically.
Referring now further to the curves of Fig. 40
for a more complete understanding of the inven
11
2,403,955
tion, the response of the storage ampli?er for
various conditions for various frequencies of sig
nal input relative to the power supply frequency
is shown. It is apparent from Fig. 4c that the
ampli?er is selective.
It was above shown that the system responds
both to direct current signals and to alternating
12
In Fig. 5, a further modi?cation of the ar
rangement of Fig. 2 has been illustrated.
In this
arrangement, the signalling energy is impressed,
as in Fig. 2, across the input resistor 24 by way
of the output energy derived from a suitable load
line or cable 50, so that tube I has its control
electrode 23 energized in the manner hereinabove
current signals of the same frequency as the
explained in order to produce the mentioned
supply. With reference to curve of Fig. 40, con
charge in the condenser 3 of the time constant
ditions may be seen where the ampli?er also re
; circuit comprising the condenser 3 and the re
sponds to different frequency values selectively,
sistor 4 connected to the plate or anode element
where such frequencies extend from zero fre
5 of the tube I. The time constant circuit com
quency or direct current to extremely high fre
prising the condenser 3 and the resistor 4 is of
quencies and hear an integral relationship with
the order hereinabcve explained and the opera
regard to the energizing frequencies supplied at l 5 tion
is essentially like that described in con
the power terminals 20. If, for instance, the
nection with Fig. 2. However, in the circuit of
ampli?er is excited by direct current applied at
the terminals 22, then the response range is that
Fig. 5, additional stabilizing resistors 52 may be
included between the various stages of the sys
tem, as indicated. With the arrangement shown,
two additional stages 53 and 54 have been added
The band width covered within the shaded area
in order to be able to arrange the system in
is given by the time constant chosen for the stor
groups of twin tubes to use twin triodes with the
age circuit comprising, for instance, the con
heaters coordinated in pairs.
denser 3 and resistor 4, or, for instance, the con.
In cases where the system is energized from
denser 33 and resistor 34, and so on. If now, the i,
alternating current voltages, it is desirable to
impressed signal frequency which is applied to
make connection from the cathode elements of
input terminals 22 happens to coincide with the
the tubes to the conductors I2 and 25, as indi
supply frequency at the power terminals 20, then
cated, and consequently, separate heater current
a response, such. as that indicated at the point
paths are provided for each half of the tubes by
where the signal input frequency is equal to is, SO way of the connections through the coupling
that is, the supply frequency, will result. An
transformer windings 56 and 51 respectively.
other maximum is observed where the energizing
Also, in the arrangement of Fig. 5, provision has
signal frequency‘ is twice the supply frequency,
been made whereby various tubes may be com
although this “second-order” response will be re
bined within a common envelope and, to this end,
duced from that condition where the supply fre- I
for instance, tubes I and 39 may be combined
quency and impressed signal frequency are equal.
within a single envelope, likewise tubes 2 and 40,
The response range or band width is the same for
also tubes 4i and 53. and 42 and 54. This is
all conditions, but the gain is reduced at the signal
always possible where the total number of stages
frequency 2fs to about 33% from the ?rst order
is an integral multiple of four.
response, as indicated by the curve. Likewise, .
Since the gain from the system is extremely
if the impressed signal frequency is three times
high, and since extremely high gain, as would be
the value of the supplied frequency, the response
indicated by the curves of Fig. 3, is very difficult
will be about 25% that which resulted with direct
to control, it is desirable that some degeneration
current being supplied as the control signal
be provided within the system which can be
energy, as, for instance, for still higher orders.
achieved by means of cathode degenerative re
Accordingly, it is evident from the curves of
sistors 55 indicated. Since the system herein disFig. 40 that the ampli?er band width is, in each
closed is sensitive to alternating current excita~
instance, the same, but the sensitivity is reduced
tion, it is particularly important that suitable
with increasing signal frequency. It is also evi
shielding thereof be provided in all instances. To
dent that if the signal frequency is other than
this end, the shielding member 69 forms a hous
some integral of the‘ supply frequency, the am
ing about the complete instrumentality and all
pli?er will not respond and the ampli?er is found
cathode elements and leads, and one side of the
therefore to be selective as to the control signal
system is grounded, for instance, by the con
input. However, the ampli?er will respond to
ductor 25 connecting at point 6| which would
beat frequencies which fall within the shaded
provide
the ground of the heater of the ?rst tube
areas or regions of Fig. 40. It thus becomes ap
I of the system. It is also important that the
parent also that since the ampli?er does not re
conductor 50 supplying the control voltages to the
spond to impressed frequency values interme
grid
or control electrode 23 of the ?rst tube I,
diate multiples of the supply frequency the am
have suitable shielding which is conventionally
pli?er does not pick up static or noise occurring
within these ranges and shows a high signal to 60 indicated by shield 62. Likewise, in order to avoid
any electrostatic coupling between the primary
noise ratio performance.
winding
I9 and transformer I I into the secondary
The general curve showing the sensitivity for
thereof, a grounded electrostatic shield means,
various signal frequencies at given supply fre
indicated at 63, as is well known, is provided. In
quency is that shown in Fig. 40 by “dash” lines
this way, the ampli?er is completely insulated
connecting the peaks of selective signal response
from external and extraneous undesired controls,
at the various frequency values, and it can be
and stabilization against disturbing in?uence
shown that this is a hyperbola which follows the
thereon is provided. The excitation and resultant
general form
output, as it appears at the output terminals I1
70 and I8, and, for instance, is conventionally rep
sin (nf_,)
resented as influencing the meter 65, is due en
nf,
tirely to the control signal voltages applied upon
where n is an integral number and fs is the supply
the system by way of the input conductor 50
frequency fed into the system at the terminals 20
rather than external disturbing influences.
to power it.
75
In the arrangements of Figs. 6 to 9, further
indicated with a maximum at 100% on the curve
and included within the shaded response area.
2,403,955
13
‘modifications’ of ‘the system have been illustrated
where the storage ampli?er system is used under
the influence of signal input of the same fre
quency as its own supply. In Fig. 6, the control is
‘by way of a photo'tube which is energized by the
common supply transformer and activated by eX
ternal light directed thereupon. In the arrange
ment of Fig. '6, the phototube output is always
in phase with the supply voltage wave. In the
arrangements of all ‘of Figs. '6 through 9, the
signal frequency coincides with the supply fre
quency. As to its phase, the signal frequency
‘and supply frequency coincide in the photo-am
pli?er modi?cation of Fig. 6, while the devices of
Figs. '7 to 9 are inherently out-of-phase, but phase
shift is measured by the ‘act ‘of bringing about a
the last stage 39 ‘is at cuto?, which permits an
indicator 65 of higher sensitivity to be used.
However, if the system is somewhat non-linear
for small light ?uxes, the operation may be im
proved by providing ?ve stages (as hereinabove
indicated in other circuits) and securing the de
sired linearity by providing cathode degeneration
in each of the stages, Under such circumstances,
as disclosed by Fig. 5, the use of cathode resistors
tends to straighten the characteristic. Thus, ?ve
stages, with degeneration, provide the same pho
tosensitivity as did the three stages, but linearity
‘is improved.
Still another application of the invention is
shown in the circuit arrangement of Fig. '7, where
special provisions have been .made for use of
the device for alternating current measurements.
In the arrangement shown, the energy supplied at
the supply input terminals 213 is now fed through
cophasal condition of operation and observing
maximum output.
With the arrangement of Fig. 6, the overall
a transformer '55 which has a split secondary
sensitivity of the system is large and, therefore, 20 winding
consisting of the secondary turns 16 and
provision has been'made byway of a, variable re
it’,
respectively,
with the center tap 18 connected
sistance element 6'', replacing the input resistor
to a ground point 19, as indicated, which point
24 of the arrangements of Figs. land 2, for in
coincides with the connection to ground of the
stance, for reducing the impressed voltages which‘
cathodes
ofthe first and third tubes l and 39
are applied to the control electrode 23 of the ?rst
‘respectively of the system. Alternating current
tube I of the system under the influence oi strong
voltages are supplied to the plate electrode mem
illumination. In the modi?cation of Fig. 6, the
bers of the tubes i and 39 by way of the conductor
complete system is housed within the electro
i2, as described, ioriinstance, in connection with
static shield ‘means 63 .in which is included a win
Figs. 1 and 2, and the plate of the second tube 2
dow ‘member ‘68 through which light from an .ex 30
is grounded through the conductor 25.
‘ternal source is directed upon the phototube mem
In order to provide for making alternating cur
ber 69 contained within the housing. The win~
rent measurements, a phase shifting network,
dow 68, if desired, ‘may include a lens arrange
ment so as to focus sharply light which is to con
comprising the series arrangement of the ca
pacity element as and the variable ‘resistor 81,
is connected between the outside terminal points
of the two secondary windings it and ‘H, where
by, through adjustment of one of the elements
system.
.85} and 81, varying phase shifts may be provided
In the arrangement shown, the cathode heater
between point 8.2 and ground 19 without chang
oi the cathode of tube vl is connected to the shield an ing the voltage between point 82 and ground 19.
at point '6 l, asin the arrangement of Fig. 5. The
At point 82 the unknown impedance 83 is con
heater elements are ‘arranged in groups and are
nected ‘serially to ground ‘i9 through switch 84
separately energized by two heater coils 56, 5'!
with ‘the ‘variable grid resistor 61 which is accu
which are, in turn, connected to either of the two
rately ‘calibrated. In this way, when voltages ap
45
terminals of the secondary of the power trans
pear .at the'point 82, they are applied through the
former ll. Such connections avoid insulation
unknown impedance 83 and switch 84 to the grid
troubles.
or control electrode 23 of the tube 1 to control
The phototube 69 is so'connected that the anode
the current flowing through the tube 1 in the
element ‘H thereof connects to the conductor l2
manner ,hereinabove explained.
and is supplied with alternating current in the
In the operation of this system, the A. C. bias
same manner as the plate‘or anode 5 of the tube
is adjustable by potentiometer iii! to a value
trol the photoelectric current flowing in the pho- "
totube 63, thus .to vary the control potential on
the control electrode .23 of the ?rst tube I of the
I, so that, at times when the plate or anode 5
of tube 1 is supplied with energy of the positive
half-cycle of the alternating current source con
nected at the input terminals 20, the anode ‘H
of the phototube will also be positive, and then
light entering upon the phototube 69 to ‘in?uence
the photoelectric cathode element 12 thereof will
‘Where a cutoff condition holds on tube 39 and
meter .65 is at zero reading where the switch 84
is open (as shown). Now, switch 84 may be
closed and the A. C. signal transferred from
transformer ‘I5is impressed .on thegrid 23 of tube
1 through the phase shifting network 80, 8i and
the unknown impedance 83 in anarnplitude which
provide an A. C. voltage .drop across the input
60 depends upon .andIis proportional to the value
resistor 61 to-give a positive swing on the grid or
of the grid resistance 61. With this condition,
‘control ‘electrode 23. The input resistor 61 is
the grid resistance iii is adjusted until an indica
variable, so that the overall sensitivity may be
tion just appears on indicator v55. The phase
readily‘adjusted.
control 8i is now adjusted and, in the general
The time constant of all storage circuits 3, 4,
case, the indication on the device 65 will go
through a ‘maximum and, when the maximum is
etc., is made large as compared to the supply as
reached, the cophasal condition of grid input volt
was outlined in what is said above. Suitable A. C.
age and supply voltage is obtained. This permits
bias for the ?rst stage of the system is applied
observation and determination of the phase angle
in the same manner shown in connection with
the ‘arrangement of Fig. 2.
70 of the unknown impedance 83 which coincides
with that produced between elements till and 8|
The ‘amplifieriof this system preferably has an
and is of opposite sign to that of the elements
odd number of stages since then the output in
Bil and BI. To ascertain the exact value of the
creases with illumination ‘on the phototube 6s.
unknown impedance 83, the phase condition
‘The A. ‘C. bias is set on the ?rst stage by the
‘slider ‘of potentiometer 30, so that the bias on 75 above set by element '8! is maintained and the
15
2,403,955
16
value of the grid resistor 81 is reduced until the
frequency
range
and
preferably
of the order of
indication on 65 just disappears and then the
20 kc. or more.
unknown impedance can be calculated from the
Even if the supply frequency chosen is high,
value of resistance 61 by voltage divider formu
the system of Fig. 2, for instance, will not handle
lae. In this operation, the current flow in the ti audio
control signals because of the high inertia
outer circuit 80, BI, TI and ‘I6 is relatively large
of the storage circuits. Accordingly, the storage
compared to the current flow through the un
circuits which had a relatively long time constant
known impedance 83 to ground ‘I9 through the
in the examples heretofore discussed, must now
resistor 6‘! and, further, the grid impedance G1
be so designed that they have an extremely short
is a small fraction of the impedance 83, which 1
condition is always met with a sensitive ampli
?er.
Figs. 8 and 9 are modifications of what is shown
in general form by Fig. '7. Figs. 8 and 9 are re
lated to a showing for measurements of technical
inductances and capacitors, respectively, with
losses.
The general technique is like that ex
plained in connection with Fig. 7, except that
the push-pull transformer secondary ‘I6, 11 is no
longer required due to limited phase shift to be _
expected. In each of the arrangements of Figs.
8 and 9, the unknown phase shift may be ascer
tained from the phase retarding network com
prising the resistor 85 and the capacitor 86. The
resistor 85 is connected in the A. C’. supply lead
I2 and the capacitor connects to ground SI from
point 90 which constitutes the junction point of
connection of the network elements 85, 85. The
calibrated resistance element 8'! enables the value
of the inductance 88 Or capacitor 93 to be ascer- I
tained. In the case of the inductance measure
ment, the inductance 88 is connected between
the grid 23 of tube I and ground 9|, while the
capacity element 93 will be connected between the
grid 23 and the phase delayed plate supply for the "
tube I. With the circuits of Figs. 8 and 9, the
adjustment of elements 85 and 8B of the phase
shifting network generally is of a closely related
nature to the phase shift adjustment of elements
80 and 8| in Fig. '7. Likewise, adjustment of
resistor 81 is for substantially the same purpose
as the adjustment of resistor 61 in Fig. 7.
As in some of the preceding circuits, with the
systems of Figs. 8 and 9 it will be appreciated that
tubes I and 2 may be combined in a single enve
lope by using tubes of the general types of the
6E8 and 6J5 for instance.
In the modi?cation shown by Fig. 10, provision
has been made to use the principle of the circuits
hereinabove explained in connection with speech
transmission, as contrasted with the general type
of measuring instrumentality. In the arrange
ments particularly disclosed in the preceding
?gures, it was assumed that the control signal is
direct voltage or a constant amplitude alternat- r
ing current voltage. Under such circumstances,
the time constants of the storage circuits com
prising, for instance, the charging resistor 4 and
the storage condenser 3 connected to receive the
output from tube I, can be made relatively long.
However, in arrangements where the signal en
ergy is such that the signal strength varies, as
will be the case to be considered in the descrip
tion of Fig. 10, certain modi?cations must ‘be made
in the system. For instance, the supply fre
quency which is to energize the plate or anode
elements of the various tubes will have to ‘be of a
relatively high frequency value and at least twice
as great, and preferably more, as the highest
time constant, which is preferably less than (and
certainly no greater than) the shortest period
occurring in the signal input, meaning the period
of highest frequency which is contained in the
signal input to the system. If, for instance, it
were assumed that the system of Fig. 10 were to
be used as an amplifying arrangement for ampli
fying audio voltage signal input energy and a
high ?delity system were to be desired, then it
will be apparent that the time constant of the
storage circuits of each of the tubes should be
shorter than 30 micro-seconds, since the system
should function properly up to sound frequencies
of the order of 10 kc., and the supply frequency
then should preferably be of the order of 30 kc.
or higher.
For these conditions, the circuit shown by Fig.
10 is such that energy of a relatively high fre
quency, as above explained, is developed at the
power supply I00 and fed through the transformer
IUI to energize the conductors I2 and 25, as above
explained. The control signal voltage which now
may be audio frequencies ranging from zero to
10 kc., may now be applied to the input terminals
I03 and I04 and fed through transformer I05 to
be applied upon the control electrode 23 of the
first ampli?er tube I.
Since the system herein disclosed may amplify
audio frequency directly, or the system may func
tion as its own demodulator, it is possible to sup
ply the audio frequency signals as modulations
upon a radio frequency carrier which is impressed
at the terminals I03 and I04. Under the c0ndi~
tions where the audio frequencies are applied as
modulations of a carrier frequency, the secondary
winding IIG of the transformer I05 (which, in
this case, is a radio frequency transformer and is
contrasted to audio frequency transformer where
the signals do not appear as modulations of a,
carrier) is now preferably tuned by means of the
condenser II'I, but it will be understood that the
condenser may be omitted in the case that the
signals are supplied without being modulations of
a carrier frequency.
In the arrangement shown in Fig. 10, it is to
be understood that any desired number of stages
may be utilized, although only four stages have
been shown. Under explained conditions, with
fairly extremely high supply frequencies (for
instance, 30 kc. as at the source I00) and very
short storage inertia, the charges across the stor
age condenser circuit are able to follow even‘ the
fastest rate of change of the input signal and
are therefore transferred through the complete
system and ampli?ed in each stage until they
appear at the last storage circuit I I8 with a delay
n
1
E-W) seconds
(n=number of stages and 30 kc. is the assumed
signal frequency which is to be supplied to vary 70 supply frequency), but otherwise undistorted. It
is thus evident that the delay period is a function
the input for ampli?cation. For instance, for
of the supply frequency, so that it is subject to
speech ampli?cation the frequency of the supply
control by varying the supply frequency and thus
energy which is to energize the plates of the vari
ous tubes of the system must now be in the higher 75 can be made shorter by increasing the supply
frequency, although no changes are made in the
2,403,955
17
storage circuits or their time constants and the
quality of the reproduction suffers no change.
This system, therefore, is of the type well suited
to use as a reverberation control.
The output energy which appears across the last
storage condenser H8 is supplied to a sound re
producing element I I9 by way of the transformer
18
adaptations and uses of the principles disclosed
heretofore.
In the arrangements of Figs. 13 to 18, applica
tion of the storage principle will be disclosed in
a ?eld broadly termed protective or locating sys
tems. The common features of all of these 'cir
cuits is that an alternating magnetic or electro
coupling I26 connected across the storage con
static ?eld is set up in space which oscillates at
denser.
the same frequency as the storage ampli?er con
If reference is made at the moment to the 10 nected to the ?eld electrodes. The system is so
curves of Fig. 12, it will be seen that the frequency
balanced that as long as the ?eld is undisturbed
response of a circuit of the type of Fig. 10 is gen
the output indicator of the storage system is at
erally indicated by the curve a of Fig.- 1-2. This
equilibrium. As soon as any variation of the 'field
curve a shows that the frequency response plotted
distribution in space occurs, for instance ‘by the
against the signal frequency impressed (with the 15 intrusion of a conductive, dielectric, or ferromag
assumption that the supply frequency for the
netic body or object, the particular vproperty of
tube anodes remains constant) falls off rather
the storage principle makes it possible to indicate
rapidly with increases in input signal frequency.
that change in the ?eld, not only in magnitude
Accordingly, to improve the response, reference
but also in a directional manner. "Thus, not only
may now be had to a further modi?cation of vthe 20 the presence and distance of an object, ‘but even
circuit as shown by Fig. 11. In the circuit ar
the location thereof, is discernible.
rangement of
11, the same supply frequency
as above from the source 160 is again fed through
the transformer IQI to energize the plates of the
various tubes of the system by way of the con‘
ductors ‘I2 and 25, as already explained. (Inci
dentally, in order to provide suitable alternating
13,Inthere
the arrangement
has been disclosed
particularly
what may
shown
be termed
by
an om-ni-directional indicating or protective sys
tem, whereby the presence of any object, whether
it be conductive or dielectric, which would tend
to disturb the ?eid equilibrium may be ‘observed
and ‘indicated equally well in all directions of a
current bias ‘on the system, provision is made for
plane. In this arrangement, the supply frequency
the use 'of the series ‘condensers I28 ‘and I29
serving as a capacitive voltage divider to ‘replace 30 energy, which may be of any suitable value, ‘is
developed by a source of A.'C.‘energy ‘I50. This
the resistive voltage divider of Fig. 10. Never
source of energy [59 serves in connection with
theless, previously described bias supplies may be
used ‘at this point.
the arrangement of Fig. 13 not only to supply the
With ‘the bias system shown, provision is vmade
activating energy for energizing the plates of the
for connecting a suitable high frequency choke 35 several tubes of the storage amplifier system 1300,
as was explained in the arrangement of the ?g
I36 between the cathode element '8 of tube I ‘and
ures heretofore discussed, but it also ‘serves, as
the conductor 25 to avoid the detrimental effect
will ‘be ‘more particularly pointed out ‘later, ‘as
of the cathode to ‘ground distributed capacity,
represented at PM in Fig. 10.
the activating energy source to produce an elec
In order that the high frequency response ‘of 40 trostatic ?eld 30! in space. The produced =elec
trostatic ‘?eld may be modified through the pres
Fig. 11 shall "be improved over that “of Fig. 10,
ence of any object 'I’It'? within the field tending
the storage condenser has been split into two
to‘disturb a normally balanced condition. When
parts 3' vand I33, and an inductance element I3!
has been interconnected and placed between the 4.5 such motion occurs, a change in the energy trans
fer from the source of supply frequency I50 "to
two condensers '3’ and I33. ‘For low signal fre
the input ‘to control the ampli?er will be 'in'di
quencies, the coil or inductance ‘I3! can be neg
cated,ias will be ‘explained in what follows.
lected and the ‘storage circuit acts as in Fig. '10,
In the arrangement disclosed, ‘the .supplyfre
but for high frequencies, series resonance occurs
between inductance 'ISI 'and'capac'itor I33 which 50 quency energy from ‘the source I50 is now fed
by way of the conducting leads 152 ‘and trans
results in a peakingeifect for high audio frequen
former I5I to energize the plates or anodes of
cies. This, then, produces the improved response
the several tubes of the storage ampli?er 300 ‘by
shown "by curve 2; of Fig. 12. The inductance
way of the conductors I2 and :25, in ‘a manner
element 'I3I thus ‘serves as a peaking element,
heretofore explained. At the ‘same time, energy
and the ‘time constant of the circuit, "comprising
from the source I53 is fed by way of an addi
the capacity I33 and the inductance I3I, which
tional pair vof conductors IP53 to a primary wind
for low audio frequencies ‘is the same as that
ing I54 of a high voltage transformer I55 from
represented by the capacity 3 and resistor II in
the secondary I56 of which a substantialamount
Fig. l0,appears to be reduced for high audio fre
of energy at high ‘voltages is derived and caused
quencies vby Way of insertion of the series peaking 60 to produce a strong electrostatic ?eld (for in
inductance I3I and the response curve of the
stance represented by
system broadens out, as indicated by curve I) of
Fig. 12, during a-greater portion of the frequency
is)
band, although the response drops off more rap
idly as extremely high audio frequencies of the
between a suitable ?eld electrode element .451,
such as an antenna or the equivalent, and ground
range are approached. Similar ‘time constants
I58. The voltage between the antenna element
and series peaking inductances are provided in
I51 and ground may be represented, for conven
ience, as Es, and the capacity ‘between the an
the remaining stages of the system for like pur
tennaand ground may be indicated convention
poses, and hence ‘require no further explanation.
Here again, the number of ‘tubes or stages may 70 ally by the capacity element shown in dotted
be increased vwithout departing from the spirit
and scope of what has been illustrated.
outline as the capacity I59.
‘ '
In order to provide the voltage ‘Es on .theele
ment I51, the high voltage step-up transformer
Reference may now be made to the ‘circuit
I55 has been provided with a split secondary
shown by all the Figs. 13 through 18 for further 75 winding at which the midpoint I50 connects lbiy
2,403,955
,-
.
,
19
way of the conductor I6I to the grid or control
electrode 23 of the ?rst ampli?er tube I of the
system. The upper half of the split secondary
I56 connects at its outer end by way of conductor
I 52 to the antenna element I51, while the lower
end of the split secondary connects through the
20
other element I51, might be expressed by the
following formula:
Where
ex represents the voltage between the bridge bal
condensers I63 and I64 to ground at I58. Under
ance point I66 and ground I58;
such circumstances, the arrangement disclosed
Es represents the voltage between the antenna
provides a bridge structure with the center tap 10
and ground;
ping point I60 at an A. C. potential relative to
Cs represents the capacity of the antenna I51 to
ground which can be adjusted, and even made
ground I58;
zero, by the condensers I63 and I64. If the
it represents the height of the antenna I51 rela
bridge condensers I63, I84 are equal to the an
tive to ground I58;
tenna capacity I58, the center tap IE0 is at ground
a is the radius of the sphere or body I18 which is
potential. If, however, the bridge condensers are
tending to cause the unbalanced condition;
set to be larger or smaller than the antenna ca
and,
parallel condenser combination comprising the
pacity, the center tap voltage is either opposite
or cophasal to the ampli?er supply voltage and
r is the distance of the body I10 from the antenna
51.
increases with the unbalance. Consequently, an 20
Under
such conditions, it will be seen that the
adjustment of I63 can be found Where the out
reaching effects, and thus the e?‘lciency of the
put meter 65 reads exactly center scale, so that
system, fall off as the sixth power of the distance
a conductive grounded body I18 increases the out
of the object tending to disturb the balanced ?eld.
put reading on indicator 65 while a dielectric body
causes a decrease in the meter reading.
25 Under such circumstances, it can be seen readily
that the range of action or effectiveness of the
‘ Referring back to Fig. 4b, the curve E’1 showed
system disclosed may be reasonably large. With
an out-of-phase relationship relative to the sup
a relatively high voltage of 10,000 volts existing
ply voltage E3. The adjustment herein made is
between antenna I51 and ground I58, with the
of substantially the same general character. To
achieve the balanced state represented by a cen o ‘ antenna roughly '75 feet high and its capacity to
ground being of the order of 500 micromicro
ter scale reading of indicator 65, the condenser
farads, and the radius of the disturbing body ap
combination I63 and IE4 is preferably adjusted
proximately three feet and the sensitivity of the
substantially so as to balance the capacity I59
ampli?er represented being of the order of 0.1
as representing the capacity between the antenna
mv., it will be evident that from these assumed
or other element I51 and ground. This adjust
values the radius of effectiveness of the system to
ment is very critical and is provided by a coarse
distinguish or determine disturbing factors com
control, in the form of a large condenser I63,
ing within the ?eld of the antenna is of the order
and a ?ne control in the form of a small con
of 150 feet. This radius may be increased, for
denser I64. Such an adjustment is preferably
instance, by increasing any of the factors herein
facilitated by pro-setting once for all the larger
above noted or by increasing the sensitivity of the
of the condensers I63 and I64 and then leaving
ampli?er.
that condenser substantially ?xed, after which
Under some circumstances it is desirable to
time the smaller condenser I64 may be varied
shield certain portions of the system from in
slightly to obtain balance. Generally speaking,
?uence of disturbing motions and the like. For
the voltage developed across the complete second
this particular purpose, the schematic illustra
ary winding I56 is equal to twice the voltage
tions of Fig. 13 indicate still another shield elec
applied to the antenna element I51 relative to
trode I1I as interposed between the antenna I51
ground. In order to protect against possible
and ground I58. The shield electrode connects to
touching of the antenna element I51 or its lead
ground by Way of the connector I12, which con
in I62, a suitable resistance element I66 may be
necting element may, for instance, be the outer
provided. Likewise, in order to protect the stor
shield of a coaxial cable of which the inner ele
age ampli?er system 380 against overload, a pro
ment I62 feeds energy to antenna I51. Under
tective resistance I61 is included in the lead be
the circumstances, any object between the
tween the center point I60 and the control elec
grounded auxiliary shield electrode and ground
trode 23.
will have no effect upon the system due to the
If now the conditions hereinabove explained
shielding effect of the element I1I.
are such that in the absence of any change in
The modi?cation disclosed by Fig. 14 is, in
the capacity between the antenna element I51
many respects, closely related to that hereinabove
and ground I58, a substantially balanced state
described in connection with Fig. 13, except that
is continuously obtained, then a center scale
the system is fully insulated from ground.
reading is registered on the ?nal output indicat
Referring now particularly to Fig. 14, it may be
ing device 65. However, if now there comes with
assumed that the complete assembly included
in the ?eld produced between the antenna ele
within the housing element I88 is carried par
ment I51 and ground I58 some object, such as
that conventionally represented at I10, which
ticularly upon an airplane, so that a measure
ment of the elevation of the aircraft relative to
would tend to disturb the field, the condition of
ground I58 may easily be determined. Still fur
balance heretofore achieved by way of adjust
ther, the housing I80, for all practical purposes,
ment obtained by way of condensers I63 and I64
may be regarded as the metallic body of the air
is disturbed. The result is that the potential at
the point I60 relative to ground I58 will change 70 craft itself where there is provided an antenna
I8I, or other suitable form of electrode element,
and an indication, as above indicated, will be
such as a screen or a metal coating, electrically
produced on the output meter 65. The voltage
insulated from the ship housing proper or, in the
disturbance at the bridge point I60, which would
case of Wood airplane construction, it is formed
result from any body, such as that indicated at
as a metal coating on the outer surface thereof.
I18, coming within the field of the antenna or
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