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Патент USA US2404344

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July 16, 1946.
R. F. WILD
2,404,344
MEASURING AND CONTROLLING APPARATUS
Filed July 7, 1944
4 Sheets-Sheet 1
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INVENTOR.
RUDOLF F. WILD
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July 16, 1946.
R. F. WILD
2,404,344
MEASURING AND CONTROLLING APPARATUS
Filed July '7, 1944
4 Sheets-Sheet 2
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RUDOLF F. WILD
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July 16, 1946-
R. F. WILD
2,404,344
MEASURING AND CONTROLLING APPARATUS
Filed July 7, 1944
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July 16, 1946.
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2,404,344
MEASURING AND CONTROLLING APPARATUS
Filed July 7, 1944
4 Sheets-Sheet 4
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INVENTTR.
RUDOLF F. WILD
BY
: ATTORZEY.
HUUHI
Patented July 16, 1946
2,404,344
UNITED STATES PATENT OFFICE
2,404,344
MEASURING AND CONTROLLING
APPARATUS
Rudolf F. Wild, Philadelphia, Pa., assignor to The
Brown Instrument Company, Philadelphia, Pa.,
a corporation of Pennsylvania
Application July 7, 1944, Serial No. 543,892
19 Claims. (Cl. 172-239)
1
2
The present invention relates to measuring
and controlling systems, and more particularly,
to electrical systems for measuring, indicating,
recording and/or controlling variable conditions
ture, of the second low frequency signal voltage
nal voltage is reduced to zero when the system
is balanced or stabilized. The provision of such
such as temperature, pressure, liquid level and
an arrangement forms a primary object of the
to such a value that the mixed or resultant sig
flow, and also has utility for telemetering, torque
present invention.
amplifying, boat steering, remote control and
Another object of the invention is the provision
repeater positioning purposes.
of such an electrical measuring and controlling
A general object of the invention is to provide
system wherein the high frequency discriminat
improved electrical systems of the above men 10 ing means may or may not be of the balanced
tioned character.
type as desired.
In my copending application Serial No. 537,505
A further object of the invention is the pro
?led on May 26, 1944, I have disclosed and
vision of such a system wherein the adjustments
claimed various apparatus embodiments of an
in the second mentioned low frequency signal
electrical measuring and controlling system of 15 voltages may be eifected by variation in resist
the type described above. These apparatus em
ance, inductance or capacitance, as desired.
bodiments are characterized in that they com
The various features of novelty which charac
prise tunable means including, in combination,
terize this invention are pointed out with partic
an oscillator which generates a relatively high
ularity in the claims annexed to and forming a
frequency, means to amplitude modulate the high 20 part of this speci?cation. For a better under
frequency current at the frequency of oscillation
standing of the invention, however, its advan
of a relatively low frequency current, balanced
tages and speci?c objects obtained With its use,
high frequency discriminating means responsive
reference should be had to the accompanying
to the frequency of the modulated high frequency
drawings and descriptive matter in which is il
current and operative to create a signal voltage 25 lustrated and described a preferred embodiment
of one phase or of opposite phase oscillating at
of the invention.
the low frequency and having a magnitude de
Of the drawings:
pending, respectively, upon the direction and
Fig. l is a diagrammatic illustration of one
extent of deviation of the high frequency current
embodiment of the invention;
7
from a predetermined value, and phase respon 30
Fig. 2 illustrates the electrical circuit arrange
sive motive structure controlled by said derived
ment of the apparatus of Fig. 1;
oscillating signal voltage. The phase responsive
Figs. 3, 4 and 5 are graphs illustrating the op
motive structure is employed to adjust the fre
eration of both of the frequency discriminators
quency of oscillation of the high frequency cur
of the arrangement of Fig. 2;
rent, or alternatively, the frequency value to
Fig. 6 is a wiring diagram illustrating a modi
which the discriminating means is tuned, as re
?cation of a portion of the arrangement of Fig. 2;
quired to reduce to zero the low frequency signal
Fig. 7 illustrates a modi?cation of the arrange
voltage and thereby to balance the system.
ment of Fig. 6;
The present invention is directed to improve
Fig. 8 illustrates a modi?ed form of discrimi
ments in electrical measuring and controlling 40 nator which may be employed in the arrange
systems of the same character as those disclosed
in my above mentioned copending application.
In the apparatus embodiments of the present in
vention which have been disclosed, the tunable
means includes, in addition to the means for gen
erating a low frequency oscillating signal voltage
according to the direction of deviation of the
frequency value of the high frequency current
from a predetermined value, means to create a
second oscillating signal voltage of said low fre
ment of Fig. 2;
.
Fig. 9 is a graph illustrating the operation of
the modi?cation of Fig. 8; and
Fig. 10 illustrates a further modi?cation of the
45 arrangements of Figs. 2 and 6.
In Fig. 1 I have illustrated, in a more or less
diagrammatic manner, a measuring, indicating,
recording and controlling system for measuring,
indicating, recording and controlling the rate
of flow of a ?uid through a pipe or a conduit l.
The rate of flow of a fluid through the pipe I is
detected by a manometer which is designated at
2 and is arranged to operate a variable condenser
oscillating signal voltages to effect adjustment,
designated by the numeral 3 for detuning a res
by means of the actuation of the motive struc 55 onant electrical circuit comprising a high fre
quency which is mixed with the ?rst mentioned
signal voltage of low frequency, and means con
trolled by the resultant of the two low frequency
l
2,404,344
3
quency oscillator 4 in the frequency determining
circuit of which the variable condenser is con
nected. The high frequency oscillator 4 is uti
lized as a generator and transmitter of high
frequency current and is connected to and re
ceives energizing current from alternating cur
rent supply lines L’ and L". The high frequency
current output derived from the oscillator 4 is
of variable frequency dependent upon the ad—
justment of the variable condenser 3 and is con
veyed by means of a transmission line, which
may comprise a co-axial cable 5, to a receiver
which has been designated by the reference char
acter Ii. As will become evident as the descrip
4
varied. The change in that undulating voltage is
utilized to actuate the motive structure referred
to and that actuation is employed to rebalance
the apparatus by effecting a corresponding
change in the amplitude of the undulating voltage
produced at the output terminals of the discrim~
inator I2. This result is obtained by adjustment
of the frequency of oscillation of the oscillator
‘I by the motive structure.
In order to accomplish this result, the undulat
ing or signal voltages created at the output ter
minals of each of the discriminators I0 and I2
are impressed on a mixing ampli?er which has
been designated by the reference numeral I4 to
tion proceeds, the high frequency signal currents 15 produce a resultant voltage in the output circuit
from the generator 4 may be transmitted to the
of the mixing ampli?er having an undulating
receiver 5 by wireless or radiation as well as by
means of transmission line 5.
The receiver 6 in the embodimentof the in
vention shown in Fig. 2 includes two channels.
The high frequency current transmitted to the
receiver 6 from the generator 4 is impressed on
the ?rst of these channels and a high frequency
current generated by an oscillator 'I located with
in the receiver I5 is impressed on the second of
the channels. Of the two channels, the ?rst
includes an ampli?er 8, a limiter 9 which may
be a conventional amplitude limiter of the type
component which is zero in value or of one phase
or of opposite phase depending upon whether
the amplitude of the signal voltage produced at
the output of the discriminator I0 is respectively
equal to or less than or greater than the ampli
tude of the signal voltage created at the output
terminals of the discriminator I 2. This undulat
ing resultant voltage is impressed on the input
terminals of a power ampli?er indicated at I5
which is provided to control the selective ener
gization for rotation in one direction or the other
of a two-phase reversible electrical motor gener
employed in frequency modulation broadcast re
ally designated at I6. As shown, the motor I6
ceivers, and also a balanced frequency discrim 30 is an induction motor of the rotating ?eld type
inator III. The second channel includes the os
and is arranged to adjust a variable condenser I‘!
cillator ‘I, a buffer II, and a balanced frequency
connected in the frequency discriminating cir
discriminator I2 which may be and has been
cuit of the oscillator ‘I for accomplishing the de
shown as being identical to the frequency dis
sired rebalancing operations of the apparatus. As
criminator ID. The receiver 6 also includes a
may be seen by reference to Fig. 1, the motor I6
keyer I3 for amplitude modulating the high fre
also operates indicating and recording mecha
quency output current from the limiter 9 and
nism generally designated at I8 and control ap
the buffer II during recurring time intervals of
paratus shown at I8a which in turn operates con
an oscillation of relatively low frequency for the
trolling means designated by the character I9 for
purpose of producing at the output of each of the
controlling the flow of ?uid through the pipe I.
discriminators I 0 and I2 an output voltage un
The manometer 2 for ascertaining the rate of
dulating or ?uctuating at said low frequency and
?uid ?ow through the pipe I may be of any
of one phase or of opposite phase, depending upon
known type and, as shown, includes an ori?ce
the frequency values of the high frequency cur
plate 20 which is positioned in the pipe I for
rent output from each of the oscillators 4 and ‘I. 45 creating a pressure differential across the ori?ce
When the frequencies of oscillation of the mod
plate 20 which varies in accordance with the rate
ulated high frequency currents impressed on each
of ?uid flow through the pipe. The pressure dif
of the discriminators I0 and I2 are the values to
ferential so produced is a square root function of
which the discriminators I0 and I2 are tuned, the
the rate of ?ow through the pipe I. Manometer 2
output voltage of each of the discriminators is 50 also includes a high pressure chamber 2I which
substantially zero. As will be evident, the fre
is connected by a tube 22 to the high pressure
quency values to which each of the discriminators
side of the ori?ce plate 20, and includes a low
is tuned may be the same, or if desired, the dis
pressure chamber 23 which is connected by a
criminators may be tuned to different frequency
tube 24 to the low pressure side of the ori?ce plate
values. Variation in the frequencies of oscilla 55 20. The low pressure chamber 23 and the high
tion of the modulated high frequency currents
pressure chamber ZI communicate with each
impressed on each of the discriminators I0 and
other through a tube 25.
I2 from the value or values to which the dis
The relative levels of mercury or other suitable
criminators are tuned causes an undulating volt
liquid located within the pressure chambers 2I
age to appear at the output terminals of each 60 and 23 vary in accordance with the pressure dif
discriminator. Those undulating voltages are of
ference within those chambers, and consequently,
one phase or of opposite phase depending upon
provide a measure of the rate of ?uid ?ow through
the direction of the change in frequency. In ac
the pipe I. A member 26 which ?oats on the
cordance with the present invention the magni
mercury in the high pressure chamber 2|, and
tudes of the two undulating voltages are com 65 therefore, rises and falls in accordance with the
pared to each other and when they are of un
variations in pressure differential in the two
equal amplitude suitable motive structure to be
chambers 2| and 23 is arranged to angularly
described is set into operation to equalize the
de?ect a gear sector 21. The gear sector 21
two undulating voltages. Speci?cally, upon un
meshes with a gear 28 which is arranged to op
balance of the apparatus due to variation in the 70 erate the detuning means or variable condenser
adjustment of the condenser 3 by the manometer
3. As shown, the variable condenser 3 comprises
2 in response to a change in the rate of ?ow of
movable condenser plates 29 which are de?ected
fluid through the conduit I, the amplitude of the
relatively to stationary condenser plates 30 upon
undulating voltage produced at the output ter
angular de?ection of the gear sector 21. For pur
minals of discriminator I0 is correspondingly
poses of illustration, an increase in the rate of
I.
l
28
2,404,344
5
6
fluid flow through the pipe I may be assumed to
not constitute any part of the present invention,
cause the condenser plates 29 to rotate in a clock
wise direction to decrease the capacitance be
tween the condenser plates 29 and 30.
As shown in Fig. 1, the reversible electrical mo
tor I5 includes a stator 3| and a rotor 32 which
is provided with suitable conductor bars. A
power winding 33 and a control winding 34 are
and moreover, are completely illustrated and de
scribed in a copending application of Walter P.
Wills, Serial No. 421,173 ?led on December 1,
wrapped around suitable pole pieces
the stator 3|. Depending upon the
tion of the electrical current ?owing
control winding 34 with respect to
1941, and therefore, further description thereof
is not considered necessary herein.
As previously noted, the wiring diagram of the
electronic apparatus employed in the apparatus
embodiments of Fig. 1 and controlled jointly by
provided on
phase rela 10 the variable condenser or detuning means 3, and
through the
by the variable condenser or retuning means I‘!
the current
for selectively controlling the rotation and direc
?ow through the power winding, as is more fully
tion of rotation of the reversible motor I6, is
explained hereinafter, the rotor 32 is actuated for
more or less diagrammatically illustrated in
Fig. 2.
rotation in one direction or the other to cause
rotation of a pinion gear 35 in one direction or
Transmitter oscillator 4, as shown in Fig. 2, is
the other. The pinion gear 35 drives a gear 36
which is carried by a shaft 31 and is provided
with a projection 38 which abuts against the pin
an electron coupled oscillator and includes a
pentode tube 64 which may be of the commer
cially available type 6SJ7. The tube 64 includes
ion gear 35 for the purpose of limiting the extent 20 an anode 65, a suppressor grid 66, a screen grid
of rotation of the gear 38.
61, a control grid 68, a cathode 69 and a heater
Gear 38 carries a cable drum 39 which operates
?lament 10. The heater ?lament 70 is connected
a cable 40 strung over pulleys 4|, 42, 43 and 44.
to and receives energy from the secondary wind
The pulley 4| is carried by a lever 45 which is
ing ll of a transformer 12 having a line voltage
biased by a spring 46 in a clockwise direction
primary winding 13 and a high voltage secondary
about the pivot point 41 of the lever to maintain
winding 14 in addition to the low voltage sec
the cable 40 taut. The pulley 44 is arranged to
ondary winding 1|. Line voltage primary wind
operate the retuning means or variable condenser
ing 13 is connected to the alternating current
l‘! which, as shown in Fig. 1, comprises a variable
supply lines L’ and L". The supply lines L’ and
condenser having movable condenser plates 48 30 L" lead from a source of alternating current (not
adapted to be rotated with respect to relatively
shown) which supplies alternating current of rel
stationary condenser plates 49 upon rotation of
atively low frequency, for example, alternating
the pulley 44. The retuning means H, therefore,
current having a frequency of 60 cycles per sec
is adjusted in accordance with the angular posi
ond although it will be understood that other
tions assumed by the rotor 32 of the motor H5.
frequencies of alternation may be employed
The shaft 31 which carries the gear 36 may
equally as well. A switch 15 is provided at the
operate an indicating pointer (not shown) with
transmitter to control the application of electrical
respect to a suitably calibrated indicating scale
energy to the apparatus from the supply lines L’
(not shown). Also mounted on the shaft 31 is a
and L".
gear 58 which meshes with a gear sector 5| so
Control grid 68 of the pentode tube 64 is con~
that upon operation of the motor IS the gear
nected through a. resistance 16 to ground G and
sector 5| is rotated about its pivot 52. The gear
is also connected through a condenser 11 to one
sector 5| positions a pen arm 53 with respect to
terminal of a parallel circuit including the vari
a slowly rotating chart 54 for the purpose of
able condenser 3 in one branch and an inductance
providing a continuous record of the rate of ?uid
coil 18 in the other branch. The other terminal
?ow through the pipe I on the chart 54. Chart
of the parallel circuit is connected to ground G.
54 is driven at a constant, slow speed by a unidi
The inductance coil 18 is inductively coupled to a
rectional synchronous motor 54a which, as shown
coil 19 and together with condenser 3 provides for
in Fig. 2, is supplied with energizing alternating
high frequency operation of the oscillator. The
current from supply lines L’ and L". The gear
cathode 69 is connected through the inductance
sector 5| also operates an arm 55 which is ar
coil 19 to ground G. Screen grid 61 is con
ranged to adjust the position of the ?apper of a
nected through a condenser 80 to ground G and
pneumatic control device 56 forming part of the
is also connected through a resistance 8| to the
control apparatus |8a. The pneumatic control
positive terminal of a source of unidirectional
device 56 may be of the type shown and described
voltage created at the output terminals of ?lter
in Patent No. 2,125,081 which was issued to C. B.
82 by the transformer secondary winding 14 and
a recti?er designated at 83. The negative ter
Moore on July 26, 1938, and includes a nozzle
minal of the ?lter 82 is connected to ground G.
valve which is disposed in cooperative relation to
the ?apper and is connected by a bleed line 51 to
The recti?er 83 is of the half wave type and
a pilot valve 58 supplied with air under pres 60 it's circuit may be traced from one terminal of the
sure by a pipe 58. The pressures developed by
transformer secondary winding 14 to the anode of
the pilot valve 58 are transmitted through a pipe
a diode 84, and the cathode thereof to the posi
60 to the pneumatic control device 56 and by a
tive input terminal of the ?lter 82. The nega
pipe 6| to a pneumatic motor 62 which operates
tive input terminal of the ?lter 82 is connected
a valve 53 in the control means IQ for control
to the other terminal of the winding 14 and to
ling the rate of fluid flow through the pipe I.
ground G. The ?lament of the diode 84 is con
The pneumatic control apparatus including the
nected to and receives energizing current from
control device 53, the pilot valve 58, and the con
the transformer secondary winding 1|. Filter 82
trol means |9 may advantageously be utilized for
includes a pair of suitable condensers 85 and
the purpose of maintaining the rate of ?uid ?ow
a choke coil 86 for ?ltering the unidirectional
through the pipe I at a substantially constant
voltage applied to the screen grid 61 of the pentode
value.
tube 64. The ?lter 82 also includes a resistance 81
The details of construction of the reversible
and a condenser 88 for further ?ltering the uni~
motor IS, the indicating and recording apparatus
directional voltage output of the recti?er 83 for
l8, and the pneumatic control apparatus |8a do 75 providing a unidirectional voltage substan
2,404,344
7
tially free from ripple which is impressed on
the anode circuit of the pentode tube 64. As
shown, anode 65 is connected through a resist
ance 89 to the point of connection of the resist
ance 81 and condenser 88. The suppressor grid
66 is connected directly to ground G and serves
8
full wave recti?er designated at I05 and a ?lter
indicated at I06. The recti?er I05 includes a,
recti?er tube I01 having a pair of anodes and a
?lament type cathode having its terminals con
nected to the low voltage transformer secondary
Winding I00. One anode of the tube I01 is con
nected to one end terminal of the high voltage
the usual purpose of decreasing secondary emis
sion from the anode 65.
secondary winding WI and the other end termi
The oscillating circuit of the oscillator 4 in
nal of that high voltage winding is connected to
cludes the control grid circuit of which the par 10 the second anode of the tube I01. The ?lament
allel network including the detuning means
of tube I01 is connected to one input terminal
or condenser 3 forms a part and also includes
of the ?lter I06 while the other input terminal
the screen grid circuit which may be traced
of the ?lter is connected to the center tap of the
from the positive output terminal of the ?lter
82 through resistance 8I, screen grid 61, cathode
69, inductance coil 19 and ground G to the nega
tive terminal of the ?lter 82. These control grid
and screen grid circuits are inductively coupled
by the inductance coils 18 and 19 and provide
for high frequency operation over a range of
frequencies Which desirably may be in the region
of 4.3 megacycles per second.
In order that the high frequency oscillating
currents conducted through the screen grid cir
cuit may cause the voltage of the anode 65 to os
cillate at the same high frequency, the anode 65
of the oscillator tube is electron coupled to the
screen grid 61.
The high frequency oscillating
transformer secondary winding IOI. Filter I06,
as shown, includes suitably connected induct
ances I 08 and condensers I09. As will become
apparent as the description proceeds, the uni
directional voltage produced across the voltage
divider resistance I04 is also utilized to energize
the oscillator 1, the limiter 9, buffer II, ampli?er
I4, and the keyer I3 in addition to energizing the
screen and anode circuits of the ampli?er 9.
The anode circuit of the ampli?er 8 may be
traced from the potential point e on the voltage
divider I04 through a resistance IIO, a parallel
circuit including a resistance III in one branch,
a condenser I I2 in a second branch and a primary
Winding H3 of a transformer II4, having a sec
circuit for the anode 65 may be traced from the
ondary winding H5, in a third branch to the
positive terminal of the ?lter 82 comprising the 30 anode 9|, the cathode 95, the parallel connected
point of connection of resistance 81 and con
resistance I03 and condenser I 04 to ground G
denser 88 through resistance 89, anode 65, cath
and thereby to the potential point e on the voltage
ode 69 and inductance coil 19 to the grounded
divider. The point e on the voltage divider re
and negative terminal of the ?lter.
sistance I04 is so chosen as to be positive by a
While the anode or output circuit of the oscil 35 suitable amount with respect to the potential of
lator 4 is shown in Fig. 2 as being directly coupled
the point e.
by means of a condenser 90 to the transmission
Suppressor grid 92 is directly connected to the
line 5 and thereby to the input circuit of the re—
cathode 95 and is employed for the usual purpose
ceiver 6, it will be understood that stages of am
of minimizing secondary emission from the
pli?cation and isolation and an impedance 40 anode 9|.
matching network may be employed if desired.
The screen grid circuit of the ampli?er 8 may
The ampli?er 8 contained in the receiver 6
be traced from the point e on the voltage divider
comprises a radio frequency ampli?er and is em
resistance I04 through a resistance H6 and a
ployed to amplify the high frequency signal cur
radio
frequency choke coil M6’ to the screen 93,
rents conveyed to the receiver over the trans 45 cathode 95, and the parallel connected resistance
mission line 5. Speci?cally, the ampli?er 8 com
I03 and condenser I04 to the grounded potential
prises a pentode tube of the commercially avail
point e on the voltage divider resistance. The
able 6SJ7 type and includes an anode 91, a sup
screen 93 also is directly connected by a con
pressor grid 92, a screen grid 93, a control grid
denser II1 to ground G.
94, a cathode 95 and a heater ?lament 96. En
ergizing current is supplied to the heater ?lament
96 from the low voltage secondary winding 91
of a transformer 98 located in the receiver 6 and
having a line voltage primary winding 99, a low
voltage secondary winding I00, and a center
tapped high voltage secondary winding IOI in
addition to the low voltage secondary winding 91.
The input circuit of the ampli?er 8 comprises
The ampli?er high frequency signal currents
which ?ow through the output circuit of the
ampli?er 8 are conveyed by the transformer H4
to the input circuit of the limiter 9. As previously
noted, the limiter 9 may be of the type conven
tionally employed in frequency modulation broad
cast receivers. Speci?cally, limiter 9 may com
prise a pentode tube of the commercially avail
able 6SJ'1 type and includes an anode II8, a sup
a circuit interconnecting the control grid 94 and
the cathode 95 and may be traced from the con 60 pressor grid MS, a screen grid I20, a control grid
I2I, a cathode I22, and a heater ?lament I23.
trol grid 94 through a resistance I02 to ground
Energizing current is supplied to the heater ?la
G and through a parallel connected resistance
ment I23 from the low voltage transformer sec
I03 and a condenser I04 to the c .thode 95. As
ondary winding 91.
shown, the transmission line 5 is connected di
Anode voltage is supplied to the limiter 9
rectly to the control grid 94, the outer shield of 65
through a circuit which may be traced from the
the line 5 being connected to ground G. Thus
potential point 12 on the voltage divider I04
the high frequency signals generated by the oscil
through a resistance I 24 to a parallel network
lator 4 and transmitted to the receiver 6 by the
transmission line 5 are impressed on the input
including a condenser I25 in one branch and the
circuit of the ampli?er 8.
70 primary winding I26 of discriminator ID in the
other branch to the anode H8 and the cathode
Energizing voltage is supplied to the screen and
I22 to the grounded potential point e on the
anode circuits of the ampli?er 8 from a voltage
voltage divider I04.
divider resistance I04 which is provided with a
Energizing voltage is supplied to the screen I 20
number of voltage taps and across which a uni
directional voltage is maintained by means of a 75 from a portion of the voltage divider I04 shunted
‘r
I
28
2,404,344
by a resistance I21 which, as shown, is connected
between the potential points b and e on the
voltage divider. A contact I28 in engagement
with the resistance I 21 is provided for facilitat
ing adjustment of the voltage impressed on the
10
battery, in which case the recti?er 83 and ?lter 82
may be eliminated, Likewise, the energizing cur
rent source for the receiver 6 may be a battery
the use of which permits elimination of recti?er
I05 and ?lter I06. When a battery is employed
as the energizing source for receiver 6, however,
screen grid I20. The screen grid circuit may be
traced from the contact I28 to the screen grid
some additional means must be provided for cre
I 20 and the cathode I22 to the grounded poten
tial point e. Screen grid I20 is also directly con
ating the low frequency potential impressed on
the control grid circuit of the keyer I3 and also
nected to ground G by a condenser I29. The 10 for creating a voltage of the same low frequency
suppressor grid H9 is directly connected to the
for energizing the output circuits of the power
cathode I22.
ampli?er I5.
The control grid circuit for the keyer I3 com
prises two branches, one of which may be traced
energizing voltage to the screen grid I20. This 15 from the control grid I33 through a resistance
second circuit is so arranged as to apply a ?uc
I43 and the cathode biasing resistance I36 to
tuating or undulating voltage of relatively low
the cathode I34. The other vbranch comprises a
In accordance with the present invention, a
second circuit is also provided for applying an
frequency, compared to the frequency of the os
connection from one terminal of the transformer
cillating currents generated by oscillator 4, to the
secondary winding I31, to a tap provided on re
screen grid I20 for the purpose of amplitude 20 sistance I43, the other secondary winding ter
modulating the high frequency current output
minal being connected to ground G and through
from the limiter 9 at said relatively low fre
a condenser I44 to the point of connection of
quency. For this purpose the keyer I3, which
resistances I43 and I36. As those skilled in the
may comprise a commercially available type
art will understand the impression on the con
trol grid circuit of pentode tube I3 of an alter
6SJ7 tube, is provided.
The keyer I3 includes an anode I30, a suppres
sor grid I3I, a screen grid I32, a control grid I33,
and L" causes the potential of the anode I30
a cathode I34, and a heater ?lament I35. Ener
to undulate with an approximately square wave
nating voltage derived from the supply lines L'
gizing current is supplied the heater ?lament I35
form at the frequency of the voltage of the said
from the transformer secondary winding 91. The 30 supply lines, and hence, causes the potential of
suppressor grid I3I is directly connected to the
the screen grid I20 of limiter 9 to similarly un
cathode I34. Anode voltage is supplied the keyer
dulate. In this manner, the high frequency cur
I3 from the voltage divider resistance I04 through
rent output of the limiter 9 is amplitude modu
a circuit which may be traced from the contact
lated at the relatively low frequency of the volt
I28 in engagement with resistance I21 to the 35 age supplied by supply lines L’ and L". Thus,
anode I30, cathode I34 and a cathode biasing re
when the frequency of alternation of the voltage
sistance I30 to the negative terminal I of the
of supply lines L’ and L" is 60 cycles per second,
voltage divider resistance I04. As shown, the
the high frequency current output of the limiter
anode I30 is directly connected to the screen grid
9 is amplitude modulated at the frequency of
I20 of the limiter tube 9. Screen grid voltage is 40 60 cycles per second.
supplied the keyer I3 through a circuit which
For the purposes of the present invention, the
may be traced from the potential point at on the
modulating or keying of the high frequency cur
voltage divider resistance to the screen grid I32,
rents at the frequency of the low frequency cur
rent need not be 100% amplitude modulation in
cathode I34, and the cathode biasing resistance
I35 to the negative terminal y of the voltage di 45 asmuch as the embodiments of the invention dis
closed Will operate satisfactorily if the modula
vider resistance.
tion is less than 100%. In order to attain the
An alternating voltage of relatively low fre
most efficient operation, however, it is desirable
quency is impressed on the control grid I33 of
for the high frequency current output of the lim
the keyer'tube I3 from the secondary winding I31
of a. transformer I38 also having a line voltage 50 iter 9 to be substantially 100% modulated or
keyed With a square wave. By so modulating or
primary winding I39, a low voltage secondary
keying the output of the limiter 9, the greatest
winding I40, and a center tapped high voltage
possible output voltage of one phase or of op
secondary winding MI. The line voltage primary
posite phase is produced across the output ter
winding I39 has its terminals connected to a
source of alternating current which may be of. 65 minals of discriminator I0 for a given change in
adjustment of the detuning condenser 3.
the same frequency as that supplied by the supply
With respect to its limiting function, the lim
lines L’ and L” at the transmitter 4. For con
iter 9 is essentially an ampli?er stage which sat
venience of illustration the primary winding I39
urates at a predetermined level depending upon
has been shown as being connected through a
the circuit constants, and is employed for the
switch I42 to the supply lines L’ and L". When
purpose of limiting the amplitude of the high
the transmitter 4 and the receiver 6 are located at
frequency signal currents in order to make the
a great distance from each other, however, it will
amplitude of the modulated high frequency sig
be evident that the supply lines L’ and L" at the
nal currents impressed on the input circuit of
transmitter and the supply lines L’ and L" at 65 the discriminator I0 independent of variations
the receiver will probably not be supplied from
in the amplitude of the high frequency signal
the same source. This circumstance does not in
currents received by the receiver 6 over the trans
terfere with or detract from the operation of the
mission line 5, and thereby, independent of var
apparatus of my invention, however, inasmuch as
iations in the transmission line characteristics
it is not necessary to the operation of the inven 70 and of variations in the energizing voltage sup
tion that the receiver and the transmitter be
ply sources.
energized from the same source of alternating
The control grid circuit of the limiter 9 in
current. Moreover, the energizing current source
cludes a resistance I45 connected between the
for the transmitter ‘4 need not be a source of alter
control grid I2| and the cathode I 22 and also
nating current, but if desired, may comprise a 75 includes a network shunting the resistance I45
r
u
2,404,344
11
12
comprising a condenser I46 in series with a par
winding I 26 to the same frequency as that to
allel network consisting of the transformer sec
ondary winding H5 in one branch, a condenser
I41 in a second branch, and a resistance I48 in
a third branch. The values of these elements in
which the split secondary winding is tuned.
When the frequency of the modulated high fre
quency signal currents impressed on the trans
former primary winding I26 is 4.3 megacycles, as
the input circuit are so chosen in relation to
suming that both the primary winding I26 and
the voltages impressed on the screen grid and
the split secondary winding are tuned to this fre
anode circuits that the limiter 9 saturates when
quency, the voltages in the split secondary Wind
the high frequency signal currents created in the
ing sections I53 and I54 and appearing across the
transformer secondary winding H5 reach a de 10 terminals of the split secondary winding will be
sired maximum value. Further increases in the
90° out of phase with the applied primary voltage.
magnitude of the high frequency signal currents
This voltage relationship is shown graphically in
are then ineffective to produce any change in
Fig. 3 wherein the vector E126 represents the volt
the magnitude of the modulated high frequency
age applied to the primary winding I26 and the
signal currents which flow through the primary 15 vectors E153 and E154 represent the voltages ap
winding I26 of the discriminator I0, which pri
pearing across the split secondary winding sec
mary winding, as shown and previously noted,
tions I53 and I54, respectively. The phenomena
is connected in the anode circuit of limiter 9.
giving rise to the 90° phase shift between the sec
The frequency discriminator I0 includes a
ondary and primary voltages is one known in the
transformer I49 and a pair of diode racti?ers I50 20 art and needs no explanation herein.
and I5I which desirably may be contained within
The secondary winding sections I53 and I54 are
a single envelope generally designated at I52.
so wound on the transformer I49 that the voltage
The transformer I49 is comprised of the primary
appearing across the winding I54 is 180° out of
winding I26 and a split secondary winding, one
phase with the voltage appearing across the
section of which has been designated I 53 and the
winding I53, as is shown in Fig. 3. The voltage
other I54. The center tap of the split second
appearing across the secondary winding I54 is
ary winding, comprising the point of connection
impressed on the circuit including the diode rec
of the adjacent ends of the secondary winding
ti?er I50 and resistance I51 while the voltage ap
sections I53 and I54, is connected through a
pearing across the secondary winding I53 is im
blocking condenser I 55 to the anode I I8 of the
pressed on the circuit including diode I5I and re
limiter 9, and is also connected to the upper ter
sistance I58. Superimposed on these voltages im
minal of the transformer primary winding I26.
pressed on the diodes I50 and I5I is the voltage
That center tap is also connected through a
developed across the primary winding I26. The
choke coil or inductance I56 to the point of en
primary voltage is superimposed on the diodes
gagement of a pair of resistances I51 and I 58. 35 I50 and I5I since the upper terminal of the pri
The usable output voltage from the frequency
mary winding I26 is connected through the
discriminator I0 is obtained across the resist
blocking condenser I55 to the point of engage
ances I51 and I58 and appears between the dis
ment of the secondary winding‘ sections I53 and
criminator output terminals I69 and I10.
I54. Thus, the primary voltage is impressed in
The diode recti?ers I50 and I 5I may be con
tained within a single tube such as the commer_
series with the voltage produced across the sec
cially available type 6H6. Speci?cally, the di
odes each include anode, cathode and heater ?la
ment elements indicated by the respective nu
merals I59, I60 and I6I in the diode I50 and by
the respective numerals I62, I63 and I64 in the
diode I5I. Each of the heater ?laments I6I and
ondary winding section I54 on the circuit includ
ing diode I50 and resistance I51, and the primary
voltage is impressed in series with the voltage
produced across the secondary winding I53 on
the circuit including diode I5I and resistance I58.
The resultant voltage impressed on the circuit
including the diode I50 is the vector sum of the
I64 are connected to and receive energizing cur
primary voltage E126 and the secondary voltage
rent from the transformer secondary winding 91.
E154, represented in Fig. 3 by the vector Er. The
vector E’r represents the resultant voltage im
pressed on the circuit including diode I5I. In
The cathode I60 of diode I50 is connected through
the resistance I51 and the inductance I56 to
each case the resultant voltage on each diode is
the center tap on the split secondary winding,
the vector sum of two voltages which are in phase
and the cathode I63 of the diode I5I is also so
connected through the resistance I 58 and the in 55 quadrature at resonance. The secondary volt
age applied to the diode I50, however, leads the
ductance I56. Anode I59 is connected to the
primary voltage by 90° while the secondary volt
end terminal of the split secondary winding sec
age applied to the diode I5I lags by 90° the pri
tion I54 while anode I62 is connected to the end
mary voltage. The absolute values of the primary
terminal of the secondary winding section I53.
A condenser I65 is provided in parallel to the 60 and secondary voltages in relation to each other
are not critical and may be selected as desired.
split secondary winding, as shown, for tuning the
The 90° phase relationship between the voltage
latter to a desired frequency in the region of 4.3
applied
to the primary winding I26 and the volt
megacycles, and if desired, may be $0 chosen as
".ges appearing across the secondary winding
to tune the split secondary winding precisely to
‘sections I 53 and I54 exists only when the ap
that frequency value. Each of the resistances 65 plied frequency to the primary winding I26 is the
I51 and I58 are shunted by a respective condenser
value to which both the primary winding and the
I66 and I61. The blocking condenser I55 and
split secondary winding are resonant. Upon de
the condensers I66 and I61 are so selected as
parture of the applied frequency from this value,
to present low impedance to the high frequency
the voltage appearing across the secondary wind
oscillating currents ?owing through them. The 70 ing sections I53 and I54 also departs from the 90°
condenser I25 and the transformer primary wind
phase relationship with the primary winding ap
ing I26 are so selected as to provide high im
plied voltage, as is indicated by the vectors E’isa
pedance in order to produce a large output signal
and E354 in Fig.3. For example, upon increase
voltage from the discriminator. Preferably, the
in the applied frequency from the value to which
condenser I 25 is so chosen as to tune the primary 75 the secondary winding is resonant, the phase dis
28
-
2,404,344
13
14
placement between the voltage appealing across
drop across the resistance I51 being the greater,
the secondary Winding section I54 and the ap
occurring upon an increase in the applied fre
plied primary voltage decreases toward zero,
quency. The portion of curve E0 to the left of
while the phase displacement between the voltage
the y—y axis represents the difference in magni
appearing across the secondary winding section CI tudes of the voltage drops across the resistances
153 and the primary voltage increases toward
I51 and I58, that across the resistance I58 being
180°. Upon decrease in the applied frequency the
the greater and occurring upon a decrease in the
applied frequency.
converse is true. That is to say, the phase dis
placement between the vectors E126 and E154 in
Since the high frequency signal currents ap
Fig. 3 increases toward 180° while the displace 10 plied to the primary winding I28 of the discrim
ment between the vectors E126 and E153 decreases
inator I0 are modulated at the relatively low fre
toward zero. In other words, when the applied
quency of the voltage supplied by the supply lines
frequency deviates from the value to which the
L’ and L", the voltage drops which are produced
primary and secondary windings are resonant,
across the resistances I51 and I58 will be corre
the voltage appearing across one of the secondary
spondingly modulated at that low frequency. In
winding sections I53 and I54 will be more nearly
other words, when the high frequency current
in phase with the primary voltage while the volt
age across the other secondary winding section
will be more nearly 180° out of phase with the
primary voltage.
When the applied frequency to the primary
winding I28 deviates slightly from the value to
which the secondary Winding is tuned, the re
sultant voltage applied to one of the diodes I50
output of the limiter 9 is substantially 100%
modulated, the voltage drops across resistances
I51 and I58 will be produced thereacross only
20
during the regularly recurring intervals when
high frequency currents ?ow from the output cir
cuit of the limiter 9 to the discriminator I0.
During the intervals when no high frequency
currents ?ow from the limiter 9 to the discrimi
or I5I will decrease, as indicated by the vector 25 nator I0, no voltage difference is created across
E'ar while the resultant voltage applied to the
either of the resistances I51 and I58. Accord
ingly, there are two conditions in which the re
other diode will increase as shown by the vector
Ear. Upon greater deviation in the applied fre
sultant of the voltages across resistances I51 and
I58 and impressed across the output terminals
quency in the same direction from the value to
I89 and I10 of the discriminator I0 is zero. The
which the secondary winding is resonant, the re
?rst condition is that existing when no high fre
sultant voltage applied to the second-mentioned
quency currents are applied to the primary wind
diode will increase to a maximum value, and upon
which the resultant voltage applied to the diode
I50 changes upon variation in the applied fre
ing I28. The second condition is that occurring
when the frequency of the high frequency cur
rents applied to the primary winding I26 is the
value to which the secondary winding of the dis
criminator is tuned.
quency and the curve e’r represents the manner
In the arrangement disclosed, high frequency
still greater frequency deviation, also begin to de
crease, as may be seen by reference to Fig. 4
wherein the curve er represents the manner in
currents are applied to the discriminator I0 only
in which the resultant voltage applied to the diode
during alternate half cycles of the alternating
I5I simultaneously changes.
voltage derived from the supply lines L’ and L".
As illustrated in Fig. 4, the resultant voltage er
Consequently, when the frequency of the high
applied to the diode I50 increases initially, as the
frequency currents applied to the discriminator
applied frequency increases from the value to
I0 is the value, 4.3 megacycles, to which the sec
which the secondary winding is resonant, until
a maximum value is attained following which it 45 ondary Winding is tuned, no voltage drop is cre
ated between the discriminator output terminals
again decreases as the applied frequency is
I89 and I10 during the half cycles, hereafter
changed further in the same direction. Concur
termed the operative half cycles, when high fre
rently, the resultant voltage applied to the other
quency currents flow from the limiter 9 to the
diode I5I will decrease and continue to decrease
discriminator I0. During the other half cycles
gradually as the applied frequency further devi
of the alternating supply voltage, no high fre
ates from the resonant Value. As a result of this
quency currents are applied to the discriminator
action, the voltage drop produced across the re
primary winding I28 and in this case also no volt
sistance I51 is increased, while that across the
age drop appears between the discriminator out
resistance I58 is decreased.
Upon deviation in the applied frequency to the 55 put terminals I69 and I10. As a consequence,
when the frequency of the high frequency cur
primary winding I28 in the opposite direction
rents supplied to the primary winding I28 cor
from the value at which the secondary winding
responds to the value to which the discriminator
is resonant, the resultant voltage applied to the
I0 is tuned, the potential of the terminal I89 is
diode I50 will decrease while the resultant volt
age contemporaneously applied to the diode I51 60 the same as that of the terminal I10.
When the frequency of the high frequency cur
will increase to a maximum value, following, the
rents applied to the discriminator primary wind
attainment 01 which it will also begin to decrease.
ing I28 increases above 4.3 megacycles per sec
As a result c‘ this action, the voltage drop pro
ond, the value to which the discriminator I0 is
duced across the resistance I58 will be increased
while that produced across resistance I51 will be 65 resonant. a resultant potential drop of the polar
ity rendering the terminal I89 positive with re
decreased.
spect to the terminal I10 is created across the re
The manner in which the voltage drops across
sistances I51 and I58 during the operative half
the resistances I51 and I58 change with variation
in the applied frequency is illustrated in Fig. 4
cycles of the alternating voltage supplied by the
by curve E0. At the point of intersection of the 70 supply lines L’ and L". During the other half
cycles no high frequency currents are supplied to
curve E0 with the x—a: axis the voltage drops
the discriminator I0, and therefore, the poten
across the resistances I51 and I58 are equal. The
tials at the terminals I89 and I10 will be identical.
portion of the curve E0 to the right of the y—y
As a result, an undulating or pulsating voltage is
axis represents the difference in voltage drops
across the resistances I51 and I58, the voltage 75 created between the terminals I89 and I10 upon
I
I
|
2,404,344
15
16
increase in the frequency of oscillation of the
I3, and the balanced discriminator I2 to which
high frequency currents applied to the discrimi
reference has previously been made.
nator I0. This ?uctuating voltage will be of one
The oscillator 1 may be and has been shown
phase or of opposite phase with respect to the
as being identical to the oscillator 4 and includes
voltage of the supply lines L' and L”, and for
a pentode tube I1I which may be of the com
purposes of explanation, may be assumed to be in
mercially available type 6SJ7. The tube I1I in
phase with the voltage of the supply lines L’ and
cludes an anode I12, a suppressor grid I13, 3
L", as indicated in Fig. 5, wherein the curve ES
screen grid I14, a control grid I15, a cathode I16
represents the supply line voltage and the curve
and a heater ?lament I11. The heater ?lament
El represents the output voltage of the discrimi 10 I11 is connected to and receives energizing cur
nator I0 appearing between the terminals I69
rent from the transformer secondary winding 91.
and I10 upon an increase in the applied frequency
Anode voltage is supplied to the oscillator 1 from
to the discriminator.
the voltage divider resistance I04 through a cir
Upon decrease in the frequency of oscillation of
cuit which may be traced from the potential
the high frequency currents applied to the dis 15 point a on the divider I04 through resistances I18
criminator I0, an undulating or pulsating voltage
and I 19 to the anode I 12, the cathode I16 and
of opposite phase is produced between the termi
the inductance coil I80 to the grounded poten
nals I69 and I10. This result is brought about
tial point e on the divider I04. A condenser I8I
by virtue of the fact that during the operative
connected between ground G and the point of
half cycles of the voltage of the supply lines L’ 20 engagement of resistances I18 and I19 is employed
and L", the voltage drop across the resistance I58
to provide additional ?ltering of the voltage ap
will be greater than that across the resistance
plied to the anode I12. The suppressor grid I13
I51, thus rendering the potential of the terminal
is directly connected to ground G.
'
I10 positive with respect to that of the terminal
Screeen
grid
voltage
is
supplied
to
the
oscil
I69. During the other half cycles no high fre
lator tube I 1| from the divider resistance I04
quency currents are impressed on the discrimi
through a circuit which may be traced from the
nator I0, and consequently, the potentials of the
point a through a resistance I82 to the screen
terminals I69 and I10 are identical. According
grid I14, the cathode I16 and the inductance coil
1y. an undulating or pulsating voltage is produced
I80 to the grounded potential point e.
between the terminals I69 and I10 which is 180° 30
The control grid I15 is connected through a
out of phase with the voltage of the supply lines
resistance I83 to ground G and through a con
L’ and L”.. This voltage output is represented
denser I84 to one terminal of a parallel circuit,
by the curve Ed in Fig. 5.
the other terminal of which is connected to
From the foregoing explanation it will be clear
that the potentials at the discriminator output 35 ground, including the retuning means or variable
condenser I1 in one branch and an inductance
terminals I69 and I10 are identical when the
coil I 85 in the second branch. The inductance
frequency of oscillation of the high frequency
coil I85 is inductively coupled to the inductance
currents applied to the discriminator I0 is the
coil I80. If desired a trimming condenser, not
value to which the discriminator is resonant, and
that upon deviation in the frequency of the ap 40 shown, may be connected in parallel with the
condenser I1 and the inductance coil I85 for
plied high frequency to the discriminator in one
providing a ?ne adjustment of the zero setting
direction or the other from the resonant value,
of the instrument pen and pointer.
a pulsating voltage of one phase or of opposite
The oscillating circuit of the oscillator 1 in
phase with respect to the voltage of the supply
cludes the control grid circuit of which the par
lines L’ and L" is created between the terminals 45 allel circuit including the retuning means I1
I69 and I10. It will be clear also that the am
forms a part and also includes the screen grid
plitude of ?uctuation of the undulating voltage
circuit. These circuits are inductively coupled by
so produced between the terminals I69 and I10
the inductance coils I80 and I85 and provide for
is dependent upon the extent of deviation of the
high frequency operation over a range of fre
applied frequency from the value to which the
quencies in the region of 4.3 megacycles per sec
discriminator is tuned, as will be apparent upon
ond. The anode I12 of the oscillator pentode tube
reference to the E0 in Fig. 4. Inasmuch as the
I1I is electron coupled to the screen grid I14
high frequency signal currents generated by the
50 that the high frequency oscillating currents
oscillator 4 and transmitted to the receiver 6 are
?owing through the screen grid circuit may cause
keyed by the keyer I3 with a square wave form 55 the voltage of the anode I12 to oscillate at the
at the frequency of the voltage supplied by the
same high frequency. The screen grid I14 is
lines L’ and L", the undulating voltage produced
connected to ground through a condenser I14’.
between the terminals I69 and I10 is substan
As shown, the anode 0r output circuit of the
tially a square wave form.
oscillator 1 is coupled by means of a condenser
60
Those skilled in the art will recognize that
I88 to the input or control grid circuit of the
the invention in its practical application is not
buffer I I. The buffer I I comprises a pentode tube
restricted to the use of a frequency discriminator
I81 of the type 6SJ7 including an anode I88, a
ID of the type disclosed and that other types,
suppressor grid I89, a screen grid I90, a control
particularly those conventionally employed for
grid I9I, a cathode I92 and a heater ?lament I93.
automatic frequency control and frequency modu
The heater ?lament I93 is connected to and re
lation detection in radio broadcast receivers may
ceives energizing current from the transformer
be employed equally as well.
secondary winding 91.
For the purpose of generating a second undu
Anode voltage is supplied to the tube I81 from
lating or pulsating voltage opposite in phase but 70 the voltage divider resistance I04 through a cir
of the same frequency and of substantially the
cuit which may be traced from the point b on
same wave form as that created between the dis
the divider resistance through a resistance I94,
criminator output terminals I69 and I10, there is
the primary winding I95 of the frequency dis
also provided in the receiver 6, the oscillator ‘I,
criminator I2, the anode I88, cathode I92 and a
the buffer II arranged to be keyed by the keyer 75 parallel connected resistance I96 and condenser
y
I
28
2,404,344
17
I91 to the grounded potential point e on the di
vider resistance. The transformer primary wind
ing I95 is shunted by a condenser I98.
Screen grid voltage is supplied the tube I81
from a portion of the voltage divider I04 which
is shunted by a resistance I99 which, as shown,
is connected between the potential points b and
e on the divider. A contact 200 slidable along
the resistance I99 is provided for the adjustment
of the voltage impressed on the screen grid I90, 10
and is connected to ground through a condenser
200’. The screen grid circuit may be traced from
the contact 200 through an inductance or choke
18
transformer primary winding I95. The center
tap of the split secondary winding is also con
nected through a. choke coil or inductance 209 to
the point of engagement of a pair of resistances
2I0 and 2I I, The usable output voltage of the
discriminator I 2 is obtained across the resistances
2 I0 and 2| I and appears between the output ter
minals designated at 2I2 and 2I3.
As shown,
the resistance 2 I0 is shunted by a condenser 2I4
and the resistance 2 II is shunted by a condenser
2I5.
The diode recti?ers 203 and 204 may be con
tained within a single tube such as the com
coil 20| to the screen grid I90, the cathode I92,
mercially available type 6H6, and each include
and the parallel connected resistance I96 and 15 anode, cathode and heater ?lament elements
condenser I91 to the grounded potential point e.
which have been designated by the respective
The suppressor grid I89 is connected directly
reference numbers ZIB, 2I1 and 2I8 in the diode
to the cathode I92. The screen grid I90 is con
203 and by the respective reference numbers 2 I 9,
nected to ground through a condenser I90’.
220 and 22I in the diode 204. Both of the heater
The control grid I9I is connected by a resist 20 ?laments 2I8 and 22I are connected to and re
ance 202a to ground G and is also connected
ceive energizing current from the transformer
through the condenser I86 to the anode I12 of
secondary winding 91. The cathode 2I1 of the
the oscillator tube I1I.
diode 203 is connected through the resistance 2I0
For the purpose of amplitude modulating the
high frequency current output from the buffer I I
at the relatively low frequency of the voltage
supplied by the supply lines L' and L", a second
circuit including the keyer tube I3 is provided
for applying an undulating voltage of that rela—
tively low frequency to the screen grid I90. This 30
and the inductance 209 to the center tap on the
Split secondary Winding, and the cathode 220 is
also so connected through the resistance 2“ and
the inductance 209. Anode 2I6 is connected to
the end terminal of the split secondary winding
section 206 and the anode 2I9 is connected to
the end terminal of the winding section 201. A
condenser 222 is provided in parallel to the split
second circuit may be traced from the screen grid
I90 of the buffer tube I91 through the choke
secondary winding for tuning the latter to the
coil 20I to the anode I30 of the keyer tube I3,
same frequency as that to which the split sec
_ the cathode I34, the biasing resistance I36, con
denser I44 to ground G, and through the parallel
connected resistance I96 and condenser I91 to
the cathode I92 of the buffer tube I81. As pre
viously explained, the potential of the anode I30
ondary winding of the discriminator I0 is tuned.
The blocking condenser 208 and the condensers
2 l4 and 2I5 are so selected as to present low im
pedance to the high frequency oscillating cur
rents ?owing through them. The condenser I98
and the transformer secondary Winding I95 are
of the keyer I3 undulates or ?uctuates with a
square wave characteristic at the relatively low 40 so selected as to provide high impedance in order
frequency of the voltage of the supply lines L’
to create a large output signal voltage from the
and L", and accordingly, causes the potential of
discriminator. Preferably the condenser I98 is
the screen grid I90 of the buffer tube I81 to cor
so chosen as to tune the primary winding I95
to the same frequency as that to which the split
respondingly undulate or ?utuate. Consequent
ly, the high frequency current output of the
buffer stage II is amplitude modulated at the
relatively low frequency of the supply lines L’
and L". Since the high frequency current out
put of the buffer stage is amplitude modulated
by the keyer tube I3 which is also employed to
amplitude modulate the high frequency current
output of the limiter 9, the wave form of the
modulation envelope of the output current from
the buffer II will be substantially identical to
the modulation envelope of the output current
appears across the discriminator output termi
nals 2I2 and 2I3. Upon deviation of the applied
frequency in one direction from that frequency
from the limiter 9.
value, however, an undulating voltage having the
secondary winding is tuned.
The operation of the frequency discriminator
I2, as previously noted, is the same as that of the
frequency discriminator I0. Thus, when the fre
quency of the modulated high frequency currents
impressed on the input circuit of the frequency
discriminator I2 is the value to which the fre
quency discriminator is tuned no output voltage
The modulated high frequency currents ?ow
same frequency as the voltage of the supply lines
ing from the output circuit of the buffer II are
L’ and L" and of one phase with respect to the
impressed on the frequency discriminator I2
voltage of the supply lines L’ and L" will appear
which may be identical in operation and in con 60 between the output terminals 2I2 and 2I3, while
struction to the frequency discriminator I0.
Speci?cally, the frequency discriminator I2 in
cludes a transformer 202 and a pair of diode rec
ti?ers 203 and 204 which may be contained with
upon deviation of the applied frequency in the .
opposite direction an undulating voltage of the
same frequency but of opposite *hase Will appear
between those output terminals.
in a single envelope generally designated at 205.
In order to create an undulating or pulsating
The transformer 202 includes the primary wind
voltage which may be employed to control the
I95 and a split secondary winding, one section of
selective energization of the reversible electrical
which has been designated by the reference nu
motor I9 for rotation in one direction or the other
meral 206 and the other by the reference nu
whenever the output signal voltages of the dis
meral 201. The center tap of the split second
criminators I0 and I2 are of unequal amplitude,
ary winding comprising the point of connection
the mixing ampli?er I4 comprising two parallel
of the adjacent ends of the winding sections 206
connected ampli?er triode sections 223 and 224
and 201 is connected through a blocking con
is provided. As shown, the undulating output
denser 208 to the anode I98 of the buffer II and
voltage of the discriminator I0 is impressed on
is' also connected to the upper terminal of the 75 the input circuit of the triode 223 while the un
1
I
‘2,404,344
19
dulating output voltage of the discriminator I2 is
20
identical and symmetrical frequency discrimina
impressed on the input circuit of the triode 224.
tors I0 and I2 tuned to the same frequency, bal
As will become apparent as the description pro
ance is reached in the contemplated operation of
ceeds, the phase of the output voltage obtained
the arrangement shown when one oscillator fre
from the mixing ampli?er l4 depends on the rela Cl quency is higher than the discriminator balanced
tive magnitudes of the two input signal voltages
frequency by the same amount that the other
and the amplitude of the mixing ampli?er output
oscillator frequency is lower.
signal voltage depends upon the difference be
If it is desired that both oscillators have the
tween the amplitudes of the input signal voltages.
same frequency of oscillation at the balanced con
The triodes 223 and 224 may be contained with 10 dition, the two high frequency signal currents
in a single envelope and for example may each
may be keyed 180° out of phase. Such operation
comprise one half of a commercially available
can be readily accomplished by providing indi
type 7F? tube. The section 223 includes an anode
vidual keyers for the limiter 9 and for the buffer
225, a control grid 226, a cathode 221, and a heat
II and by impressing a 60 cycle per second al
er ?lament 228, while the section 224 includes an 15 ternating voltage on the control grid of one keyer
anode 229, a control grid 230, a cathode 23I and
displaced 180° in phase with respect to that im
a heater ?lament 232. Energizing current is sup
pressed on the control grid of the other keyer.
plied to each of the heater ?laments 228 and 232
Alternatively, the two high frequency signal cur
from the transformer secondary winding 91.
rents may be keyed in phase, as in the arrange
The anode circuits of the tube sections 222 and 20 ment of Fig. 2 disclosed, and the undulating out
223, as shown, are connected in parallel and are
put voltage of the frequency discriminator I2 may
supplied with voltage from the voltage divider re
be reversed, rendering it 180° out of phase with
sistance I04 through a circuit which may be
the undulating output voltage of discriminator
traced from the potential point a through a re
I0, by reversing the cathode connections of the
sistance 233 to the anodes 225 and 229, and the
diodes 203 and 294 to the resistances 2I0 and 2I I,
cathodes 227 and 23I to the grounded potential
that is by connecting cathode 2I1 to the lower
point e on the voltage divider. The control grid
end of resistance 2H and by connecting cathode
226 of the tube section 223 is connected to the
220 to the upper end of resistance 2 I 0.
output terminal I 59 of the frequency discrimina
The power ampli?er I5 comprises a twin triode
tor I0 and the output terminal I ‘I0 thereof is con 30 tube such as the type 7N7 tube. One triode in
nected to the cathode 227. The control grid 230
cludes an anode 235. a control grid 236, a cathode
of the tube section 224 is connected to the output
231 and a heater ?lament 238, while the other
terminal 2I2 of the frequency discriminator I2
triode includes an anode 239, a control grid 240,
while the output terminal 2I3 is connected to
a cathode 24I, and a heater ?lament 242. The
the cathode 23!. Therefore, the output voltage
heater ?laments 238 and 242 are connected to,
of the frequency discriminator I0 is impressed
on the control grid or input circuit of the tube
section 223 while the output voltage of the fre
and receive energizing voltage from, the winding
I 40 of the transformer I38. The control grids 236
When the apparatus disclosed is in its balanced
or stabilized condition the undulating signal volt
age impressed on the input circuit of the tube
section 223 from the frequency discriminator I0
in turn, is connected in series with the condenser
234 from the anodes 225 and 229 of the mixing
ampli?er I4 to ground G. The condenser 234 is
provided for impressing the ?uctuating or un
dulating components of voltage produced across
and 240 are directly connected to each other and
quency discriminator I2 is impressed on the con
to a contact 243 in engagement with and adjust
trol grid or input circuit of the tube section 224. 40 able along the length of a resistance 244, which,
is of the same amplitude and wave form but is -
opposite in phase to the undulating voltage im
pressed on the input circuit of the tube section
224 from the frequency discriminator I2. As
those skilled in the art will understand, with such
undulating signal voltages impressed on the input '
‘circuits of the mixing ampli?er I4 a substantial
ly steady unidirectional voltage drop will be pro
the resistance 233 on the input circuit of the
power ampli?er I5 while preventing the direct
current component of the current flow through
the anode circuits of the mixing ampli?er l4
from being impressed on said input circuit. The
output voltage from the mixing ampli?er I4,
therefore, is impressed simultaneously and
duced across the common load resistance 233.
equally on both of the power ampli?er control
This steady voltage is ineffective to cause rotation
grids 236 and 240. The adjustable resistance 244
of the reversible motor I6. Upon deviation in 55 is provided to facilitate adjustment in the gain of
the amplitude of the undulating voltage im
the power ampli?er I5.
pressed on the input circuit of the tube section
Anode voltage is supplied to the triodes of the
223 from the frequency discriminator I0 from the
power ampli?er I5 from the split secondary wind
balanced value, an undulating voltage of the same
ing I4I on the transformer I38. To this end the
frequency as that of the voltage of supply lines 60 anode 235 is connected to the left end terminal
L’ and L" and of one phase or of opposite phase
of the winding I M while the anode 239 is con
depending upon the direction of deviation will
nected to the right end terminal of that winding.
be produced across the load resistance 233 in the
The cathodes 231 and MI are connected together
output circuit of the mixing ampli?er I4 and will
and through a biasing resistance 245 to ground G.
be impressed on the input circuit of the power
The center tap on the split secondary winding
ampli?er I5. When said undulating voltage is
MI is connected through the control winding 34
of one phase relatively to the voltage of the sup
of the motor I6 to ground G and through the
ply lines L’ and L”, the motor I6 will be actu
biasing resistance 245 to the cathodes 231 and
MI.
ated for rotation in one direction while it will be
actuated for rotation in the opposite direction
As is illustrated in Fig. 1, the reversible motor
when the said undulating voltage is of opposite
I6 is provided with a stator 3I having four pole
phase.
pieces which are physically spaced apart by 90°
In the arrangement disclosed, the received and
and also includes a squirrel cage rotor 32 hav
the locally generated high frequency signal cur
ing interconnected conductor bars. It will be
rents are keyed in phase by the keyer I3. For 75 evident that more than four pole pieces may be
1
J
IUItCil e 335351113
28
2,404,844
21
22
provided on the motor I6, if desired. For ex
ample, in a commercially available embodiment
of the motor illustrated, the stator 3| is provided
with eight pole pieces. The power winding 33 is
wrapped around two of the opposite pole pieces
of the stator 3| and the control winding 34 is
rent ?ow through the power winding, and be
cause of the decrease in apparent inductance, the
voltage across the power winding also decreases.
This produces further reduction of power loss in
wrapped around the remaining two opposite pole
the power windings.
As a result there is a sub
stantial reduction of heating of the power wind
ings when the rotor 32 is at rest.
pieces. When only the power winding 33 is en
Power is supplied to the control winding 34
ergized, the rotor 32 is not urged to rotation in
from the splitsecondary winding I4I of the trans
either direction and remains stationary, When 10 former I38 through the anode circuits of the twin
the control winding 34 is energized and the volt
triodes of the power ampli?er I5 through the
age and current through it lead the voltage and
circuits previously traced. A condenser 24‘! is
current, respectively, in the power winding 33,
connected in parallel with the control winding
the rotor 32 is actuated for rotation in one direc
34 and is so selected as to provide a parallel
tion, for example, in a clockwise direction. 15 resonant circuit during both the stalled and run
When the voltage and current in the control
ning conditions of the motor. This parallel reso
winding 34 lag the voltage and current, respec
nant circuit presents a relatively high external
tively, in the power winding 33, the rotor 32 ro
impedance and a relatively low internal im
tates in the opposite direction.
pedance. The relatively high external impedance
The motor I6 is preferably so constructed that 20 of the parallel resonant circuit matches the im
the control winding 34 and parallel connected
pedance of the anode circuit of the power ampli
condenser 24‘! has a high impedance to match the
?er triodes and, therefore, provides for optimum
impedance of the anode circuits of the power
ampli?er I5 when the rotor 32 is rotating at full
conditions of operation. The relatively low in
ternal circuit impedance of the control winding
speed. By providing a power winding 33 having
25 34 and the condenser 24'! approximates the ac
high impedance, increased efficiency of opera
tion is obtained. Preferably, the control and
tual resistance of the control winding 34, and
since this is relatively low, the impedance of the
internal circuit is also relatively low, making pos
power windings of the motor have a high ratio of
inductive reactance to resistance, for example
sible a large current ?ow through the control
from 6 to 1 to 8 to 1, at the frequency of the al
winding.
ternating current supplied by the lines L’ and
The sections of the split transformer second
L", namely 60 cycles per second. This provides
ary winding I4I are so wound on the transformer
for maximum power during running with the
I38 that the anode 235 of the triode of the power
least amount of heating, and also provides a low
ampli?er I5 is driven positive during one half
impedance path in the control windings for 35 cycle of the alternating current supply voltage.
anti-hunting control purposes. By so designing
For convenience of explanation, this half cycle is
the motor, reduction in heating thereof during its
hereinafter referred to as the ?rst half cycle.
stalled condition is also obtained.
The anode 239 of the other triode is driven posi
Energizing current is supplied to the power
tive during the opposite or second half cycle and,
winding 33 of the motor through a circuit which 40 therefore, during the ?rst half cycle when the
may be traced from the alternating current sup
anode 235 is positive with respect to the center
ply line L’, through the power winding 33 and
tap on the split secondary winding I4I, the anode
a condenser 248 to the supply line L”. The con
239 is negative with respect to the potential of
denser 246 is so chosen with respect to the in
that center tap. During the second half cycle
ductance of the power winding 33 as to provide 45 the anode 239 becomes positive with respect to
a substantially series resonant circuit when the
the center tap of the secondary winding I4I
rotor 32 is rotating at approximately full speed.
while the anode 235 becomes negative with re
By virtue of this series resonant circuit the total
spect to the potential of the center tap. The volt
impedance of the power winding circuit is sub
age on the anode 235 accordingly increases and
stantially equal to the resistance of the power 50 decreases in phase with the supply line voltage
winding 33. Inasmuch as this resistance is rela
and the voltage on the anode 233 increases and
tively low, a large current flow through the power
decreases 180° out of phase with the supply line
winding is made possible resulting in the produc
voltage. This relation always remains substan
tion of maximum power and torque by the motor.
tially the same.
Due to the series resonant circuit also the current 55
The details of the motor drive system includ
?ow through the power winding 33 is substan
ing the ampli?er I 5 comprise no part of the pres
tially in phase with the supply line voltage. The
voltage across the power winding 33, however,
leads the current ?ow by substantially 90° be
cause of the inductance of the power winding.
ent invention, and therefore, further explanation
of the operation of the motor drive system is not
believed necessary herein, particularly since the
60 motor drive system is fully described in the co
When the rotor 32 is operating at substantially
pending application of Walter P. Wills, Serial
maximum speed, the apparent inductance of the
No. 421,173, ?led on December 1, 1941, and is also
power winding 33 is a maximum whereupon the
explehed in my copending application referred
series resonant circuit is resonant to the applied
to hereinbefore.
alternating current from the supply lines L’ and 65
When the rate of fluid flow through the con
L". As the speed of rotation of the rotor 32 de
duit I remains constant at the desired value, the
creases the apparent inductance of the power
frequency of oscillation of the high frequency
winding 33 decreases and therefore disturbs to
current output from the oscillator 4 is higher
some degree the resonant condition. This causes
than the frequency value to which the discrimi
a slight phase shift in the current through and 70 motor I0 is resonant by substantially the same
the voltage across the power winding, the voltage
amount that the frequency of oscillation of the
shifting somewhat more than the current and
high frequency current output of the oscillator
consequently reducing the power loss in the power
‘I is lower than the frequency value to which the
winding. In addition, the change from the reso
discriminator I2 is tuned. The undulating volt
nant condition causes a,‘ reduction in the cur- 75 age then impressed on the input circuit of the
23
2,404,344
triode section 223 of the mixing ampli?er M from
the discriminator I0 is of the same amplitude
but exactly 180° out of phase with the undulat
ing voltage impressed on the triode section 224
of the mixing ampli?er from the discriminator
l2. With such input voltages of the same ampli
tude impressed on the triode sections of the
mixing ampli?er M, the voltage drop produced
24
over, the speed of the motor IS in either direc
tion is directly dependent, within a predeter
mined range, upon the magnitude of the change in
the frequency of oscillation of the oscillator 4.
The rotation of the motor 16 operates through
a gear 36, the cable drum 39, cable 40 and cable
drum 44 to adjust the retuning condenser H
and also operates to adjust the position of the
across the common load resistance 233 in the
recording pen 53 and the indicating pointer, not
output circuit of the mixing ampli?er I4 is a 10 shown, relatively to the chart 54. In other words,
steady unidirectional voltage and does not in
the indicating pointer, not shown, operated by
clude any alternating components capable of
the shaft 31 from the gear 36 and pen arm 53
energizing the motor [6 to rotation, and as a
operated through the gear sector 51 by the gear
36 assume angular positions corresponding to the
consequence, the motor remains stationary.
Upon an increase in the rate of ?uid ?ow 15 angular adjustment of the detuning means 3, the
through the conduit l the manometer 2 operates
differential pressure in the manometer 2, and the
the detuning condenser 3 to give an adjustment
rate of ?ow through the conduit l for indicat
of the condenser plate 29 in the clockwise direc—
ing and recording the rate of flow through the
tion to decrease its capacity. This produces an
latter. The indicating scale cooperating with
increase in the frequency of oscillation of the 20 the indicating pointer, not shown, and the slowly
oscillator 4 which is operative to cause an in
rotating chart 54 cooperating with the pen arm
crease in the undulating voltage produced at the
53 may be suitably calibrated for indicating the
output terminals I69 and ill] of the discrimina
rate of flow through the conduit 1.
tor l0 whereupon the amplitude of the undulat
If the characteristics of the retuning condenser
ing voltage impressed on the input circuit of 25 ll correspond to the characteristics of the de
the triode section 223 of the mixing ampli?er
tuning condenser 3, the indicating scale and chart
I4 is increased with respect to the amplitude of
may be calibrated in accordance with those char
the undulating voltage impressed on the triode
section 224. A ?uctuating component of voltage
having the same frequency as that of the volt
age of the supply lines L’ and L" is then pro
acteristics or in accordance with the character
istics of the manometer 2. Uniform or even
30 graduations on the chart and indicating scale,
therefore, would indicate the differential pres
duced at the output terminals of the mixing am
sure existing within the manometer 2, and in
pli?er l4 and is impressed on the input circuit
order to indicate and record the rate of ?ow
of the power ampli?er l5 for selectively actuat
through the conduit l, the chart and scale must
ing the motor l6 for rotation in one direction.
have square root calibration. If it is desired to
The motor 16 then operates the retuning con
have a straight line calibration on the chart and
denser IT in the proper direction to effect a de
scale for indicating the rate of ?uid flow through
crease in the frequency of oscillation of the high
the conduit I, the retuning means I‘! may be so
frequency current output from the oscillator ‘l
designed as to eliminate the square root func
by an amount corresponding to the increase in 40 tion, as by suitable con?guration of the condenser
the frequency of oscillation of the high frequency
plates 48 and 49 with respect to each other.
currents applied to the discriminator 10 as re
Because the gear sector 5| operated by the
quired to equalize the amplitude of the undulat
gear 36 is positioned in accordance with the rate
ing voltage applied to the input circuit of the
of fluid ?ow through the conduit 1 or other~vari
triode section 224 of the mixing ampli?er I4, 45 able condition under measurement, the control
with the undulating voltage impressed on the
apparatus Him is operative to position the con
triode section 223.
trol valve [9 for maintaining the desired rate of
Upon a decrease in the rate of fluid flow
flow through the conduit I or for maintaining‘
through the conduit l, the manometer 2 oper
constant some other variable condition.
ates the detuning condenser 3 in the opposite 50
As those skilled in the art will understand, my
direction to give an adjustment to the condenser
present invention in its practical application is
plate 29 in the counter-clockwise direction to
not restricted to the use of a variable condenser
increase its capacity. This produces a decrease
3 for detuning the oscillator 4 in response to a
in the frequency of oscillation of the oscillator
change in the ?uid rate of flow through the con
4 and, therefore, a decrease in the amplitude of 55 duit I or in the particular variable condition un
the undulating voltage created at the output ter
der measurement, and also is not restricted to the
minals of the discriminator l0 and impressed on
use of a variable condenser I‘! for retuning the
the input circuit of the triode section 223 of
oscillator 1. For example, the detuning adjust
the mixing ampli?er M. The motor I6 is then
ments of the oscillator 4 may be effected solely
energized for rotation in the opposite direction 60 by means of variable inductive reactance ele
to effect an adjustment of the retuning con
ments, or by a combination of capacitive and in
denser l‘! in the reverse direction to cause the
ductive reactance elements. Similarly, the re
tuning adjustments of the oscillator ‘I may be
the discriminator l2 to decrease by an amount
effected solely by means of variable inductive re
corresponding to the decrease in the amplitude of 65 actance elements or by a combination of capaci
the undulation of the output voltage of the dis
tive and inductive reactance elements as disclosed
criminator [0. When such adjustment has been
in my aforementioned copending application.
given the condenser H, the motor 16 is not ener
When inductive reactance elements are employed
gized for rotation in either direction and re
for accomplishing the detuning and retuning ad
mains stationary. The motor I6, therefore, op 70 justments of the oscillators, it may be desirable
erates in one direction or the other accordingly
in some cases to provide inductive reactance ele
as the frequency of oscillation of the oscillator
ments of the type having high frequency coils in
4 increases or decreases from the value to which
order to produce a relatively large change in fre
the system is balanced with the particular ad
quency of oscillation for a small movement of the
amplitude of undulation of the output voltage of
justment of the retuning condenser II.
'
l
I
I
More
75 primary sensitive element.
vvulvll
28
2,404,344
25
In Fig. 6 I have illustrated more or less dia
grammatically a modi?cation of the receiver cir
cuit 6 which includes an alternative circuit ar
rangement which may be employed in lieu of the
oscillator 1, buffer II and discriminator l2 for
producing a 60 cycle per second undulating volt
age opposite in phase to that created at the out
put terminals of the frequency discriminator I0,
26
retuning means may comprise a variable differ
ential inductance or a variable differential re—
sistance as shown in Fig. '7.
In Fig. '7 a potentiometer resistance 260 pro—
vided with a contact 26! in slidable engagement
with the resistance 260 is connected across the
terminals of the tapped transformer secondary
Winding 254. When the contact 261 is in an in
and which may be utilized to control the triode
termediate position along the 1ength of resistance
section 224 of the mixing ampli?er M. The ar 10 260 no potential difference is developed across the
rangement of Fig. 6 is advantageous in that it
resistance 259, but upon movement of the contact
permits the oscillator 1, the buffer l I and the fre
26I in one direction away from that intermediate
quency discriminator l2 to be entirely dispensed
position an alternating voltage having a square
with and requires the use of only a comparatively
wave characteristic and of one phase relatively to
few components in place thereof.
15 the voltage of the supply lines L’ and L" is pro
As shown in Fig. 6 the undulating voltage for
duced across the resistance 259 while upon move
controlling the triode section 224 is created by a
ment of the contact 26l in the opposite direction,
signal generator indicated generally by reference
a square wave alternating voltage of opposite
character 248. Signal generator 248 operates to
phase is produced across the resistance 259. With
derive directly from the alternating voltage of 20 this modi?cation of my invention the indication
the supply lines L’ and L" a 60 cycle per second
signal voltage of variable magnitude and of re
versible phase. Since the output signal voltage
of the frequency discriminator It] comprises a
substantially symmetrical square wave of 60 cycles
per second, the signal generator 248 is also so
designed as to derive such a square wave voltage
signal from the supply lines L’ and L", which
supply lines ordinarily provide sinusoidal voltage.
produced by the pen 53 or the indicating pointer.
not shown, may be made to follow any desired
function of the variation of the detuning con
denser 3 by suitably shaping and designing the
resistance 268.
As those skilled in the art will understand, it
is not essential to the operation of the measuring
and controlling systems described in Figs. 1
through 7 that the frequency discriminator l0
To this end the signal generator 248 includes 30 and the discriminator 12, when employed, be of
two gaseous discharge tubes 249 and 258 which
the so-called balanced type. For example, the
are connected back-to-back across the primary
frequency discriminators l9 and I2 may be of
winding 25| of a transformer 252 and are also
the non-balanced type as disclosed in Fig. 8 and
connected in series with a protective resistance
indicated generally by the reference symbols I9’
253 across the supply lines L’ and L". The trans 35
and I2’. The use of such a discriminator is ad
former 252 also includes a center tapped sec
vantageous in that it makes possible an appre
ondary winding 254 across which a differential
ciable reduction in the amount of equipment in
volved. In each of the non-balanced frequency
denser 255 includes a pair of oppositely disposed 40 discriminators l0’ and I2’ shown in Fig. 8 only
one recti?er is employed. These recti?ers desig
and relatively stationary arcuate condenser plates
nated ‘by the reference numerals 262 and 263,
256 and 25'! and a movable arcuate condenser
each include an anode, a cathode and a heater
plate 258. The center tap of the transformer sec
?lament. The heater ?laments are connected
ondary winding 254 is connected to ground G and
the movable condenser plate or rotor 258 of the 45 to and receive energizing current from the trans
former secondary winding 91.
differential condenser 255 is grounded by means
The remainder of the frequency discriminator
of a resistance 259. Depending upon the position
I 0' comprises a transformer I49’ having a pri
of the movable condenser plate 258 with respect
mary winding 264 shunted by a condenser 265
to the relatively stationary plates 256 and 251,
a 60 cycle per second signal voltage of variable 50 and secondary winding 266 shunted by a con
denser 261, and also includes a resistance 26B
magnitude and reversible phase is produced across
shunted by a condenser 269. The recti?er 262
the resistance 259. This signal voltage produced
is connected in a series circuit with the trans~
across the resistance 259 is applied to the input
former secondary winding 266 and the parallel
circuit of the triode section 224 of the mixing
ampli?er l4 and the rotor or movable condenser 65 connected resistance 268 and condenser 269
plate 258 is mechanically coupled to the shaft of
through a circuit which may be traced from the
the motor l6 for rebalancing purposes, the differ
upper terminal of the secondary winding 266 to
ential condenser 255 in this modi?cation taking
the anode of the recti?er, to the cathode, the re
the place of the oscillator condenser IT in Fig. 2
sistance 268 and ground G to the lower terminal
as the retuning or follow-up condenser. The 60 of the secondary Winding 266. The condensers
condenser indicated generally by the reference
numeral 255 is connected. The differential con
manner in which the movable condenser plate
258 is mechanically coupled to the shaft of the
motor 16 may be the same as that in which the
265, 261 and 269 are so chosen as to tune the fre
quency discriminator I8’ to a desired frequency
near or in the region of the frequency of the high
retuning condenser I1 is mechanically coupled to
frequency currents generated by the oscillator 4.
the shaft of motor l6 in Figs. 1 and 2.
65 This frequency value to which the discriminator
It will be apparent that the detuning condenser
I0’ is tuned has been indicated in Fig. 9 by the
symbol in.
3 or the retuning differential condenser 255 may
be so designed and matched that the indication
The graph of Fig. 9 illustrates the resonance
produced by the pen 53 or the indicating pointer,
curve of the discriminator ID’. This resonance
not shown, may be made to follow any desired 70 curve is representative of the manner in which
function of the variation of the detuning con
the amplitude of the undulating potential drop
denser 3. It Will be understood also that the
produced across the resistance 268 and the par
retuning means for the modi?cation illustrated
allel connected condenser 269 varies as the fre
in Fig. 6 need not necessarily comprise a differ
quency of the modulated high frequency oscilla
‘tial condenser as shown at 255, but if desired, said 75 tiOns applied to the discriminator l0’ deviates
'
I
2,404,344
27
28
from the value to which the discriminator is
tuned. It is contemplated that the apparatus
mixing ampli?er M. The contact 283 is ar
ranged to be adjusted along the length of the
slidewire resistance 282 by the reversible motor
may be so arranged that the amplitude of the un
dulating potential drop produced across the re
sistance 268 may vary between the points a and
I) along the curve of Fig. 9 as the detuning con
denser 3 is adjusted through its entire range of
movement. It will be understood that, if desired,
the apparatus may be so arranged that the points
a and b may fall on the portion of the curve of
Fig. 9 to the left of the center frequency f0 in
stead of the right of that frequency, as shown.
The remainder of the frequency discriminator
[2' comprises a transformer 210 having a primary
winding 21! shunted by a condenser 212 and a
secondary Winding 213 shunted by a condenser
214, and also includes a resistance 215 shunted
by a condenser 216. The recti?er 263 is con
nected in a series circuit including the trans
former secondary winding 213 and the parallel
connected resistance 215 and condenser 216. The
construction and operation of the frequency dis~
criminator I2’ is substantially identical to that
l6, and to this end, the manner of mechanical
coupling of the shaft of the motor Hi to the
resistance 282 and contact 283 may be the same
as that in which the retuning condenser I1 is
mechanically coupled to the shaft of motor l6
in Figs. 1 and 2. The operation of the tube 218
is such that a square wave alternating voltage
of the same frequency as that of the line wires
L’ and L" is produced across the resistance 282.
That square wave alternating voltage is variable
in magnitude depending upon the position of the
contact 283 along the length of the resistance 282.
Consequently, upon change in amplitude of the
square wave alternating voltage produced across
the parallel connected resistance 268 and con
denser 269 of Fig. 8, the motor 16 is energized
for operation in the proper direction to effect a
corresponding change in the square wave alter
nating voltage tapped off the resistance 282 by
the contact 283 to thereby restore a steady volt
age drop across the load resistance 233' in the
of discriminator l0’ and creates an undulating
voltage of the same frequency as that of the volt 26 output circuit of the mixing ampli?er l4, and
age of the ‘supply lines L’ and L" as the fre
hence, to rebalance the system.
While in accordance with the provisions of the
quency of the modulated high frequency oscilla
tions applied to the frequency discriminator l2’
statutes, I have illustrated and described the best
form of this invention now known to me, it will
deviates from the frequency value to which the
discriminator I2’ is tuned.
30 be apparent to those skilled in the art that
changes may be made in the form of the appa
The undulating output voltage of the discrimi
ratus disclosed without departing from the spirit
nator I0’ is applied to the input circuit of the
of my invention as set forth in the appended
triode section 223 of the mixing ampli?er l4 while
the undulating output voltage of the discrimi
claims, and that in some cases certain features of
nator i2’ is applied to the input circuit of the 35 my invention may sometimes be used to advan
tage without a corresponding use of other fea
triode section 224, the connection-5 being such
that the undulating voltage upon the control grid
tures.
226 is 180° out of phase with that on the control
Having now described my invention, what I
grid 238. When the amplitudes of the two un
claim as new and desire to secure by Letters
dulating voltages are the same, a substantially 40 Patent, is:
steady current flows through the common load
1. In combination, means to generate an oscil
resistance 233 producing a substantially steady
potential drop thereacross, while an undulating
lation of relatively high frequency, frequency dis
criminating means responsive to said high fre
voltage of one phase or of opposite phase rela~
quency oscillation to produce a voltage of am
tively to the voltage of the supply lines L’ and
L” is produced across resistance 233 when the
amplitude of one undulating voltage is greater
plitude varying in accordance with the frequency
of said oscillation, means to modify the amplitude
of said oscillation during predetermined time
intervals of a second oscillation of relatively
or less than that of the other.
In Fig. 10 I have illustrated, more or less dia
low frequency to produce a resulting voltage of
grammatically, a modi?cation of the receiver 50 amplitude variable in accordance with the fre
circuit of Fig. 8 which includes an alternative
quency of said oscillation and undulating at said
circuit arrangement which may be employed in
low frequency, means to produce a second voltage
of variable amplitude and undulating at said
lieu of the oscillator 1. buffer II, and the non
balanced discriminator 12' for producing a 60
low frequency, and means to compare the am
cycle per second undulating voltage opposite in 55 plitudes of said undulating voltages.
phase to that created at the output terminals
2. In combination, means to generate an oscil
of the frequency discriminator l0’ and which
lation of relatively high frequency, frequency dis
may be utilized to control the triode section 224
criminating means responsive to said high fre
of the mixing ampli?er l4. With the arrange
quency oscillation to produce a voltage of am
ment in Fig. 10 the undulating voltage for con 60 plitude varying in accordance with the frequency
trolling the triode section 224 is created by a
of said oscillation, means to modify the amplitude
signal generator indicated by the reference sym
of said oscillation during predetermined time
bol 211 and which is operative to derive directly
intervals of a second oscillation of relatively low
from the alternating voltage supply lines L’ and
frequency to produce a resulting voltage of am
L" a square wave 60 cycle per second signal volt 65 plitude variable in accordance with the frequency
age of variable magnitude but of constant phase.
of said oscillation and undulating at said low
The elements of the tube 218 are connected be
frequency, means to produce a second voltage of
tween the supply lines L’ and L" through block
variable amplitude and undulating at said low
ing condensers 219 and 288 and a protective re
frequency, means to produce a ?uctuating Volt
sistance 28!, as shown. A potentiometer resist
0 age of said low frequency and of one phase or
ance 282 has its terminals connected to the ter
of opposite phase accordingly as the amplitude
of said resulting voltage is greater or less than
minals of the tube 218 and has one terminal con
nected to ground G. A contact 283 in slidable
the amplitude of said second voltage, and phase
engagement with the resistance 282 is connected
responsive means controlled by said ?uctuating
to the control grid of the triode section 224 of the 1‘ voltage to vary the amplitude of said second volt
v
s
a
28
2,404,344
29
30
age to substantially equalize the amplitudes of
said resulting and second voltages.
by to cause said output voltage to undulate at
3. In combination, means to generate an oscil
voltage of variable amplitude and undulating at
lation of relatively high frequency, frequency dis
said low frequency, and means to compare the
criminating means responsive to said high fre
quency oscillation to produce a voltage of ampli
tude varying in accordance with the frequency of
said oscillation, means to modify the amplitude
of said oscillation during predetermined time in
amplitudes of said undulating voltages.
said low frequency, means to produce a second
'7. In combination, means responsive to oscil
lations applied thereto of relatively high fre
quency characterized by their frequency and am
plitude, said means being adapted to produce in
tervals of a second oscillation of relatively low 10 response to said oscillations a unidirectional out
frequency to produce a resulting Voltage of am
put voltage characterized by its amplitude and
plitude variable in accordance with the frequency
polarity, means to modify at least one of the char
of said oscillation and undulating at said low
frequency, means to produce a second voltage of
variable amplitude and undulating at said low
frequency, means to produce a ?uctuating volt
age of said low frequency and of one phase or of
acteristics of said oscillations during predeter
mined time intervals of an oscillation of rela
tively low frequency thereby to modify at least
one of the characteristics of said output voltage
in order to produce a variable amplitude output
voltage undulating at said low frequency and of
one phase or of opposite phase depending upon
opposite phase accordingly as the amplitude of
said resulting voltage is greater or less than the
amplitude of said second voltage, and reversible 20 the sense in which said one of said high frequency
motor means selectively controlled for rotation
oscillation characteristics is modi?ed, means to
produce a second voltage of variable amplitude
in one direction or the other by said ?uctuating
voltage according to its phase to vary the ampli
and phase and undulating at said low frequency,
tude of said second voltage to substantially
and means to compare the amplitude and phase
of said undulating voltages.
equalize the amplitudes of said resulting and sec
ond voltages,
8. In combination, means responsive to oscil
lations applied thereto of relatively high fre
4. In combination, first and second oscillators
quency characterized by their frequency and am
to generate an oscillation of relatively high fre
plitude, said means being adapted to produce in
quency, ?rst and second frequency discriminators
each responsive to an individual one of said high
response to said oscillations a unidirectional out
put voltage characterized by its amplitude, means
frequency oscillations and each operative to pro
duce an output voltage of amplitude varying in
to modify at least one of the characteristics of
said oscillations during predetermined time in
accordance with the frequency of the associated
tervals of an oscillation of relatively low fre
oscillation, means to modify the amplitude of
quency thereby to produce an output voltage un
each of said oscillations during predetermined
dulating at said low frequency and of amplitude
time intervals of a second oscillation of relatively
low frequency to produce a resulting output volt
variable in accordance with the frequency of said
age from each of said discriminators oi ampli
high frequency oscillation, means to produce a
second voltage of variable amplitude and undu
tude variable in accordance with the frequency
of the associated oscillation and undulating at 40 lating at said low frequency, means responsive to
differences in the amplitudes of said undulating
said low frequency, and means to compare the
amplitudes of said undulating voltages.
voltages, and means controlled by said last men
tioned means to vary the amplitude of one of said
5. In combination, ?rst and second oscillators
to generate an oscillation of relatively high fre
undulating voltages to maintain equality of said
amplitudes.
quency, ?rst and second frequency discriminators
each responsive to an individual one of said high
9. In combination, means responsive to oscil
frequency oscillations and each operative to pro
lations applied thereto of relatively high fre~
duce an output voltage of amplitude varying in
quency characterized by their frequency and am
plitude, said means being adapted to produce in
accordance with the frequency of the associated
response to said oscillations a unidirectional out
oscillation, means to modify the amplitude of
each of said oscillations during predetermined
put voltage characterized by its amplitude, means
time intervals of a second oscillation of relatively
low frequency to produce a resulting output volt
to modify at least one of the characteristics of
said oscillations during predetermined time inter
vals of an oscillation of relatively low frequency
age from each of said discriminators of ampli
tude variable in accordance with the frequency 55 thereby to produce an output voltage undulating
at said low frequency and of amplitude variable
of the associated oscillation and undulating at
in accordance with the frequency of said high fre
said low frequency, means to produce a ?uctuat
ing voltage of said low frequency and of one phase
quency oscillation, means to produce a second
voltage of variable amplitude and undulating at
or of opposite phase accordingly as the amplitude
of one of said resulting output voltages is greater 60 said low frequency, and means responsive to dif
ferences in the amplitudes of said undulating
or less than the amplitude of the other of said
voltages to vary one of said undulating voltages
resulting output voltages, and phase responsive
as required to reduce said differences.
means controlled by said fluctuating Voltage to
10. In combination, means responsive to os
adjust the frequency of oscillation of one of said
oscillators to maintain the amplitudes of said re
cillations applied thereto of relatively high fre
sulting voltages substantially identical.
quency characterized by their frequency and am
6. In combination, means responsive to oscilla
tions applied thereto of relatively high frequency
characterized by their frequency and amplitude,
said means being adapted to produce in response
to said oscillations a unidirectional output; volt
age characterized by its amplitude, means to
modify at least one of the characteristics of said
plitude, said means being adapted to produce in
response to said oscillations a unidirectional out
put voltage characterized by its amplitude, means
to modify at least one of the characteristics of
said oscillations during predetermined time inter
vals of an oscillation of relatively low frequency
thereby to produce an output voltage undulating
oscillations during predetermined time intervals
at said low frequency and of amplitude variable
of an oscillation of relatively low frequency there 75 in accordance with the frequency of said high
a
>
a
2,404,344
31
frequency oscillating, means to produce a second
voltage of variable amplitude but of opposite
phase and undulating at said low frequency, a
mixing ampli?er having a first input circuit upon
which said ?rst mentioned undulating voltage is
impressed and a second input circuit upon which
said second mentioned undulating voltage is im
pressed and having a unidirectional voltage ener
gized output circuit common to each of said input
circuits, and means connected to the output cir
cuits of said mixing ampli?er to vary one of said
undulating voltages as required to maintain a
age of variable phase and amplitude and undu
lating at said low frequency, and means to com
pare the phase and amplitude of said undulating
voltages.
14. In combination, a balanced frequency dis
criminator responsive to oscillations applied
thereto of relatively high frequency characterized
by their frequency and amplitude, said discrimin
ator being adapted to produce in response to
change in the frequency of oscillation of said os
cillations from a predetermined value a unidirec
tional output voltage characterized by its ampli
substantially steady current flow in said output
tude and polarity, means to modify at least one
of the characteristics of said oscillations during
11. In combination, ?rst and second balanced 15 predetermined time intervals of an oscillation of
frequency discriminators each responsive to os
relatively low frequency thereby to modify at
cillations applied thereto of relatively high fre
least one of the characteristics of said output
quency characterized by their frequency and am
voltage in order to produce a discriminator out
plitude, each of said discriminators being adapted
put voltage undulating at said low frequency and
to produce in response to said oscillations a uni 20 of phase and amplitude in accordance with the
directional output voltage characterized by its
direction and extent of change of the frequency
amplitude and polarity, means to modify at least
of oscillation of said oscillations from said pre
one of the characteristics of each of said oscilla
determined value, a network including a differ
tions during predetermined time intervals of an
ential condenser adjustable to derive from an un
oscillation of relatively low frequency thereby to 25 dulating voltage of said low frequency and of
modify at least one of the characteristics of each
?xed phase and amplitude applied to said net
of said output voltages in order to produce dis
work a second voltage of variable phase and am
circuit.
criminator output voltages undulating at said
plitude and undulating at said low frequency,
low frequency and of amplitude variable in ac
cordance with the frequency of the associated
high frequency oscillations, and means to com
pare the amplitudes of said undulating voltages.
12. In combination, ?rst and second balanced
frequency discriminators each responsive to os
and means to compare the phase and amplitude
of said variable undulating voltages.
15. In combination, a non-balanced frequency
discriminator responsive to oscillations applied
thereto of relatively high frequency character
ized by their frequency and amplitude, said dis
cillations applied thereto of relatively high fre 35 criminator being adapted to produce in response
quency characterized by their frequency and am
to said oscillations a unidirectional output volt
plitude, each of said discriminators being adapted
age characterized by its amplitude, means to
to produce in response to said oscillations a uni
modify at least one of the characteristics of said
directional output voltage characterized by its
oscillations during predetermined time intervals
amplitude and polarity, means to modify at least 40 of an oscillation of relatively low frequency there
one of the characteristics of each of said oscilla~
by to modify the amplitude of said output voltage
in order to produce a discriminator output voltage
undulating at said low frequency and of ampli
tude varying in accordance with the frequency
modify at least one of the characteristics of each
of said output voltages in order to produce dis 45 of the associated high frequency oscillations,
means to produce a second undulating voltage of
criminator output voltages undulating at said
variable amplitude and undulating at said low
low frequency and of amplitude variable in ac
tions during predetermined time intervals of an
oscillation of relatively low frequency thereby to
cordance with the frequency of the associated
high frequency oscillations, means to compare the
amplitudes of said undulating voltages, and
means responsive to differences in the amplitudes
of said undulating voltages to adjust the fre
quency of oscillation of one of said high frequency
oscillations as required to reduce such differ
55
ences.
frequency, and means to compare the amplitudes
of said undulating voltages.
16. In combination, a frequency discriminator
responsive to oscillations applied thereto of rel
atively high frequency characterized by their fre
quency and amplitude, said discriminator being
adapted to produce in response to said oscilla
tions a unidirectional output voltage character
ized by its amplitude, means to modify at least
13. In combination, a balanced frequency dis
one of the chracteristics of said oscillations dur
criminator responsive to oscillations applied
ing predetermined time intervals of an oscillation
thereto of relatively high frequency characterized
of relatively low frequency thereby to modify the
by their frequency and amplitude, said discrim 60 amplitude of said output voltage in order to pro
inator being adapted to produce in response to
duce a discriminator output Voltage undulating
change in the frequency of oscillation of said
at said low frequency and of amplitude varying
oscillations from a predetermined value a, uni
in accordance with the frequency of the associ
directional output voltage characterized by its
ated high frequency oscillations, a network in
amplitude and polarity, means to modify at least 65 cluding an adjustable potentiometer resistance
one of the characteristics of said oscillations dur
to derive from an undulating voltage of said low
ing predetermined time intervals of an oscilla
frequency applied to said network a second un
tion of relatively low frequency thereby to modify
dulating voltage of variable amplitude, and means
at least one of the characteristics of said output
to compare the amplitudes of said variable undu
voltage in order to produce a discriminator output 70 lating voltages.
voltage undulating at said low frequency and of
17. In combination, ?rst and second non-bal
phase and amplitude in accordance with the di
anced frequency discriminators each responsive
rection and extent of change of the frequency of
to oscillations applied thereto of relatively high
oscillation of said oscillations from said prede
frequency characterized by their frequency and
termined value, means to produce a second volt 76 amplitude, each of said discriminators being
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