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Патент USA US2411605

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Nov. 26, 1946.
R„ Q_ WEBB
ELECTRICAL CIRCUITS
Filed Feb. 25, 1945
2,411,605
2,411,605
3
4
nator tubes 25 should preferably be provided with
two control grids which are nearly equally eñ’ec
tive in controlling the plate current flowing
through the tubes. For this purpose, tubes of the
electrode 31 may now be represented by the vec
tor 0_30, and the voltage applied to the control
electrode 39 may be represented by the vector
0_3?. As was the case in connection with the
vector series of curves of portion (a) of the iig
general character such as pentagrid converters
may be used.
The secondary Winding 29 of the transformer
ure, the plate currents flowing through the tubes
25-and 21 naturally are still proportional to the
2| is suitably tuned by means of the tuning ca
pacitor 3|, and output energy from this resonant
vector sums of the two grid voltages which are rep
resented by the vectors 0_39 and O-24, on the
one hand, and O--32 and 0_24 on the other
hand, so that now it will be seen that the result
'ant vectors are indicated by the vectorO--SS as
secondary circuit consisting of the inductance
of the secondary winding 29 of the interstage
transformer 2| and the tuning capacitor 3| is
fed by way of the conductors 33 and 35, respec
representing the output from the tube 25, and
tively, to the #l control grids 31 and 39 of the
the Vector 0_38 as representing the output from
discriminator tubes 25 and 21, respectively.
15 the tube 21.
The second control grid 4| and 43 of the tubes
It thus can be seen that for a condition where
25 and 21, respectively, are tied together, pref
erably by the conductor 45, and -excited directly
Ythe frequency is increased, unequal plate cur
blocking condenser and functioning in substan
tially known manner. The resistor element 5|
serves to connect the biasing source, convention
ally represented by the battery 53, to bias the
the tube 21, whereas for a decrease in the input
grids 4| and 43 to a suitable place as an operat
ing point -within the region of plate current cur
driven positive with respect to the cathodes by
reason of the bias obtained thereon through the
rents result, and the flow of these currents
from the plate or anode |1 of the driver tube I5
through the load resistors 55 and 61 produces
by way of the coupling condenser 41 and conduc 20 useful output variations. In the case where the
tor 49, with the condenser 41 constituting a
frequency is increased, it can be seen that the
output from the tube 25Vbecomes greater than for
frequency, the opposite'condition will take place.
Since the grids of the tubes 25 and 21 are never
vature. The plate or anode battery 55 supplies
biasing source 53, it can be seen that these tubes
not only the operating voltage for the plates 51
represent a load of substantially infinite imped
and 59 of the tubes 25 and 21, respectively, but 30 ance on the resonant circuit and the result is that
also supplies the operating voltages for the
the output characteristic approaches more close
screen electrodes 6| and E3 of these same tubes.
ly the phase shift curve of the resonant circuit
Variations in resultant output energies iiowing
alone.
_
through the tubes 25 and 21 are derived as use
In the modified arrangement of Fig. 3, provi
ful plate .current variations in accordance with
sion has been made for a discriminator circuit
the voltage drops produced through the resistors
which is particularly adapted for operation with
65 and 61, which voltages are made available at
in the audio frequency range. To this end, in
put signals are applied at the input terminals 13,
15 and then serve to energize the primary wind
the terminal points 69 and 1|, respectively.
Considering the operation of the circuit here
inabove explained, reference may be had to Fig. 40 ing I9' of the interstage transformer 2|', which
2, wherein the curve (a) represents a condition
when the circuit arrangement of Fig. l is in bal
is n_ow shown particularly as an audio frequency
transformer, in order to energize the secondary
ance, so that the vectors O-Zß and O-22 rep
winding indicated as 29’. The general arrange
resent the voltages applied to the control elec
_ment of the tubes 25 and‘21 is somewhat similar
trodes 31 and 39, respectively. It is, of course, 45 vto that shown by Fig. l with the control elec
apparent that each of these voltages is 90° out
trodes or grids 31 and 39 being energized by con
of phase with respect to the voltage represented
nection to the outer terminalsrof the transform
by the vector O-24 which represents that volt
er secondary 29', and the grids 4| and 43 being
age which is applied to the parallelly connected
parallelly connected and thus energized co-phas
grids 4| and 43, which shift in voltage is due to
ally, as well indicated with reference to the ar
the resonant transformer action of the interstage
rangement of Fig. 1.
transformer 2|, and naturally the currents
In connection with the arrangement of Fig. 3,
however, it will be noted that the grids 4| and
43, while connected together, now connect by
drawn by the plates or anodes 51 and 59 vof the
tubes 25 and 21 willV then be represented as being
proportional to the vector sums of the grid volt
ages O~-20 and O--24, on the one hand, and
0_22 and 0_24 on the other hand, so that
these may ¿be represented now by the vectors
0_25 and 0_28, respectively.
way of a conductor 11 to an intermediate point
19 representing the junction of the serially con
nected capacitor 8| and‘resistor 83, which to
gether are connected in parallel with the trans
Thus, the out
puts `'from tubes 25 and 21 are equal for this con
dition, and a balanced condition is obtained with
no useful output at terminals 59 and 1|.
Referring now more particularly to curve (b)
of .Fig..2, it will be seen that a condition has
been represented when the applied frequency has
been raised in value, for instance, so that now
the Vvoltages appearing at the control electrodes
31 and 39 will no longer be represented by vec
l
former secondary 29’. Y
60
In connection with the operation of the c_ir
cuit shown by Fig. 3, reference will now be made
to the vector analysis represented by the vectors
of Fig. 4. Referring to Fig. 4, and ñrst topor
tion (a) thereof, it will be seen that the vector
O-44 represents the voltage applied to the grid
electrodes 4| ~and 43 which are parallelly con
nected and that -such voltage will be 90° out 'of
phase with the voltages represented by the vec
tors which are 90° out of phase with respect to
tors O-40 and O--42, respectively, whenY the ap
the voltage represented by the vector O--24 as 70 plied frequency is such that the capacitive re
applied to the control electrodes or grids 4| and
actance of the condenser 8| is equal to the resist
43, but, due to the characteristics of the resonant
circuit consisting of the transformer secondary
29and» the capacitor 3|, a phase shift has oc
curred so that the voltage applied to the QOntrol
ance of the resistor 83.
f
I
As `was above explained, the plate currents now
ing from the tubes 25 and 21 are proportional to
the vector sums of the grid voltages, that is,
2,411,605
_ for instance, thev grid voltageïOä-Mappearing on
the grid 4| and the grid voltage 0*-40 appear
two signal actuated-- controlîelectrodes, A»meansQfor
» supplying vfrequency‘modulated signal energy in
180° -out-of-phase relationship to one control
electrode element of each tube, means for sup
ing on the grid- 31 of the tube 25 willf produce a
plate current which is» proportional tothe vsui-ns
of these voltages which can be represented by the .
vector O-Mì, or likewise, the platecurrent flow
ing through-the tube 21 on vconditions wher-ey the
plying ’thev frequency modulated» signal energy
cophasally upon a second control electrode ele
` ment of each tube with thesuppiied signal energy
normally shifted 90° in phase relativeto the signal
voltages on the grids 39 and 43 are 90° out of
phase may be representedby the vector O--48.
In this formand under these condi-tions, a 'bal'
anced condition is obtained, Vas explained by ref-‘
erence to Fig. 2(a) .
A
,
However, let it be supposed that- the applied
energy supplied to the' first control` electrode ele
iov
ment of each tube, ' and' phase shifting means
. comprising a serially connected capacity and re
sistance element operative upon a shift inY the
frequency of the suppliedv signal energy for al'
tering the relativ-e vphase differences of the sig
frequency is increased.` Then it can’be seen that
the> voltage representedv by the vector O-M that l5 nal energy applied to the first and second con
trol electrode elements of each tube to produce
is applied toA the grids 4'! and 43 begins> to llag
thereby output energy of varying magnitudes
and occupies now a portion represented as Of---54
from each tube.
_
as in vectorY series (li), but the voltageshereto
2. A detector circuit comprising a pair of mul
fore represented as OL-ílil andI O=-`42 by the vec*
tor series (a) occupy the vsame relative position ‘ tielectrode thermionic devices each havingV a plu
rality of input and control circuits and a single
and are now represented >by vector series (b) as
0_50 and O-52, respectively. Under such cir
cumstances, it is apparent that the plate cur
rents flowing from the tubes 25 and 21 are now
no longer equal, but to the contrary, are unequal
and are proportional now tothe vectors O>--56
and O»--58, with that represented by the vector
Ote-58 being larger than O---56. for the degree of
phase shift introduced by reason of thevolt
ages applied to the grids `¿H and' d'3.'
It therefore becomes apparent that when the
audio frequency is either raised or lowered,`the
plate currents from the tubes 25 and 21 become
unequal, and that one plate current is increas
ing while the other is decreasing. The result is
that voltage drops are produced across the resis
tors 65 and 61 which now become useful in pro
output circuit, .means to supply frequency modu
lated signalling voltages to one like input circuit
of each of said devices with a phase variancev of
180° in the energy supplied to each ofV the said
input circuits of the tubes, means to supply the
frequency modulated signalling voltages to the
second input circuits of the said tubes cophasally,
means including a serially connected capacity
and resistance element for supplying voltage to
the last named input circuitsl of the tubesl with
a 90° phase shiftA relative to the voltage sup
plied to the first named input circuits for condi
tions of equilibrium, means t0 produce phase var
iances from the normal 90° phase 'difference be-
tween the voltages applied to the said two input
circuits of each of the tubes upon frequency
changes in the supplied signalling voltages, and
viding output variations. It, of course, might be
an output circuit responsive to the said 90° phase
apparent that the general arrangement of the
shift variances in the voltages supplied to the
iiff)
condenser and resistor serially connected could
said input circuits.
be replaced by other reactive combinations in
3. A detector circuit comprising an energy
order to provide the desired effects, and then
transfer means having outer terminals whereat,
suitable tuningsuch as shown, for instance, by
upon excitation, Voltages are developed which
Fig. 1 might be applied across the transformer . are out-of-phase with respect to each other, a
secondary 29’ as there indicated also.
center tap connection to the said energy trans
While the invention has been described in such
fer means, a series circuit connected in shunt
a manner that one signal is placed upon one con
with the said energy transfer means and between
trol electrode and the other signal is placed upon
the outer terminals thereof, said series circuit
the other control electrode of each tube, it, of
comprising a resistance and a capacity element
50
course, will be apparent that the input signals in
of which the capacitive reactance of the condenser
the normal 90° phase relationship may be ap
is equal to the resistance of the resistor at a pre~
plied to either of the control electrodes where
determined output frequency of the said energy
the parameters or geometry of the tubes 25 and
transfer means, an voutput connection at the
21, for instance, are such that either of the con
junction point ofthe said resistance and con
55
trol grids 31 or lêl, on the one'hand, and 39 and
denser elements whereby, for predetermined im
43 on the other hand are equally effective in con
pressed frequency values on the said energy trans
trolling the electron flow between the cathode '
fer means, a voltage is developed between the said
and anode elements of thetube. Under such
center tap connection and the output connection
circumstances it is apparent Vthat one signal
to the junction of the condenser and resistor
60
might be applied to one control electrode and
which is 90° out-of-phase relative to each of the
the other signal applied to the other control
voltages developed between the said center tap
electrode interchangeably, and consequently the
connection and the outer terminals of said energy
connections to each of the tubes might be dif
transfer means and at other frequencies the said
ferent but only so long as each control electrode
65 voltage developed between the said center tap
is equally effective in its operation.
Y
connection and the junction of the said resistance
Other modifications naturally will become ap
Vand condenser shifts closer or farther away from
parent and suggest themselves at once to those
the said normally out-of-phase voltages at the
skilled in the art in the light of the invention set
outer terminal of the said energy transfer means.
forth by the following claims.
Y 4. A 'detector circuit including a pair of therm
Having described the invention, what is claimed 70 ionic tubes each having an output electrode and
1s:
at least two signal actuated control electrodes,
1. A circuit for detecting frequency modulated
means for applying frequency modulated signal
signal energy comprising a pair of thermionic
ling voltage in 180° out-of-phase relationship to
tubes each having an output electrode element
like
signal actuated control electrode elements of
75
connected to a common load circuit and at least
I2,411,605
7
8
each of the said tubes, an electrical network com
prising a series combination of a resistance ele
-ment and a capacity element connected between
said last named electrodes, said capacity and re
sistance elements being of such size that at a pre
determined frequency the capacitive reactance of
the capacity element is equal to the resistance of
the' resistance element, a connection to second
like signal actuated control electrode elements of
said tubes from the junction point of said capacity
predetermined ~impressed frequency the signal
voltages applied to the two said input circuits of
and resistance elements whereby, at a normally
predetermined impressed frequency, the signal
voltages applied to the two said control electrodes
of the said tubes are 90° out-of-phase relative to
each-other, and at other frequencies the phase
angle between the two said applied voltages in
creases and decreases in proportion to changes
in frequency.
5. A detector circuit including a pair of therm
ionic tubes each having an output circuit and at
least two signal actuated input circuits, means for
applying frequency modulated signalling voltage
in 180° out-of-phase relationship to like input
circuits of each of the said tubes, an electrical net
WOI‘k Comprising a series combination of a re
the said tubes are 90° out-of-phase relative to
each other, and at other frequencies the phase
angle between the two said applied voltages in~
creases and decreases in proportion to changes in
frequency and output voltages proportional to
frequency changes are developed in the said out
put circuits.
'
6. A detector circuit including a pair of therm
ionic tubes each having an output electrode ele
ment and at least two signal actuated control
electrodes, input connections to apply normally
180° out-of-phase voltages to a first like control
electrode element of each tube, a phase shifting
network comprising a serially connected capacity
element and a resistance element connected loe
tween said first named like control electrode ele
ments, a connection from each of the second like
control electrode elements of each tube to the
junction point of'said serially connected1 capac
ity and resistance elements whereby, for condi
tions When the resistance of the said resistance
element is equal to the capacitive reactance of the
capacity element, a voltage is applied to the second
like control electrode elements which is 90° out-of
phase relative to the first supply voltage and for
other frequency values of impressed energy the
relative phase difference varies substantially pro
sistance element and a capacity element connected
.in shunt with sai-d last named input circuit, said
capacity and resistance elements being of such
size that, at a, predetermined frequency, the ca
pacitive reactance of the capacity element is equal 30 portionally, thereby to produce output energy
to the resistance of the resistance element, a con
from the two said output electrode elements which
nection between the second like input circuit of
is proportional to the change in frequency applied.
said tubes and the junction point of said capacity
and resistance elements, whereby at a, normally
RICHARD C. WEBB.
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