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Sept. 10,1946;
Filed April 4; 1942
2 Sheets-Sheet 1
mung, QNRSBQ
‘ Philip C.Mich_e\,
is Attor‘ney.
Sept. 10, 1946.
P. c. mam-:1.
2,407,505 ' I
Fileql April 4, 1942
L< I
L——\//.¢. -
' 2 Sheets-Sheet 2
pJ4 17
Philip C.Michel,
y His’ Attorney.
Patented Sept. 10,’ 1946
Philip 0. Michel, Schenectady; N. Y., assign‘or: to
General’ Electric Company, a corporation of
New York
Application April 4, 1942, Serial No. 437,627
9 Claims.
(Cl. 250-27)
Thefpresent‘ application is‘ a continuation-in‘
instantithat control voltage-?uctuation impulses
part of my copending' application, Serial No. 419,
035,v ?led November'13, 1941, Patent No. 2,324,
314', datedJuly 13; 1943, and assigned. to the
pass through zero'value or “cross? the zero line.”
It is also desirable to‘ prevent the'switching unit
from being actuated in response to spurious ?uc
same assignee as the’ present application;
My' present invention relates to‘ circuits em
ploying electric discharge devices or’ electric
valves and‘ concerns particularly arrangements
for: use in impulse‘ c'ounting'and interval timing;
It is an object of my'invention to provide im 10
tuations which maybe produced by stray induc
tive'effectsv in conductors. carrying the genuine
control'impulses. Such. spurious voltage ?uctua
proved: arrangements" for' transmitting impulse
signals to impulse‘ responsive devices within
creased precision withregard to'the instant of
actuation of the‘ impulse‘ responsive‘ device. and
with high accuracy and'rrelia'bility- with regard
to the rejection of ‘spurious ‘signals:
Another object‘ of my inventionvv islto' provide
impulse transmitting‘ arrangements which may
readily‘be adjusted for various degrees of spu
rious signal rejection, and which are provided
with arrangements for testing the impulse trans
mitting circuits together with’ the impulse re
tions- are frequently referred to as noise.
In carrying‘out my invention in its preferred
form I provide a pair of input terminals to which‘
a pair of insulated. conductors may be connected
or coupled. ' These: conductors. carry the control
impulses from‘ the source‘ at which they are
generated. Since it‘may" be necessary that these
conductors be of‘ appreciable length; they have
a tendency to‘ pick up voltage. with‘ respect to
ground. For eliminating such line to' ground
voltages or noises,‘ I interposei a signal ampli?er
and. line‘ to‘ ground attenuator between ‘the input
terminals and a second pair of terminals referred
to as intermediate't'erminals. Between'these in
termediate terminals and the‘?nal outputv termi
sponsive'devices, counterszoninterval- timers as
nals two different circuits are‘ provided, one‘ in
sociated" therewith.
cluding a voltage diiferentiator and the‘other in
Other and further’objects and. advantages. will 25 cluding a voltage‘ integrator; The ?nal output
become apparent as. the following description
terminals here referredfto are connected. to the
control‘ terminals of the‘ switching unit. These
The apparatus; to which the‘ present applica
two‘ circuits actually terminate in the control
tion relates may be used‘, and is‘ particularly‘use
electrodes‘ of ‘ a‘ current-controlling‘ device having
ful, in conjunction with “on” and “oif’.” control
two' different control electrodes each of which
impulse-producing. devices-employed to‘ measure
must be maintained at’ a potential. exceeding a
time intervals. Relatively: short time ‘ intervals
predetermined value‘ in order'for the current
may be measured accuratelyby' counting‘ the
controll'ing device‘to pass current. The“ current
number of cycles of a. source’ of‘ highconstant
controlling- device‘ is'operatively interposed in
frequency impulses which are produced during .
the circuit to the .output'terminals.
the time interval betweentwo control impulses.
A switching unit is.~ interposed between the high
frequency cyclegenerator and‘ a" cycle counter
and‘ the switching unit is designed: to turn “on”
The ?rst circuit between the said intermediate
terminals and the current-controlling device also
includes a clipper for‘ converting the‘ single-cycle
input impulses into a square topped wave in ad
and “off” in response to the twoxsucoessivezcon 40 dition to the’ di?erentiator which'is for convert
trolimpulses. The apparatus t'o'which the pres‘
ing the square topped wave into a single sharp
ent’application‘ relatesis: particularly useful for
peak that occurs precisely at'the instant'of zero
increasing the accuracy with which control im
pulses are appliedr'to' such a' switching unit.
cross-over of the original wave. ' This sharp peak
undifferentiated wave occurs between a’ pair of
However, my invention is not limited to this par- ,
differentiated. wave: terminals. which are con
nected to one‘. of 'ther electrodes'of the‘ current
ticular application nor to the particular appa
ratus shown and described:
The control impulses ordinarily‘ta‘ke the-.form
controllingi device.
The-second circuit between the'said intermedi~
of single cyclesv of voltage ?uctuations such as
ate terminals and the-current-controlling device
might: be“. produced by‘ a magnet passing 3, our 50 includes an- integrator'which produces a voltage a
rent-producing coil‘ or‘ a device making and
continuously proportional to the instantaneous
reaking. aninductive circuit in proximity to such
a coil. In order to. produce high precision of
operation of‘ the switching: unit‘, it is desirable
time integral of the negative loop of the input’
This‘ integrated wave appears between
a pair of integrated‘ wave terminals‘ which. are
that‘t'he switching unit be actuated-at the precise 55 connected‘. to‘ the second control. electrode. of the
current-controlling device. The constants of the
integrator are so chosen or so adjusted that for
a control impulse of predetermined time dura
tion and amplitude the integrated wave will be
come sufficient in amplitude just before the in
stant of zero cross-over of the original wave to
raise the potential of the second control elec
trode of the current-controlling device to the
value preparing it for the passage of current
when the potential of the ?rst control electrode
reaches the requisite value. Accordingly for the
desired input impulses the current-controlling
input terminals l1 and I8. The mid point 29 of
the potentiometer resistance is grounded.
For amplifying the desired impulses or control
signals appearing across the input terminals l1
5 and I8 and substantially eliminating line to
ground noise, a special amplifying circuit 2! is
provided. The ampli?erll has output or load
terminals 22 and 20 (the latter being the common
ground) which represent intermediate terminals
of the impulse transmitting apparatus of the pres
ent application. Sets of terminals are shown in
various parts of the apparatus for convenience in
device becomes conducting in response to the
describing the operation and are referred to as
sharp peaks produced at the differentiated wave.
intermediate terminals; but it will be understood
that such terminals need not necessarily be
brought out in the actual apparatus except for the
purpose of checking the operation thereof by
terminals and transmits an impulse of like sharp-v
ness to the control terminals of the switching
A better understanding of the invention will
be afforded by the following detailed description
means of a suitable voltmeter, oscilloscope, or the
' considered in connection with the accompanying
For converting the ampli?ed input impulse at
drawings, and those features of the invention
which are believed to be novel and patentable will
be pointed out inthe claims appended hereto.
the terminals 22 and 20 into a sharp peak occur
ring precisely at the zero cross-over point of the
input wave, a circuit is provided including a clip
per 23 and a di?erentiator 24. The clipper 23 is
connected across the intermediate terminals 22
and 29, either directly or indirectly. In the ar
General description
In the drawings Fig. l is an electrical circuit
ment of my invention, and Fig. 2 is a set of graphs
rangement shown an'ampli?er 25 is interposed.
The di?erentiator 24 is interposed between the
illustrating the principle of operation of the appa
clipper 23 and a pair of terminals 26 and 21 re
ferred to as di?erentiated wave terminals, the
diagram schematically representing one embodi~
terminal 21 being shown as grounded. Conse
‘ In the drawings I have shown an impulse trans
‘ quently, in the arrangement shown the terminal
mitting circuit or system utilized in conjunction
21 is electrically connected to the grounded point
with a switching unit I l for controlling the appli
2c of the input potentiometer 19, which serves also
cation of high speed counting impulses from a
cycle generator l2 to a cycle counter 53. The 35 as one of the output terminals of the ampli?er
2!. Preferably an ampli?er 28 is interposed be
present application does not relate to the elements
tween the clipper 23 and the differentiator 24 and
H‘, l2 and I3, and these are represented sche~
an ampli?er 29 is interposed also between the
matically by rectangles. The cycle generator l2
differentiator and the differentiated wave ter
mayibe any source of impulses of adequate fre
minals 26 and 21.
quency and constancy. The cycle counter l3 may
An integrator 32) is interposed between the
be any cycle counting apparatus adapted to the
intermediate terminals 22 and 20 and a pair of
counting of impulses of the frequency produced
integrated wave terminals 3! and 21, the latter
by the cycle generator l2 and may take the form,
being shown as grounded and therefore common
forv example, of the devices disclosed in my co
to the second differentiated wave terminal. Pref
pending applications, Serial No. 400,075, ?led
June 2'7, 1941, and Serial No. 388,820, ?led April I erably the ampli?er 25 is interposed between the
integrator 30 and the terminals 22 and 20 and
11, 1941. The switching unit ll may be any
another ampli?er 32 is interposed between the
device which may be actuated in response to con“
integrator 30 and the integrated wave terminals
trol impulses so as to: be turned “on” and “off,”
or become conducting and non-conducting ,in 50 3| and 21.
For controlling the application of an actuating
response to successive control impulses so as to
voltage of the shape appearing between the differ
pass counting impulses from the cycle generator
entiated wave terminals 26 and 21 to the ?nal out
II to the cycle counter l3 during the interval
put terminals 14 and I5 serving as control ter
between two successive control impulses. The
switching unit may take the form, for example, 55 minals for the switching unit H, a current-con
trolling device 33, arranged as a noise reiector, is
shown in my parent application, Serial No.
provided. v'I‘he current-controlling device 33 is so
419,035, ?led November 13, 1941. If the frequency
constructed that it passes the differentiated wave
of the cycle generator I2 is accurately known, the
appearing between the terminals 26 and 2'! only
cycle counter l3 may be employed for measuring
the time interval between two successive control 60 when the voltage between the integrated wave
terminals 3| and 21 exceeds a predetermined
impulses applied between the control terminals 14
value. If desired, an ampli?er 341K135’ be inter—
and I 5 of the switching unit I i.
posed between the current-controlling device 33
' 'The control impulse terminals Ill and I5 are the
and the ?nal output terminals 14 and I5.
?nal output terminals of the impulse transmitting
arrangement described in the present applica
Noise limiting ampli?er 21
tion. For receiving control impulses from a
The ampli?er 2| comprises two stages of push
source (not shown) a pair of insulated con
pull connected electric-discharge. devices which
ductors I6 is provided which may be connected
may be of the three element vacuum tube or-tri
directly or coupled indirectly to a pair of input
terminals ll and it. Preferably, for permitting 70 ode type. The ?rst stage comprises a pair of tri
odes 35 and 36 and the second stage comprises a
adjustment of the minimum voltage of control
pair of triodes 31 and 38. Each triode has an
impulses which are to be passed by the impulse
anode, a cathode and a control electrode, desig
transmitting circuit, an adjustable gain control
nated by the customary symbols. The cathodes
[9, in tlie‘form of a potentiometer, is interposed
between the input lines of conductors l6 and the 75 of the triodes 35 and 36 are grounded through
preferably has‘ a?lterj circuit 25' interposed be!
a cathode impedance. 39 and the control elec
trodes of the triodesx35 and 36 are; coupled to the
tween ‘its anode resistor and the, positive terminal
input terminals I1 and 18 in such a. manner that
3+ of. the source. 46.
the control electrodes have opposite polarities.
For example. the control electrodesmay be con
Clipper 23
nected to the enkisiof~ a resistor 40; an intermedi
The clipper 23‘, as shown. takesthe form of a
pair of‘ rectifying elements-.68. .and El having
anodes82 and 63,, and cathodes; 64 and i3l5Zrespec;
tively..> Thev rectifying elements 5!! and “may be
ate point 46’ of. which is connected to an inter
mediate point of the cathode impedance39, and
coupling‘ condensers 4 I‘ and 42 may be interposed
between the input terminals ll and I8 and the 10 vacuum tube diode recti?ers such as type 6H6‘,
for example. The diodes have electrodes: of‘ op
ended‘ the resistor 48. If’line to ground noises .
posite polarity in effect connected together.
of all frequencies are to be attenuated, the oath; »
That is, the anode 6:2 of one diode andthezcath
ode impedance 39 may take the form of a resis
ode 65 of the other diode are connectedto an in‘
tor. For increasing the attenuation at higher
frequencies the impedance 39-. may be madein 15 termediate terminal 65 and the remaining two
electrodes 63 and 64. are grounded or connected
ductive, and for relatively increasing- the atten
to another terminal through biases of opposite
uation at lower frequencies the impedance 39
polarity. Use of an independent biassourcegives
may be made capacitive'in character. The tri
least erratic action. However, one of the exist
odes 35 and 36 are energized from a terminal“
through a pair of anode resistors 44 and 4.5,
20 ing. biases may be. employed. In the arrange
ment shown the bias ‘voltage sourceconsists of
The triodes 3‘!v and 38 are connected in a man
a biasing cathodel resistor 51 connected in. the
ner- somewhat similar to the triodes 35 and 36
cathode lead of the ampli?er 28. ‘The resistor
having their control'electrodes coupled to the
81 has a terminal 68 at a datum potentialv repre
anodes of‘ the triodes- 35 and 36- and- being ener
senting theUa-verage potential of the electrodes
gized from the terminal 431 through a pair of
63 and 84. of the clipper 23, has a terminal: 69 of
anode resistors. One of- the anodes, for exam
ple, the anode'of the triocle 31 is connected to
higher potentialthan the terminal 68 anda sec
the terminal 22 which serves as one of the inter
ond terminal 10 at a lower potential than» the
mediate terminals of the‘ impulse transmitting
terminal 68. The diode cathode 64 is connected
apparatus. The stage 3T—-38 of the ampli?er 2| 30 tothe terminal 59 and the diode anode 63- is
produces further signal ampli?cation and line
connected to the terminal‘ 19 which in the‘ ar
rangement illustrated is at ground potentiaI;
to-ground noise attenuation.
_ In order to obtain faithful ampli?cation of
The by-pass condensers ‘H and- ‘!2 are connected
very weak signals applied to the terminals [1, [9,
to the resistor 61 as shown.
the terminal 43 is preferably connected to a suit
able" source of closely voltage~regulated direct
The clipper 23- is coupled to the terminal 59
of the ampli?er 25 through’ a. resistance-capac
current consisting of‘ a unidirectional current
source 47‘, a ballast resistor 48~and a ?lter choke
ity circuit including a‘ condenser 13, a resistor
14 between one plate of'the condenser and? the
49 connected in series to the terminal '43- and
clipper terminal 66, and a resistor 15 connected
with a ?lter condenser 59 connected'between the 40 between the condenser 13 and the clipper terminal
terminal 43 and the ground terminal. For voltage
68, the second plate of the condenser ‘53 being
regulation a pair of voltage regulator tubes such as
connected to the terminal 59 of the ampli?er 25.
neon tubes may be connected between the ground
The potential differences between- the terminals
terminal and the common terminal 53 of the re
69 and 68 and between the terminals 68 and 18
sistor 48 and the choke 49. A resistor 54' may be
are so chosen that the maximum voltages between
connected across one of the tubes, e. g., the tube
the terminals 68 and 66 will be considerably less
52, in order to insure that the other tube, viz: 5|,
than the maximum deviations from the average
will break down ?rst when voltage is ?rst applied
voltage of the terminal 59, so that a square
from the source 41. Consequently, the voltage
topped ‘relatively steep-sided wave will be pro
of the source 4‘! need not exceed that vsufficient to
duced between the terminals 68 and 66, which has
a narrow sloping portion in relation to the time
break down one of‘the tubes 5| and 52, which .
have a considerably lower operating voltage at
period of the. wave.
which they hold the output voltage. It will be
The ampli?er 28 may bean ampli?er of con
ventional type comprising an- electric-discharge
understood that the resistor 54 is not a voltage
dividing potentiometer of negligible conductance
but a current-carrying element‘ which is capa- '
ble of causing the tube 5|‘ to break down.
The ampli?er 25
The ampli?er 25 may take the'form of a con
tube represented as a screen ‘grid vacuum tube or
tetrode with a cathode 1'! connected to the bias
resistor 61, a control electrode 18 connected to
the clipper terminal 65, a screen grid 19 'con
nected to a point at a suitable potential ina-con
60 ventional manner andian anode 80 connected in
ventional electric discharge device, being shown,
series, with an anode resistor B! to the positive
terminal of a source of anode potential which may
be the positive terminal B+- of a common source
46. The point 68in the cathode bias resistor 6'!
tor 55. The tetrode 25 has a control electrode 51 1 I serves as the point of datum potential for the
'asa tetrode screen-grid vacuum tube with a bias
resistor 55 connected in its cathode lead and a
by-pass condenser 56 connected across the resis
resistance-capacity coupled to the output ter
mlnal22' of the ampli?er 25 and has a screen
grid 58 maintained at a suitable potential in a
conventional manner with conventional by-‘pass
condensers connected thereto. The ground ter
minal and a terminal 59 connected to the anode
of the ampli?er tube 25 serve as a second pair of
intermediate terminals for the impulse transmit
ting apparatus. The ampli?er 25 may be ener
gized by a common anode.» voltage source. 4,6,;but
clipper 23, and the ampli?er control electrode‘ ‘I8.
Dijferentictor 24
The di?'erentiator 24 comprises a resistor 82
of relatively small resistance connected in series
with a condenser 83 of relatively small capacity
between a ground terminal 85v and the anode ter
minal 80 of the ampli?er 28 serving as another
pair of_,intermediate terminals of the impulse
transmitting circuit. If desired another relatively
low-resistance current limiting resistor 84 may be
connected in series between the resistor 82 and
the condenser 83 for Voltage division; Thecomé
mon point 85 of the resistors 82 and 84 together
with the ground terminal 86 serves as another
series conection of a resistor 96 of relatively large
resistancefconnected between the terminals 59
The output terminals 92 and 9| of the in
tegrator-30 serve as the input terminals of the
pair of intermediate terminals. They may be used
ampli?er 32, which'may be an electric discharge
asYa pair of differentiated ‘wave terminals but
device of conventional type shown as a screen
grid vacuum tube or tetrode with a control elec
preferably the ampli?er 29 is interposed between
the terminal 85 and the differentiated wave ter
minal 2B.
trode connected to the output terminal 92 of
10 the integrator 30 and with a cathode grounded
- ‘The ampli?er .29 may be a conventional electric
in 'a conventional manner through aby-passed
discharge tube such as a triode vacuum tube.
Preferably it is designed and connected so as to
bias resistor.
The ampli?er 32' has a load terminal 91 con
be zero Ibiased and grid limited for cutting off / nected to its anode .which is resistance-capacity
negative peaks to avoid the necessity for accu 15 coupled to the integrated wave terminals 3| and
2'1, the latter being a grounded terminal;
rately controlling the amplitude of the input sig
nal and to permit sharpening the signal in suc
Noise rei'ector 33
cessive vacuum tube stages by small-time-con
device 33 is shown as
stant resistance-capacity couplings. A Class B
tube such as one-half of a type 6N7 may be em 20 taking the form of a plural grid electric dis
charge device such'as a BL’? pentagrid vacuum
ployed, e. g., which will stand having grid and
tube, for example, arranged as a mixer ampli?er.
cathode tied together through a resistor. The
The ampli?er 33 has ?ve grids customarily desig
characteristics are such that the tube operates
nated by the numbers 1 to 5 consecutively from a
between cut-off and the e?ective‘ plate-current
saturation that results from the rectifying effect 25 cathode 98 to an anode 99. The #5 grid iscon
nected to the cathode 98 to serve as a suppressor
of the grid which tends to limit its rise in poten
grid in the conventional manner and the #2 and
tial. As shown it has a grounded cathode, and
#4 grids are connected to a point of suitable
an anode connected in series with an anode re,
intermediate potential in a conventional manner
sistor 8'! to a positive current source terminal,
whichmay be the terminal B+ of the common 30 to serve as a shield for the #3 grid. The #1 and
#3 grids are utilized as independent control elec
source 46. It has a control electrode or grid 33
trodes, the #1 grid being connected to the .
connected to the terminal 85 of thedifferentiator
differentiated wave terminal 29 and the #3 grid
24. Myinvention is not limited to speci?c con
being connected to the integrated wave terminal
stants and relationships. However, when using
a plate current source 46 of 300 volts, I have ob 35 3|. The cathode 98 is connected through a bias
resistor I00 to the ground terminal 21. Suitable
tained satisfactory operation of the tube 29 by
making the capacity of the condenser 83 one
hundred zmicromicrofarads, ‘and the resistances
of the resistors 82 and 84, one hundred thousand
by-pass condensers are provided as shown. The
anode 99 is connected in series with an anode
resistor IOI to a positive terminal of a source
and ?ity'thousand ohms respectively, when the 40 of anode voltage which may be the positive
terminal B+ of the common source“. The
time duration of negative impulses applied to the
constants of the circuit of the ampli?er 33 are
di?erentiator between its input terminals 80 and
so chosen that it will conduct current and trans
86 is anything from about thirty microseconds
to a few hundred microseconds or more.
The ampli?er 29 is resistance capacity‘ coupled
to the di?erentiated wave terminals 29 ‘and-21
through a condenser 89 and a resistor 90 which
have a sufficiently small time constant to preserve
the steepness of the differentiated-wave appear
mit an impulse through its load terminal I02
D connected to the anode 99 only when both the
potential difference between the differentiated
wave terminals 26 and 21 and the potential di?er
ence between the integrated wave terminals 3|
and 2‘! exceed predetermined values. These
ing between the ‘terminals 85 and86~across the O! O values are respectively avalue below that which
differentiator resistor 82.
Integrator 30
g _V
r '_
r The integrator 30 comprises iundamentallya
resistance capacity circuit of relatively large time
constant which in its simplest form might consist
the differentiated wave between the terminals 26
and 21 is expected to attain in response to a
desired signal impulse, and a value less than the
maximum amplitude of the integrated wavepro
duced between the terminals 3| and 21 by a sig
nal impulse having the minimum e?ective period
for impulses which are to be transmitted through
of a relatively large condenser and a relatively
the apparatus’? In this manner the device 33
large resistor connected in series between the in
serves as a noise rejector. The device 33 may be
put terminals 59 and a ground terminal 9 I vwhich
comprise the load terminals of the ampli?er 25; 60 regarded as a coupling device controlled by the
integrated wave at the terminals 3| and 21 for
the output terminals 92 and 9| of the integrator
selectively coupling the differentiated wave
being terminals of the condenser. However, in
terminals 2'6 and 21 to the load terminals I02
order to provide for adjustability of the minimum
and 21.
effective period of signals to‘ which the signal
transmitting circuit will respond, the, condenser 65 For “zero” and “in?nity” end points of the
range of minimum effective periods of input
connected between the terminals 92 and 9| is
signals to be passed, the movable contact 94
made adjustable. , It takes the form, for example,
may have mechanically connected‘ thereto a
of a plurality of condensers 93 each having a dif
second movable contact I03 cooperating with a
ferent capacity, grounded on one side and con
nected on the other side to stationary contacts 70 plurality of stationary contacts all of which are
grounded except the last, which is designated by
adapted to cooperate with a movable contact 94
the numeral Hi4 and is connected to the cathode
connected to the integrator output terminal 92.
98 of the ampli?er 33. The movable contact I03
Also, to facilitate providing adjustability in the
is connected to the integrated wave terminal 3|
responsiveness of the impulse transmitting c'ir
in series with a resistor I05.
cuit, a. coupling condenser 95 is interposed in a
Serial No. 419,035, ?led Novemberg13, 1941, which,
The movable contacts 94 and I03, together
with the stationary contacts form, a selector
is prevented from responding to more than two
signal cycles unless reset. Referring to curve E10
again, it will be observed that there may be some
ragged voltage ?uctuations I I3 which are irregu
switch P for adjusting the minimum effective
period of signal impulses to be passed. For the
end points “in?nity” and “zero” respectively of
the switch for testing or checking purposes, two
lar in wave form and occur before or after the
additional grounded stationary contacts MBA and
initiating signal II I and which might cause false
operation of the switching unit ‘II if the switch
H163 are provided which cooperate with the mov
able contact 94. In the “in?nity” position no
signals are passed and in the “zero” position all
ing unit II were permitted to respond to such
spurious voltage ?uctuations IIS. Owing to the
signals are passed.
fact that such spurious voltage ?uctuations are
usually of ragged character and would produce
a disagreeable sound which if the signal output
‘The ampli?er 34 may also be an electric dis
charge device of conventional type, being shown
as a triode vacuum tube with a grounded cathode‘
were converted into acoustic vibrations, they are
and a control electrode, resistance-capacity cou 15 frequently referred to as noise.
pled to the load terminal I02 of the ampli?er
33. In order to preserve the sharp character
of the impulse signal transmitted ‘through the
Signal sharpening
The problem of making the switching unit II
ampli?er 33, this coupling circuit is designed
respond precisely at the instant when the initiat
with a relatively low time constant comprising a 20 ing signals I II and ‘I12 cross theihorizontal axis
relatively small condenser I0‘! and a relatively
or zero point will ?rst be considered. In order
to steepen the ‘portion of the wave in the vicinity
low-resistance resistor I08 in series, with an
additional relatively small resistor I09 inter
of the ‘zero cross-over point, it may ‘first be con-'
siderably ampli?ed as represented schematically
posed in series, if desired, for dividing the po
tential applied to the control electrode of the
by ‘the curve E11. If desired the ampli?cation
ampli?er 34. If desired the ampli?ers 34 and 29
maybe even greater thanthat shown by the scale
may form two parts of a double triode vacuum
of the curves since the peaks are to be elimi
tube as shown; Preierably‘the ampli?er 34 also
nated. The function of the clipper 23 is illus
has‘zero grid bias, and the circuit constants are‘
trated by the curve E12. ‘It will ‘be apparent that
such that the input signal swings the grid or
. a greatly magni?ed wave such as E11 although
contro1, electrode well ‘beyond cutoff to produce.
a sharp pi?se of positive polarity and having an
originally‘ somewhat resembling . a ‘sinusoidal wave
form ‘will become a square topped wave with a,
amplitude and width essentially independent of
very nearly'perpendicular cross-over portion II4
the slope of the original signal at zero cross
as shown in curve E12,,if the amplitude is limited
' to a ?xed value ‘relatively small in comparison
The ampli?er 34 has its anode connected in
with the original peak amplitude. The trans
series with an anode resistor to a‘positive termi
mission of such a wave through a low time con
nal from a source of anode potential in any con
ventional manner and the anode is connected to
stant’ circuit such as the d'i?erentiator 24 re-_
coupled in any conventional manner to the ?nal
output terminals I4 and I5 which serve as the
in curve E31.
sults in the production of steep voltage impulses
a load terminal III! which is resistance-capacity 40 atthe vertical portions of the curve E12 as shown
After such a wave is transmitted
through the ampli?er 29 it is further ampli?ed,
control terminalss of the switching unit II.
the negative peaks are cut off, and onlythe am
pli?ed positive peak E14 remains. It will be un
Operation in general
gr. ;m derstood that in resistance-capacity coupled
The purpose to be accomplished by the impulse
vacuum tube circuits having anode resistors or
transmitting arrangement shown in Fig. 1 and
impedances the wave is ordinarily inverted by U
the principle of operation will be understood more
each stage, i. e. has the polarity reversed because
readily from the graphs of functional wave forms
anode voltage rises when grid or control elec
shown in Fig. 2. Each of the graphs of Fig. 2 50 trode voltage falls, and vice versa. However, the
represents a voltage wave and the waves are
connections and characteristics of the tube 29
designated by the symbols E10 to ‘E19, inclusive,
are .such that positive voltages ‘applied to the'
which symbols are also applied to the points in
control grid 88 have relatively little effect. Since
the diagram of vFig. 1 at which voltages of such
the tube employed is of the type uninjured by
wave form appear. The apparatus for produc 55 positive grid voltages, thegrid may be connected
ing the input signals which are intended for
actuating the control terminals I4 and I5 of the
switching unit I I is not a part of the present
invention and, therefore, need not be described.
It will be assumed that an input signal of the
wave form shown in E10 is received through the
conductors I6 and applied to the input terminals
I1 and I8.
The potentiometer I9 is set at a
value for controllingthe minimum amplitude E
of input control signals to which the apparatus
is to be made responsive.
Referring to Fig. 2 it will be seen that the
curve E10 includes a voltage ?uctuation I I I com
prising one cycle which serves as an initiating
signal, and a second single-cycle voltage ?uctu
ation II2 which serves as a terminating signal.
These two signals are .for ?rst turning the switch
ing ‘unit on and then turning it oh‘. If desired
the switching unit II may be of the type de
aforesaid “Copending application
to the ‘cathode through a resistor to give a zero
bias. The tube is in e?ect saturated at zero grid
potential because the grid recti?es the input sig
nal without forcing the anode potential to change
appreciably. The resistor 84 limits the grid cur
rent. Consequently, no appreciable change in
anode-cathode discharge current is produced by
the positive loops of the differentiated wave be
tween the terminals 8§—85. In this manner the
negative loops in the output wave at the tube
anode are out 01f. The negative loops of the
differentiated wave between the terminals 85 and
85, . however, drive the grid negative and the
anode positive. The constants are so chosen that
the grid 88 is driven well beyond cuto? so that
the anode is driven sharply positive. The small
timeconstant of the resistance capacity coupling
circuit 88-90, further sharpens the wave and
results in a sharp positive peak between the dif
ferentiated wave terminals 26 and 27, there be
ing but a single peak owing to the action of the
tube 29 in cutting off the negative peaks. It is
therefore unnecessary to have su?cient time
constant in the coupling 89-90 to reproduce the
wave without overshoot, which would be neces-.
impulses of shorter time durationhas. the effect
of decreasing the width, measuredin the horizon?
tal direction, of the lobe of the curve E15, so that.
the desired sharp impulse of curve E14 maybe
passed; but any noise fluctuations shortlybefore
or after the desired impulse will have no. effect. ,.
sary if the two positive peaks (negative in the
It will be seen accordingly that after the volt—.
output) of the wave applied to the control grid
age of the wave form shown in curve E14 has been
88 had been retained. Successive further sharp
transmitted through the current-controlling de
ening of the wave in the stages 33 and 34 is thus
possible by use of low-time constant coupling 10 vice 33, it will take the waveform
curve E16 from which the noise ?uctuations have
circuits. Comparing the peaks of curves E10 and
been eliminated. Owing to the di?iculty of‘ ac
E14 it will be observed that a very steep sharp peak
curately portraying the minute deviations in noise
of high amplitude and exceedingly short dura
voltage to the scale used in Fig. 1, no’attempt
tion is produced at the instant that the signal
has been made to show the instant-to-instant
III or II4 cross the zero point. Consequently,
variations accurately in the successive trans
the instant of actuation of the switching unit II
formations of the curve I I3 in the graphs E-IB
is precisely ?xed.
to E—I5 and these curves "are‘to be considered
Noise rey‘ection
merely as roughly indicative of the general na—
It will be evident that the various amplifica 20 ture of the noise. It will be understood that
the switching unit II is so designed that a sharp
tions involved in the operation of sharpening the
impulse I I I’ representing anv initiating signal
initiating signal unit I I will also have the effect
raises a control potential therein and a sharp
of amplifying the noise voltage fluctuations II3.
impulse Il2"representing the terminating signal
Accordingly, in order to guard against spurious
operation of the switching unit I I, means are 25 lowers the control potential therein as represented
by the curve E11. The counting impulses produced
provided for preventing the current-controlling
by the cycle generator I2 are represented sche
device 33 from passing a signal in response to
matically by the curve E13 (shown with less than
steep voltage ?uctuations such as those shown
usual frequency for clarity), and the’counter im
atvII3. For this purpose wave forms such as
shown in curve E15 are derived from signals ,I II 30 pulses transmitted by the switching unit I I from
the generator I2 to the cycle counter I3 are rep
and H2 for energizing the control electrode or
#3 grid of the ampli?er 33 during a period with
resented by the curve E19. It vwill be observed that
during the time interval between the peaks III’
in' which the sharp signal impulse of E14 is to act.
and H2’ the. counter impulses of the curve E19
The voltage of the curve E15 is the negative inte
gral with respect to time ‘of the voltage of the 35 are supplied to the cycle counter I3. An indica
tion’ of the number of such cycles produced by
signals III-and H2; The ?rst half of a loop of
the counter I3 serves therefore as an indication
the curve E15 between the points H5 and H6 is
of the time interval between the initiating signal
the integral of the negative loop'I ll of the ini
tiating signal III.
Geometrically it represents
the area of the loop I H. The instantaneous value 40
of the vertical distance from the horizontal axis
to a point on the curve E15 represents the time
integral at that instant of the initiating signal
III. The constants of the mixer or multi-grid
current-controlling device 33 are so chosen that
the mixer passes the sharp impulse E14 only when
the time integral of the negative lobe of the in
put signal voltage approaches the value
and the terminating signal.
Circuit testing
For testing the noise pick-up of the line I6 and
checking the operation of the apparatus the end
points IIiIiA and IDBB oi the selector switch P
may be used. When the contacts 94 and IOBA
are together, the integratoroutput terminal 92
remains grounded, the integrated wave between
theterminals 3i and 21 remains zero, and the tube
33 has its #3 grid permanently biased off so that
no signals can pass. This. corresponds to in?nite
condenser capacity in the selector P or "accept
where E is the minimum amplitude of an input
signal which is to be accepted by the circuit and
ance” only of signals having an in?nite time dura-'
tion. On the other hand, when the contacts 94
P is the minimum effective time duration of an
input signal which is to be accepted by the ap
paratus. The value of E may be adjusted by the
potentiometer I9 and the value P may be ad
justed by the condenser selector switch P.
Adjustability of the degree of acceptance of the
circuit is desirable for the reason that the switch
ing unit I I is intended to be used for response to
control impulses under widely diiTerent conditions
and IIZSB are together, and likewise the contacts
I33 and IN, the .tube 32 remains biased off, ‘but
the potential of_the‘#3 control electrode of the
tube 33 is raised to cathode potential by connec
tion thereto through the resistor I05, and any
signal on the #1 grid is passed. This corresponds
to acceptance of input signals of the “zero” mini
mum effective period. This. setting of the selector
switch P may be used with a noise-free line to
of operation. For example, when the switching
unit islused under conditions when the initiating
signal and the terminating signal will each be
of short duration and one closely following the
other, it is necessary to adjust the apparatus for
acceptance of input signals of shorter time dura
tion thanv when the initiating signal and the ter
minatingsignal are separated by long time inter
avoid change of setting for input signals of diiTer
ent minimum effective periods.
In order to test the accuracy of the impulse
transmitting apparatus and also the elements
i2, H and. I3, a test signal source may be .pro
vided. As illustrated in Fig. 1 I provide’a double
pole double-throw switch I I‘! with a pair of mov
able blades connected to the line I6 leading to the
vals. In this manner the apparatus may be so
adjusted as not to respond to any noise impulses
occurring before or between the two successive
loops of the curve E15. It will be understood that
impulse transmission system input terminals I1
and I8. The switch I I‘! has a pair of stationary
contacts H9 connected to conductors I20.such
a telephone line, e. g., leading from a regular
adjusting the selector switch P for acceptance of 75 source of control impulses (not shown), ands.
second pair of stationary :contacts I2'I connected
to a test signal source.
The test signal source comprises a pick-up coil
I22 which is a current-conducting coil connected
to the switch contacts I2I and which is mounted
near the periphery of a rotatable ‘disk I23, For
producing a magnetic flux to react inductively
have the ‘effect of balancing the signal :volta'ges
applied to the conductors I6 in case they should
be unsymmetrical with respect to ground. In this
case the lack of symmetry causes :su?icien‘t var
iation in current ?owingin the cathode‘resistor
39 to balance the signal voltages with respect
to the bias point-40' in‘the control electrodes of
on the pick-up coil I 22, a permanent magnet I24
is radiallyimounted at the‘ ‘edge ‘of the disk I23.
For driving the disk ‘I23 at a uniform speed
which may be held with great constancy, it is con
nected to a synchronous motor ‘I25 energized .by
an accurately constant frequency source of al
the'tubes 35 and 35.
such as a revolution counter and accurate clock,
a tachometer or an accurate "frequency meter 121
cover all such modi?cations and variations :as fall
within ‘the scope of my ‘invention which are
.I have herein shown and particularly ‘described
certain embodiments of .myinvention and "certain
methods of operation embraceditherein for the
purpose of explaining its practice :and showing
its application‘, but it :will be obvious toithose
ternating current I26. For'checking the speed
skilled in the art that many modi?cations and
of the synchronous motor 125 a suitable device, 15 variations are possible and I aim therefore to
is provided.
When it is desired to test the operation of
the control impulse transmitting .and cycle .
counting apparatus the switch H1 is closed in a
test signal position and the time interval be
tween two successive transits of the magnet I24
past the pick-up coil I22 is determined by cal
culation from the speed of the synchronous mo
tor I25 indicated by the frequency meter ,I2'I.
de?ned in the appended claims
I ‘claimofasthe
and desire
.1. Apparatus .for producing a sharp'si'gnal iim
pulse in response to a cycle of voltage ?uctuation
comprising a pair of input ‘terminals adapted 'to
have voltage fluctuations applied thereto‘, a‘de->
vice connected to saidterminals for amplifying
the ‘voltage “to steepen the portion'of the'volt'age
Theproper functioning of ‘the ‘apparatus may be
checked with the motor I25 running by connect
ing a cathode ray oscilloscope between ground
cycle at the zero cross-over point, said device
having two output connections, a pair of diode
recti?ers connected in parallel ‘with unlike elec
and the various intermediate terminals in suc
trodes together between the output connectionsro'f
the amplifying device, and a pair of output ter
minals for the apparatus-one o‘fthe diodes being
biased positively with .respect to :a datum poten
tial, the other being biasednegatively withre
cession such as the‘terminals 22, 59, 66, 80, 85,
26, 92, 3I, and III}, for observing the wave forms.
Line noise attenuation
The manner in which the ampli?er '2I elimi
nates line to ground noise from the v‘conductors
i 'spect ‘to a datum potential whereby "the voltage
wave applied thereto is clippedat the positive and
negative values corresponding to said lbiases'said
I20 and II 6 will be understood from a consid
eration of the operation of the degenerative cath
ode resistors, such as the resistor 39 associated
‘ minals by ‘a resistance capacity circuit .having'a
with the tubes 35' and 36. A genuine input sig
relatively small product ‘of resistance and capac
diode recti?ers being coupled vto said output ter
nal produces a potential difference between the
ity, said coupling circuit ‘including a ‘resistance
conductors I6 and likewise between the control
connected between the output terminals ‘and a
electrodes of the tubes 35 and 36. Accordingly
condenser connected between one of the output
the discharge current of one tube "is increased
terminals and one ofthe output connections of the
and that of ‘the other 'tubeiis decreased and an 45 amplifyingdevice, the second output terminal of
amplifying effect takes .place in a conventional
manner by reason of the fact that the increase
in current in one anode resistor 44 and a decrease
in the other resistor 45, or vice versa, produces a
the apparatus being connected 'to't'he second out
put connection of ‘the amplifying'device.
2. Adiscriminator for preventing ‘the response
of an impulse ‘responsive circuit to spurious volt-
potential difference between the two anodes 50 age variations referred .to as noise, ‘said apparatus
which is considerably greater than the difference
comprising a pair of .input terminals to which a
between the two electrodes. Since one vcontrol
voltage is adapted'toibe applied which is intended
electrode is raised in potential as much as the
to ?uctuate through one'cycle to represent each
other is lowered and likewise the anode current
genuine input impulse,v .a second pair of ‘ter
of one tube is raised as much as that of the other
minals vreferred to as differentiated wave ter
is lowered, there is no change in the current
minals, apparatus interposed between the ?rst and
second pairs of terminals for converting the in
put cycle of voltage ‘?uctu‘ationjinto a sharp volt
?owing in the degenerative cathode ‘resistor 39.
Consequently, the amplifying ratio of the tubes
is unchanged and the input signal is fully am
pli?ed. However, if line to ground noise were
to be picked up by the conductors I20 or IIB,
both control electrodes of the tubes 35 and 36
would be raised or lowered together and the cur~
age impulse, a third pair of terminals referred
to as integrated wave terminals, a resistance ca~
pacity vcoupling circuit interposed between said
input terminals and said integrating tenminals,
said coupling circuit having a relatively ‘high prod~
rent ?owing in the degenerative cathode resistor
not of resistance and capacity, including a con
39 would be varied causing a variation in the i denser connected between the integrated wave
cathode potential nearly ‘equaling "the variation
terminals and a resistor connected between one
in control electrode voltage in each tube. Con?
of said integrated wave terminals and one of the
sequently the residual grid-cathode voltage,
input ‘terminals, the remaining input terminals,
greatly reduced, produces very little output or
the ‘remaining integrated wave terminal and one
load voltage. In this manner, line to ‘ground -' of the differentiated Wave terminals being con
noise is attenuated, whereas the desired input
' nected together electrically, a fourth pair of ter—>
signals appearing between the conductors l6 are
minals referred to as output terminals, and a‘
ampli?ed. This action is further enhanced by
coupling device and mixer interposed between the
the second stage of tubes 31 and '38. The con
diiferentiatedi'wave terminals and the output ter
nections of the tubes 35 and 36, 31 and 38 also "
minals on the one hand and ‘between the inte-v
gratedwaveterminals andlthe output terminals
onthe other hand, said coupling device having
the characteristic of passing an impulse only
whentthe voltages applied thereto exceed prede
termined values, whereby the reception of a gen
uine signal prepares the coupling device for the
passing of the sharpened genuine wave appearing
at the di?erentiated wave terminals by applying
entiated wave terminals and the other of which is
connected to the integrated wave terminals
whereby the sharp impulse at the diiierentiated
wave terminals is ‘passed through the mixer only
when the amplitude. of the integrated wave
exceeds a predetermined value so that a noise
voltage and other spurious voltage variations of
improper time duration fail to prepare the mixer
for passage of an impulse, whereby such noise‘
an integration of the genuine wave to the inte
grated wave terminals but spurious voltage fluc 10 voltages and spurious voltage ?uctuations are
cut oil from the output of the mixer.
tuations are of insu?icient time duration per cycle
6. Apparatus for transmitting voltage ?uctua
tolproduce an integrated wave of sufficient value
applied between a pair of conductors and
to prepare the coupling device for impulse trans
substantially eliminating line to ground noise or‘
l -3._A discriminatingimpulse transmitter com 15 spurious voltages ‘picked up between said con
ductors and ground, said circuit comprising a pair
prisinga pair of input terminals to which a volt
of input terminals to which said conductors may
age ?uctuation is adapted to be applied as an
be coupled, a pair of three-element discharge de-'
input impulse, a second pair of terminals referred
vices connected push pull, a ground terminal and
to ‘as differentiated wave terminals, appa'ratusin
terposed between the ?rst and second pairs of 20 an energizing source terminal between which a
source of anode potential may be applied, said
terminals for converting. the input cycle of volt
electric discharge devices each having an anode,
age ?uctuation into a sharp voltage impulse, a
a cathode and a control electrode, a coupling be
third pair of terminals referred to as integrated
tween said input terminals and said control elec
wave-terminals, a fourth pairof terminalsre
trodes for applying a potential difference between
ferred to as output terminals and a coupling de
said control electrodes responsive to the poten
vice interposed between the differentiated wave
difference between said input terminals, an
terminals and the output terminals on the one
impedance connected between said cathodes and
hand and between the integrated wave terminals
said ground terminal, a pair of anode impedances
and the output terminals on the other hand, said
coupling device having the characteristic of pass 30 each connected between said anode source ter
ingan impulse only when the voltages applied
thereto exceed predetermined values.
minal and one of said anodes, and an output ter
input terminals and the output terminals sepa- '
control electrode potentials to produce variation
minal connected to one of said anodes, whereby
the output voltage between said output terminal
4. A. discriminating impulse transmitter com
and said ground terminal ?uctuates in response
prising a pair of input terminals to'which a volt
age ?uctuation is adapted to be appliedcas an 35 to variations in voltage applied between said input
terminals with line to ground noise eliminated,
' input impulse, a second pair of terminals re
said desired input voltage having the effect of
ferred to as integrated wave terminals, an inte
raising the potential of one control electrode and
grating device interposed between the input ter
lowering the potential of the other at any given
minals and the integrated wave terminals for
producing a wave having an amplitude continu 40 instant to maintain substantially constant cur
rent in the cathode impedance and consequently
ously proportional to the integrated value of a
substantially constant ratio of ampli?cation
wave applied to the input terminals, a third pair
whereby line to ground noise produces simul
of terminals referred to as output terminals, and
taneous variation in the same direction of the
a coupling device interposed between the said
rately from said integrated wave terminals and
said integrating device, said coupling device hav
ing, however, a voltage responsive control ele
ment for rendering the coupling device effective
or ine?ective, said voltageresponsive element be
ing connected to said integrated wave terminals
for rendering the coupling device effective only
when the potential difference between the inte
grated wave terminals equals the integrated value
of waves of a minimum effective period which are‘
to be transmitted by the coupling device.
'5. A discriminating impulse transmitter com
prising a pair of input terminals to which a voltage
fluctuation is adapted to be applied as an input
impulse, a second pair of terminals referred to as
diiierentiated wave terminals, a clipper for con
verting the input wave into a square topped wave
with a relatively steep cross-over portion, a device
interposed between the clipper and'the differ
in current ?owing in the cathode impedance
whereby degenerative ampli?cation is introduced
and such line to ground voltage is attenuated.
7. A test impulse generator for an impulse
responsive device comprising a, rotating member
carrying a permanent magnet, a current-con
ducting coil mounted adjacent said rotating
member in inductive relation with said magnet
atone angular position of the rotating'member
and a substantially constant speed motor for
driving said rotating member with means for
measuring the speed of said motor whereby the
timing of electrical impulses induced in said
current-conducting coil by the motion of said
magnet may be compared with the measured
speed of the driving motor.
8. A wave converting circuit comprising a
three-element zero-biased grid-limited electric
discharge device with an anode energized through
voltage impulse at the differentiated wavev ter
an anode impedance, said device having a cathode
and a control grid joined by a resistor across
minals in response to the cross-over portion of the
clipped wave, a third pair of terminals referred
to as integrated wave terminals, a device inter‘
resistance-capacity wave-sharpening coupling be
entiated wave terminals for generating a steep
which a reversing polarity peaked wave is adapted
to be applied, a pair of output terminals and a
grated wave terminals for producing a wave hav-'
tween the electric discharge device and the out
put ‘terminals, said coupling having a relatively
ing , an amplitude continuously proportional to
small time constant, whereby the positive peaks
posed between the input terminals and the inte
of the wave applied to the said control electrode
the integrated value of a wave applied to the input
are relatively ineffective and the negative peal;
terminals, and a mixer having a pair‘ of control
electrodes one of which is connected to the diifer 75 drives the discharge device abruptly beyond cut-r
o? to transmit'a sharp positive peak of increased
a di?erentiation of the input wave applied to the
input terminals appears between the ?rst input
terminal and the intermediate terminal, and the
positive peaks of said di?erentiated wave have
relatively little e?ect on said electric discharge
device owing to its characteristic of being effec
tively saturated at zero grid potential by the rec
slope to the said output terminals.
9. A wave converting circuit for producing a
single steep positive peak at the zero cross-over
point of a cycle of voltage ?uctuation compris
ing a pair of input terminals to which an input
voltage ?uctuation cycle is adapted to be ap
tifying e?ect of the control grid tending to limit
plied, an intermediate terminal, a resistor con
its positive potential, but the negative peak of the
nected between the ?rst of said input terminals
and said intermediate terminal and a condenser 10 differentiated wave is inverted to form a positive
peak appearing at the anode of the electric dis
of relatively small capacity connected between the
remaining .inputterminal and said intermediate
charge device, the time constant or resistance
capacity product of said differentiating resistor
terminal, a grid-limited zero—biased electric dis
and condenser being small in relation to the ex
charge devicehaving an .anode, a cathode and-fa
pected time duration of negative input impulses
control grid, the resistance of said ?rst men
for permitting the control grid to return to within
tioned resistor exceeding the grid to cathode re
negative cut-o?’ potential and thus to restore the
sistance of said discharge device, an anode \r'e
anode potential to the initial value before the
sistor adapted to be connected in series between
end of the input impulse, thereby making the out
’ the anode and the positive terminal of an anode
put pulse duration and shape as well as ampli
voltage source having a negative terminal con
tude independent of input impulse shape and
nected to the cathode of the ‘discharge device,
said cathode being connected to the ?rst of said
input terminals and the control electrode being
connected to said intermediate terminal whereby
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