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Патент USA US2595048

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April 29» 1952
J. R. nEscH ETAL
îFiled March 20, 1940
11 Sheets-Sheet l
'Joseph R. Desch and
Robert E. Mumma
April 29, 1952
Filed Mai‘ch 20, 1940
11 Sheets-Sheet 2
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Joseph R. Desch and
Robert E. Mumma
Their Attorney
April 29, 1952
Filed March 20, 1940 Y
11 Sheets-Sheet 5
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Robert E. Mumma
Their Attorney
I April 29, 1952
Filed March 20; . 1940
11 Sheets-Sheet 4
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Robert E. Mumma
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April 29, 1952
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April 29, 1952
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11 Sheets-Sheet 7
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Robert E. Mumma
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ApriI 29, 1952
J. R. Di-:scH l-:rAL
Filed March 2o, 1940
11 sheets-sheet 8
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Robert El Mumma
Their Attorney
April 29, 1952
J. R. DEscH ErAL
Filed March 20, 1940
11 Sheets-Sheet 9
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Joseph R. Desch and
Robert E. Mumml
Their Attorney
April 29, 1952
J. R. DEscH x-:TAL
Filed March 20, 1940
11 Sheets-Sheet 10
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Joseph R. Dcsch and
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Their Attorney
April 29, 1952
J. R. DEscH Erm.
Fned March 2o, 1940
11 sheets-sheet 11
FIG. 10C #î 204 205"
Joseph R. Dcsch and
>Robert E. Mumma
Their Attorney
Patented Apr. 29, 1952
Joseph R. Desch and Robert E. Mamma, Dayton,
Ohio, assignors to The National Cash Register
Company, Dayton, Ohio, a corporation of Mary
Application March 20, 1940, Serial No. 325,040
136 Claims. (Cl. 23S-_61)
This invention relates to calculating machines
and more particularly relates to an electrical
calculating machine that functions to differen
tially accumulate items solely by the flow of elec
tric energy and without mechanical movement of
any parts.
In this novel calculating machine, selected
numerical data is entered by means of the dif
ferential action of electronic devices into an
means for entering data into a numerical ac
cumulator having electronic devices representing
denominational digits.
Another object of the invention is to provide
a calculating machine accumulator which has in
operation no moving parts of ponderable mass.
Another object of the invention is to provide
an accumulator of numerical data using elec
tronic devices capable of receiving, accumulating
accumulator comprising a plurality of denomi
nationally grouped electronic devices, the selec
tive operation of which devices during a plural
ciated with purely electrical phenomena.
ity of data-entering operations causes the ac
cumulation of data. The relative electric con
means for producing a selected number of elec
and storing such data at the high speeds asso
Another' object of the invention is to provide
dition of the electronic devices in the accumu- _
tric impulses in an electric circuit by operation
of a selected number of electronic devices.
lator, as pertains to their conduction or non
conduction' of electric energy, represents the
means to produce a diiîerentially-selected num
digit value of accumulated data, which electric
condition may be noted by observing the elec- _
tronic devices or sensed by an electro-mechanical
device for visual indication of the data. Neither
the diiierential action nor the accumulating ac
tion of the machine involves any movement of
the parts except for the flow of electric energy
therethrough. Data to be entered into the ac
Another object of the invention is to provide
ber of electric impulses at the extremely high
speeds associated with purely electrical phe
Another object of the invention is to provide
an accumulator for a calculating machine and
diiîerential means for entering numerical data
therein, said accumulator and differential means
cumulator may be derived from a denomina
having, in operation, inertia and time factors of
those negligible values associated with electrical
ticnally-arranged keyboard controlling the dif
ferential action of a set of electronic devices,
Another object of the invention is to provide
or the data standing on the visual indicator may
means whereby one group of electronic devices,
be entered directly into the accumulator elec 30 operated one at a time in sequence, may cause
tronic devices without the use of keyboard
the operation of another group of electronic de
vices one at a time in the operation sequence
The principal object of this invention is to
intervals of the Erst-mentioned group.
provide a calculating machine which is much
Another object of the invention is to provide
faster in operation than any such machine here
an accumulator of numerical data necessitating,
tofore known.
in entering diiïerential data or in withdrawing
Another object of this invention is to provide
accumulated data, no movement of the parts ex
a calculating machine which is practically noise
cept their electrons or ions.
less in operation.
Another object of the invention is to provide
Another object of this invention is to provide 40 means for transferring denominational carry
a calculating machine that can be manufactured
overs in an accumulator of numerical data
at lower cost than machines now known, be- ’
solely by an> electric impulse without physical
cause of the fact that accurate operation does
movement of any parts.
not depend upon the manufacture of parts to
Another object of the invention is to provide
precise and accurate dimensions, thus eliminat‘- `
means to enter data into the denominational
ing the factor which has contributed greatly to
orders of an electronic numerical accumulator
the high cost of manufacture of such machines.
in denominational sequence.
The _foregoing and other objects of this in
Another object of the invention is to provide
vention `are attained by providing an electrical
means for entering data into the denominational
calculating machine wherein selected data is
orders of an electronic accumulator of numerical
entered and accumulated solely by the flow of
data whereby the entry of carry-over data will
electric energy Without physical movement of
not interfere with the entry of the selected data
any parts, except starting and stopping devices,
and it is one of the principal objects of this in
vention to provide vsuch a machine.
Another object ot the invention is to provide
a calculating machine accumulator having elec
tronic devices as accumulating land storage
'. Another object of the invention-is to provide v 60
or vice-versa.
Another object of the invention is to provide
an electronic numerical accumulator wherein
stored data is represented by the relative elec
tronic ,state of its parts, with an electro-me
chanical means for sensing the stored data
>without disturbing the electronic conditiouoi
Another- object of the invention is to provide
prises a plurality of sets of electron tubes, one
for each denomination of the accumulator, each
set including an electron tube for each digit of
means for visually indicating the data in a nu
merical accumulator having the data stored
therein in electronic devices.
Another object of the invention is to provide
means to set an electronic type of numerical ac
cumulator to represent zero.
the denomination. The tubes of each set are con
nected in an endless operative chain so as to
be rendered conductive or caused to operate one
at a time in sequence, in response to sequences
of electric potential impulses impressed on the
Another object of the invention is to provide
corresponding denominational input conductor
means to set a visible indicator to "indicate the
numerical condition of an electronic type of ac 10 with' which the‘set of tubes is coupled. The
amount registered on the accumulator may be
Another object of the invention is to provide
noted by observing which tubes of the sets are
means to set an electronic type of numerical ac
cumulator in accordance with the data set up on
Means are provided -by which the completion
a visiual indicator, said entry being made without 15 of a sequential chain of operations of a set of
physical movement of any parts.
tubes in the accumulator will produce automatic
With these and incidental objects in view, the
ally anv electric potential impulse in the input
invention includes certain novel features of con
conductor associated with the next higher de
struction and combinations of parts, the essen
nominational set of tubes, whereby to effect a
tial elements o1" which are set forth in appended 20 carry-over from one denomination to the next
claims and a preferred form or embodiment of
higher denomination.
which is hereinafter described with reference to
As indicated above, the accumulator is actu
the drawings which accompany and form a
ated by means of impulse sequences impressed
part of this speciñcation.
upon the denominational input conductors, with
Of said drawings:
25 which the sets of tubes are coupled. The accu
Fig. l is a diagrammatic chart explanatory of
mulator is actuated differentially by means of
the functional relation between theJ several units
an impulse generator, the output conductors of
of the machine.
which are connected to the respective input con
Fig. 2 is an elevation of a typical key bank,
ductors of the accumulator.
Said impulse gen
partly broken away.
30 erator consists of a plurality of banks of electron
Fig. 3 is a cross section through the key bank
tubes, one bank for each denomination, and each
of Fig. 2 on the line 3_3.
Fig. 4 is a side elevation of the step-by-step
operating magnet for one denomination of the
indicator, the accumulator sensing means driven «.
thereby, and the indicator set in accordance
bank including an electron tube for each of the
digits “l” to “9” inclusive. Each bank of electron
tubes is so interconnected that, when operation
of 'the' ñrst tube of the bank is initiated, the
remaining tubes in the bank may be caused to
operate automatically in sequence, and, as each
tube in the bank operates, `or becomes conductive,
it generates an electric potential impulse which
is transmitted to its output conductor and, hence,
Fig. 5 is a section through part of the com
mutator and Wiper arm assembly of the accumu
lator sensing means shown in Fig. 4.
Fig. 6 is a wiring diagram of two sets of elec
tronic devices, constituting two denominational
orders, and exercising diiîerential control over
the accumulator.
Fig. '7 is a wiring diagram of an enlarged sec
tion of a portion of the units denomination set of
electronic device shown in Fig. 6.
Fig. 8 is a wiring diagram of the main switch
and the manually-operated control circuits for
non-indicating, resetting, and restoring opera
Figs. 9A, 9B, and 9C, taken together, form a
Wiring diagram of the units denomination of the
Figs. 10A, 10B, and 10C, taken together, form
a wiring diagram of the tens denomination. of
the accumulator.
Fig. ll is a fragment of a Wiring diagram, simi
lar to Fig. 6, showing the connections for caus
ing entry of data into the accumulator starting
with the highest denominational order.
General description
The machine embodying the invention may be
conveniently considered by sections which are
functionally comparable to the key banks, differ
ential actuator, accumulator and visual indicator
of a purely mechanical calculating machine. The
relation of these sections, as regards their func
tion, is shown diagrammatically in Fig. l.
The calculating apparatus of our invention,
to the corresponding input conductor of the accu
mulator. A series of switches are provided for
each bank of tubes, which switches are selectively
operable to determine the number of tubes in the
bank that will operate sequentially and, thus,
determine the number of impulses in a sequence
to be generated by the bank and transmitted to
the corresponding denomination of the accumu
lator. These switches of the several banks are
selectively controlled so that, on each denomina
tional input conductor of the accumulator, there
will be impressed an impulse Sequence, having a
number or" impulses in the sequence correspond
ing to the digit, in the corresponding denomina
tion, of the item to be entered. These switches
may be selectively controlled by means of banks
of digit keys, upon which the operator sets up
the items to be entered.
The apparatus illustrated herein also includes
an electro-mechanical sensing and indicating
means for rendering visible and readable the data
accumulated, which means acts to set the dials
automatically with respect to the conductive con
dition of the tubes in the accumulator banks. The
apparatus includes, also, means to reset the accu
mulator to zero; that is to say, means by which al1
tubes of the accumulator may be caused to cease
operation and the zero tubes then caused to oper
ate. The apparatus includes, also, means whereby
which attains the objects stated hereinbeíore,
includes an accumulator for registering the items
entered and for preserving the sum of such items,
the sensing and indicating means may be utilized
automatically to set the accumulator in accord
ance with the amount standing on the indicator;
that is to say, to cause those tubes of the accu
mulator to operate which correspond to the read
and such accumulator, broadly considered, com
ing of the indicator.
The apparatus includes,
materials by perforatlons, light-controlling areas,
also, various control devices by which the opera
tion of the apparatus is eiîectively controlled.
The disclosed machine has a keyboard of two
denominations of nine keys each, representing
the units and the tens denominational orders of 5
the decimal system of numbers. These key banks
electrically-conductive areas, or magnetized
The key bank control is used in this
embodiment as one example of selective circuit
switching means.
The electro-mechanical sensing and indicat
ing means is constantly ready to indicate new
may have set thereon any number from 1 to 99
for entry into the machine in one operation.
totals as new data is entered and is relatively slow
in operating compared with the time taken to
The section corresponding in function to a differ
ential actuator comprises units and tens denomi 10 make an entry of data into the accumulator, yet
national orders corresponding to the keyboard,
it will follow the operation of the accumulator
and ultimately indicate the amount ñnally stored
each of which denominational orders acts under
control of its associated key bank to enter data
in the accumulator, as it is not positively connect
ed to the accumulator, but merely explores its
into the accumulator, and is purely electrical,
having no moving parts except for the key release 15 electrical condition until the amount finally
and the “single operation” control cooperating
stored in the accumulator is sensed, and then
therewith. This section is referred to hereinafter
stops. If the amount changes, the exploring com
mences again. The indicator is mechanically at
as the “differential actuator.” The accumulator
is purely an electrical device and has, in addition
tached to and shows the position of the exploring
means at any time.
to the units and tens denominational orders
represented on the keyboard, a hundreds or over
The diiïerential actuator (Figs. l and 6) is
ñow denomination. The accumulator includes a
purely electric means associated with each de
nominational order of the accumulator for
transferring carry-overs from one denomination
composed of a group of nine grid-controlled
gaseous electron discharge tubes for each de
nominational order. The tubes in each denomi
national order consist of a “starting” tube and
to the next higher denomination. The visual
indicator may be set by an electro-mechanical
sensing means for each denomination, which
means sense, and are controlled by, the data
representing electrical condition of the associated
denominational order of the accumulator. The
principle embodied in the disclosure can be ex
the nine tubes representing the nine digits 1, 2,
3, 4, 5, 6, 7, 8, and 9. These tubes are arranged
in a circuit whereby, commencing with the start
ing tube, they may be ñred and rendered electri
cally conductive one at a time in sequence, one
tube being ñred by the conditions occurring dur
ing the starting of conduction in the next lower
tube, which lower tube itself lis extinguished as
panded indeiinitelyv in respect to the number of
key bank controlled denominations and in respect
the next tube in the series is rendered conductive.
to the number of overflow denominations and 35 The starting tube in a denominational series
their associated indicator units. The drawings
is iired by closing the starting switch |00 (Figs.
disclose this sectional plan of construction of the
l and 6) to commence the automatic sequential
machine. The keys, certain controls dealing with
operation. The firing of the starting tube fires
special operations, the key release mechanism,
the “l” tube and the iiring of the “l” tube lires
and the sensing and the indicating devices are 40 the “2” tube. The firing of the “2” tube fires
the only mechanically moving elements in the
the “3” tube and extinguishes the “l” tube. This
machine. While the drawings show only two
process continues until the tube representing the
denominational orders in the keyboard and three
depressed key is reached, which tube, upon being
in the accumulator and in the indicator, as many
fired, cannot fire the tube having the next higher
additional denominational orders may be used as
digit value as the anode-energizing circuit of
the tube having the next higher digit value is
After the keys have been manually set and
broken by a switch operated by the depressed
a starting switch lili! (Figs. l, 6, and 7) has been
key. The ñring of each tube in a denominational
closed, the data is entered into the accumulator
series, except the starting tube, impresses an
with a speed limited only by ordinary electrical 50 electric potential impulse upon an output con
circuit characteristics, such as resistance, ca
ductor common to all the digit-representing tubes
pacity, inductance, and ionization time, and not
of the denomination. There is one output con
limited by the physical movement of any me
ductor for each denominational order of the
chanical part. Data may be entered into the ac
actuator, and each output conductor is connected
cumulator many times faster than it takes to
to the corresponding denominational order of
set up the data manually on a keyboard and
the accumulator, as indicated by reference num
to close the starting switch. An approximate
bers I 5l! and |53 (Figs. l and 6). The number
time may be computed for the entry of data into
of impulses impressed on each denominational
such an accumulator if the circuit character
output conductor in a given operation is equal
istics are known. In the circuit to be described, 60 to the value ofthe depressed key in that de
the circuit element values are given as typical.
ln the particular embodiment based on these
The denominational groups of the differential
values, the longest time required to enter data
actuator are themselves operated sequentially,
of two denominational digits, after closing the
the firing of the tubes of the group in the units
starting switch, is approximately .0022 second,
denominational order being completed before
being the time required to enter the number “99,”
the firing of the tubes in the group in the tens
which is longer than the time required to enter
denominational order commences, or vice versa,
the number “1o.”
if desired, as will be explained. Timing elements
It is within the purview of this invention to
have been provided in each group of tubes of the
use any of the 'well-known means for controlling
the entry of data, other than the manual key
board described herein; for instance, the switch- .
ing of the differential actuator circuits may be ‘
controlled by any of the well-known methods for
sensing data such as that represented on record
differential actuator, which elements are oper
able, when the lower denominations are operated
first in the sequegpe, to give a slight pause before
the sequential ñring of the next higher denomi
national group of tubes commences, to permit
-denominational carry-overs to be made to that
denomination 0f the accumulator without inter
ference with the entry of the diiïerential data.
The electric potential impulses, as they occur
in the respective output conductors from the dif
condition of the accumulator tubes through elec
trically-connected contacts, one by one, until a
contact representing a conductive tube is located,
whereupon the operation of the sensing means is
ferential, actuate their respective accumulator
made to cease and the number which that tube
represents is thereby made visible by a number
wheel set in accordance with the position of the
then stationary sensing means. The sensing
means has exploring or wiper arms representing
orders, each impulse being so timed as to be
reecived by the accumulator before the next im
pulse is produced.
The accumulator consists of the three denomi
national orders, units, tens, and hundreds. Each
denominational order of the accumulator consists
of ten grid-controlled gaseous electron discharge
tubes representing the digits (l, l, 2, 3, 4, 5, 6, 7,
8, and 9, which are arranged in a circuit so that
they are fired one at a time in endless chain se
quence, either by the impulses sent through the
output conductor of its associated differential ac
tuator, or by impulses produced by the transfer
device, with the exception of the overflow de
nomination, which is actuated only by the im
pulses from the transfer device of the next lower
denominational order. The carry-overs from
one denomiation to the other are made by having
an extra electric impulse introduced in the next
higher denominational order upon the entry of
the next impulse in the lower order after any
“9” digit representing tube has been fired in that
lower order, said impulse in the lower order also
having its regular function of firing the “O” or
zero tube in the lower order. inasmuch as the
denominational groups of tubes of the differential
actuator are ñred in sequence, the accumulator
orders are added into in the same sequence. In
the circuits as disclosed, the pause between opera
tions of the different groups of tubes of the ac
a denomination, which arms when the sensing
means is operative, move over the sensing con
tacts until a conductive tube is sensed in the par
ticular denomination. If the wiper arm is sta
tionary on the contact related to a conductive
tube and the tube is extinguished by the entry
of data into the accumulator, the exploring move
ment of the wiper arm will commence and con
tinue until the new contact representing the new
accumulation is found.
The accumulator is cleared or set to Zero by
extinguishing all the tubes and subsequently ñring
the zero tubes in each denomination.
The sens
ing means then resume their exploring operation
and stop at zero in each denomination because
tho-se tubes are now conductive.
If the main supply of electric current be
switched off by main switch 90 (Figs. 1 and 8),
deenergizing the accumulator and the sensing
means before resetting the accumulator to zero,
the indicator will still have set thereon the last
amount in the accumulator. The accumulator
eelctron tubes, being deprived of current will have
no tube conductive and therefore will have n0
data therein. Under these conditions, in the
event the main supply of current is again turned
tuator is provided for the purpose of allowing
on by closing switch 919, the accumulator is caused,
the denominational carry-over impulse, if any, to
by the flow of energy through certain wiper arms,
actuate the next denomination of the accumu~
set with those previously referred to, 'to render
lator before impulses from the differential actu
the proper tubes conductive in accord with the
ator actuate it. Such interference between 40 data on the indicator. This restoring of data into
carryover impulses and differential impulses may
the accumulator is accomplished automatically,
bev rendered impossible by entering the data into
as will be explained.
the higher denominational order before entering
A non-indicate key switch 423 (l-T'igs. 1 and 8)
has been provided so that, upon opening said
it into the next lower denominational order,
which is done by arranging for the highest order
switch, the accumulator may be operated without
of the differential actuator to be operated first.
the indicator functioning. If the switch 423 is
This may be accomplished by using the units keys
closed after data-entering operations, the indi
(Fig. 1) as tens keys (Fig. 1l), and using the tens
cator will be set in accordance with the accumu
keys as units keys and having output conductor
lated data.
|50 lead to the tens bank input terminal of the 50
The action of gridecontrclled gaseous discharge
accumulator and having the conductor |53 lead to
electron tubes such as those used in the differen
the units bank input terminal of the accumulator.
tial actuator and accumulator, is well known. An
The accumulator, after having data entered
electric potential of sufficient magnitude im
therein, has one tube in each denomination re
maining in a conductive state, said tube repre
senting the digit in that denomination, of the
sum> of the accumulated data. Subsequent en
tries of data into a denomination cause a continu
ation of the sequential chain firing of the tubes,
beginning with the tube having the next higher
digit value to the conductive tube. Thus, the
accumulator differs from the actuator in that one
tube, in each order, is maintained conductive be
tween data-entering operations. Each tube in
the differential actuator is fired by the preceding
envelopea iscathode
and by
ing grid element which is normally provided with
a negative bias potential with relation to the cath
ode so as to prevent the flow of electrons to the
anode. If the biasing grid potential is reduced to
a point where it is no longer in control of the
emission of electrons from the cathode, current
will fiow at once through the tube from the anode
to the cathode and in so doing will ionize the in
ert gas within the tube. rThe ionization of the
gas within the tube causes
increase in the
tube, whereas the tubes in the accumulator are
fiow of electrons from the cathode to the anode
fired -by the impulses from the differential ac
and renders the grid incapable of further block
ing the electric ñow. This flow, once started,
A sensing means is provided for each denomi
will continue even though the grid be restored
national order of the accumuator, the presence of 70 to its controlling bias potential, and will not
a “zero” tube in each denominational order of
cease until the cathode-anode current is inter
the accumulator making it possible to sense the
rupted by some other means. When the gas in
zero or cleared condition of a denomination in a
the tube is ionized and the electron flow has
positive manner. The normally operative sens
started, the tube is said to have been fired, dis
ing means of each denomination explores the
charged, or rendered conductive. This is also
called the operating condition of the tube and
whenever, in this specification and the claims,
time lapse between the pressing of the starting
button and the consequent firing of the tubes
reference is made to causing an electron tube to
operate, it is intended to mean the bringing of
such tube to the condition of maximum conduc
tivity. The conductive tube may be extinguished,
or rendered non-conductive, either by adjusting
the cathode capacity and resistance so that for
in the differential actuator and the accumulator
may be as short as .001 second for the entry of
a single digit. From this it will be apparent that
the speed of making an entry into the accumula
tor is extremely fast in comparison to the speed
with which the data may be set up either by
manual keys as shown in this embodiment or by
other more rapid data entry control means such
as mechanically-sensed, electrically-sensed, or
an instant, as the capacitors are charging, there
is no flow of current from the anode, or by shut
ting off the potential completely. Under these
conditions the grid, if at controlling bias poten
tial, resumes control. Both of these phenomena
light-sensed records, which data entry control
means have been mentioned as within the pur
are used in the disclosed machine, as will be ex
view of the disclosure.
plained. Ordinarily the bias potential of the grid
The diagrammatic representation shown in
Fig. 1 illustrates the denominational groups in
with relation to the cathode is not kept at a hair
trigger point, but at a substantial biasl thus ren
dering the tube more stable and unresponsive to
the differential actuator, the accumulator, and
the indicator. These groups may be added to as
desired. There may be more than one overflow
slight fluctuations of potential of the grid.
The automatic sequential firing of the tubes in
the diiferential actuator is accomplished by plac
ing a high resistance in the cathode supply cir
denomination if desired,` but there must be one
accumulator order for each denomination of the
differential actuator and one indicator for each
denomination of the accumulator.
cuit of each tube, which causes an abrupt posi
tive rise in potential of the cathode of a tube as .
The principle of the invention, as set forth in
it ñres, and this abrupt rise in potential is uti 25 this disclosure, is embodied in a machine hav
ing certain electric supply potentials and elec
tronic devices of certain electrical characteristics.
In balancing the circuits, resistors and capacitors
lized through interconnecting circuits to extin
guish the tube of next lower digit value in the
series by temporarily raising its cathode poten
having a ñxed relationship with one another are
tial above the potential of the anode, and, by the
same positive potential rise, to destroy the grid 30 used. Electronic devices or potentials of differ
control of the tube having the next higher digit
Value, causing it to ñre unless it be cut out by
switch means operated by a digit-representing
In the accumulator, the same phenomenon
the 'rise in potential of the cathode when the tube
fires, caused by placing a high resistance in the
cathode supply-_is used to extinguish the tube
having the next lower digit value in the series,
ent characteristics may be used without depart
ing from the principle of this invention, merely
by using different values of resistance and capaci
ty to obtain the relationship disclosed herein.
The keyboard
The keyboard consists of a units denomina
tion key bank 6l (Fig. l) having nine digit keys
62 (Figs. 1, 2, 3, and 6) and a tens denomination
as is the case with the differential actuator, and 40 key bank 63 having nine digit keys 86 (Figs. 1
and 6). The keys in each bank are of similar
to weaken the grid control of the tube having
construction and a description of the keys in
the next higher digit value by reducing its bias
one bank will be suflicient for an understanding
to the trigger point so that the next potential
of all the keys.
impulse from the differential actuator, which im
pulses are common to all the tubes of the accu
mulator series,
weakened grid
planation will
accumulator is
will cause only the tube with the
bias to fire. More detailed ex
be given on this subject as the
describe more particularly.
The digit keys, by operating switches, control
the stopping of the firing of the tubes in each
of the differential groups after predetermined
numbers of tubes have been iired. As each tube
is ñred it produces, by the rise in its cathode
Each key has a stem 66 (Figs. 2 and 3) slida
bly mounted in alined holes in a top plate 64 and
a bottomplate 65 of a unitary key frame, said
plates being spaced and fastened together by
transverse vertical webs 13 and 14 (Fig. 2) each
50 of which has laterally projecting ears 61 to en
gage side plate members 68 and 69 (see also Fig. 3)
of the key frame. Each keyis provided with
a restoring spring 10 (Fig. 2) which engages vthe
bottom plate 65 and is contained in-a slot 1I in
potential, an electric impulse in a conductor com 55 the key stem where it is retained by projections
mon to al1 the differential actuator tubes in the
12. As a key is depressed, the spring compresses
denomination, which impulse isconveyed to the
against the bottom plate 65, giving the key an
` corresponding order of the accumulator, which
upward restoring urge. The keys are limited
causes the firing of the tube next in numerical
in their upward motion by a shoulder on the key
order. Thus, except for the release of the keys 60 stem 66 striking the top plate 611., A key lock
after the entry of the data and except for the
ing plate 15 (Figs. 2 and 3), having clearance
means to prevent a repeat entry while the keys
holes 16 for each key stem, is slidably mounted
are still depressed, there are no movements of
in clearance holes in the webs 13 and 14. The
mass involved in data-entering operations except
locking plate 15 is urged to the left, as shown
the‘mass of electrons and ions causing the elec 65 in Fig. 2, by spring 11 until the edges of the key
tric current. The only factors which limit the
clearance slots contact the key stems. As a
speed of the entry of data are electrical in na
key is depressed, the locking plate is forced to
ture and are placed in the circuit fory the proper
the right by a camming surface on the key stem,
timing of the impulses and ñring of the electronicuntil notch 18 allows the locking plate to move
70 to the left, locking the key in depressed position.
The speed of the actual entry of data into the
By chamfering each of the notch edges, the ac
accumulator is so extremely rapid that the time
tion of the key bank is made flexible, causing
of making such an entry is negligible in com
any depressed keys in the bank to be lrestored
parison with the duration of the manual move
when another key in the bank is depressed. Each
ments _necessary to press the starting key. The 75 key stem has inserted therein an insulating web
formed of two pieces 19 and 90 (Fig. 3) having
ears projecting into slots in the key stems 66
and into guiding slots 9| in the side plate mem
bers 68 and 69, so that the insulating web pieces
slide up and down with the keys. On each web
are four contacts 82, 83, 84, and 85 (Figs. 2 and
3) , each of which contacts in the up position can
close a circuit between one pair of switch points
and in the down position can close a circuit
between another pair of switch points. These
switch points are supported by the side plate
members 68 and 69. Therefore, by the depres
sion of a key, four circuits may be broken and
four circuits may be closed. The invention uses
but three of these four available pairs of switch
tion of this potential when the starting switch
is closed, a capacitor 26| of .l inicrofarad is con
nected from a point between the resistor |48 and
the solenoid |49 to the 150-volt negative line 95.
When no digit key has been depressed, the
closing of switch |60 after switch 90 has been
closed, in addition to supplying the plate poten
tial to tube |55, also supplies a. positive potential
to its grid 267 through switch |46, resistor |9| oi
200 ohms, resistor |62 of 100,000 ohms, through
the contact arms as |03, |94, closed on their upper
contacts since no keys are depressed, through the
conductor |52, common to both denominations,
switching may be accomplished by a single key.
A key release solenoid 26| for the units bank of
keys (Figs. 2 and 6), when energized, moves
and resistor 268. This V10-volt positive impulse
on the grid 261 changes the potential of the grid
from negative to positive and causes the tube
|55 to ñre and become conductive, the current
flowing through the plate circuit of the tube en
ergizing solenoid |49, which operates and closes
20 the circuit to key release solenoids 26| and 262,
lever` 263 counter-clockwise, around pin 264, to
as explained above, without any result as far as
points, the description of this key bank being
given to illustrate one way in which multiple
move the locking plate 'l5 to the right and release
the digit keys arev concerned, as none were de
a depressed key. A similar solenoid 262 causes
the release of any depressed key in the tens
However, if keys have been depressed-for ex
bank of keys. There is one gas-nlled electron
a1np1e,'the “5” key in the units bank and the “70”
tube |55 (Fig. 6), similar to those already de~
key in the tens bank-the 170-volt impulse intro
scribed, for controlling the operation of both sole
duced on conductor |52, by closing starting switch
noids 26| and 252. The control tube |55, when
§00 after the main switch 90 has been closed
fired, energizes a solenoid |49 to close the nor'
does not directly affect the grid 26?, but is
mally open switch |41, which supplies the ground 30 switched so that the 170 volts positive impulse is
ed solenoids 26| and 262 with 45 volts positive
impressed on the grid of the starting tube |69 of
potential, causing these solenoids to become ener
the units denomination, through line |60 and
gized and operate their armatures and thus re
resistor ||5 of 400,000 ohms, iiring that tube, as
lease any depressed digit keys.
The circuits entering into the operation of
the control tube |55 will now be considered.
As the main switch 90 (Figs. 1 and 8) is closed,
terminals'9l, 92, 93, and 94 are impressed, re
spectively, with the following electrical poten
will be explained, to start the sequential ñring
oi the tubes in the units bank. Tube |09 remains
conductive until its plate circuit is interrupted
by opening- switch |00 or switch |46 and as long
as this tube remains conductive it is impossible
to start the sending of a second group of impulses
tials: 170 volts positive, 45 volts positive, 6.3 volts 40 over output conductor |50. After the ensuing
positive, and 150 volts negative.
sequential firing of the “1,” “2,” “3,” “4,” and
Terminal 93, which has a potential of 6.3
“5” tubes of the units bank, and the starting
volts positive at this time, supplies the current
the n10,” U20,” n30,” “40,1: n50’n “60u
to heat the cathode 265 of control tube‘ |55 and
and “70” tubes of the tens bank, a positive cathode
is shown grounded in Figs. 6 and .7 through a
potential impulse caused by ñring the “70” tube is
typical heater filament symbolical of the heater
switched onto the common conductor |52 by the
ñlaments of all the tubes. The heater circuits
key-operated switch |6| (closed by depression of
from the terminal 93 to the tubes have been
a key in the bank of highest order) to fire the
omitted because they would tend to obscure othcontrol tube |55, the firing of which tube causes
er circuits in these figures.
60 the energization of the solenoid |49 and thereby
When the main switch 90 is closed and termi
the energization of solenoids 25| and 262 to cause
nal 94 has a 150-Volt negative potential applied
the release of the keys. The starting switch |00
thereto, the conductor 95 assumes this potential.
must be held closed until solenoid |49 is ener
Grid 26'! of the control tube |55, when no digit
gized, but this interval is so short that it is prac
keys have been depressed, assumes a normal bias 55 tically impossible for the operator to withdraw
of 150 volts negative by being' connected to the
pressure from switch |99 before solenoid |49 is
150-volt negative conductor through resistor 269
energized. When the solenoid |49 is energized,
_ of 250,000 ohms and the paralleled resistor and
switch |46 is opened to disconnect the common
capacitor comprising resistor |58 of 100,000 ohms
'conductor |52 and conductor |44, which supplies
and capacitor 620 of .005 rnicrofarad.
Gl) plate potential to the tubes of the differential
The cathode 265 of the control tube |55 is con
actuator, from the source of potential to which
nected to ground. With the grid 261 at a poten
they have been connected by the closing of the
tial of 150 volts negative and the cathode 265
starting switch |00. By thus removing the po
grounded, the tube |55 will not ñre.
tential from the plates of the tubes, any con
When the main switch 90 is closed, the l'IO-volt
ductive tube will be extinguished and none of
positive potential of terminal 9| will not be ap
the tubes can be rendered conductive thereafter
plied directly to the plate 266 of the control tube
until switch |46 is again closed and by switch |99
|55. However, when the starting switch |00 is
being again opened and closed, so that any im
closed the plate 266 has 170 volts applied thereto
pulses which would be generated by shifting con
through a circuit which extends from the ter 70 tacts as |04, |43, |5I, |6|, and |9| when the keys
minal 9|, over 'closed contacts of the starting
are restored to undepressed position with the
switch |00, through resistor |48 of 300 ohms and
starting switch |00 closed, would not cause a
the solenoid |49. To slow down the application
misoperation of the tubes.
of this potential to the plate and prevent the
When the “70” key is depressed, as described
possible firing of the tube by the sudden applica
above and shown in Fig. 6, switch |6| connects
the point 212; that is, the grid of control tube |55,
and by the speed of operation needed. It should
be evident from the explanation which follows
and common conductor |52 to ground through
the resistor 259 of 100,000 ohms, the resistor 210
that certain of the time factors involved result
of 25,000 ohms in parallel with a capacitor 213
from the proper choice of these values. With
the values given here as an example, the impulses
of .02 microfarad, through the tens denomina
tion output conductor |53 and the resistor 21| of
for the number “99” may be impressed on the
5,000 ohms. This causes the potential of the
output conductors |50 and |53 to the accumu
point 212 and grid 201, which are connected to
lator, as has been said, in about .0022 of a second
the 15G-volt negative conductor 05 through the
after the starting switch |00 (Figs. l and 6) is
resistor |58 of 100,000 ohms and capacitor 620 of 10 closed, and the number “l” may be impressed on
.005 microfarad in parallel, to drop from 150
the output conductor |50 to the accumulator in
volts negative to approximately 84 volts negative,
about .0003 of a second. If there were ñve
which drop is not sufficient to cause the tube to
denominational key banks, the number “99999”
fire or be conductive. If the circuit just traced
could be impressed upon the ñve output- con
were the only circuit in the tens bank, the point
ductors to the accumulator in about .0058 of a
212 would assume the potential of about 84 volts
second. Inasmuch as it is necessary for the
negative, but circuits associated with the “10,”
accumulator to respond to the impulses from a
given denomination of the differential actuator
U20,” “30,” H40,” “50,” M60,” and H809» tubes are
also included in the tens bank. These circuits
one by one, it is app-arent that its speed of re
form parallel paths which extend from the 150
sponse is somewhat higher than that of the
volts negative conductor 95 through resistors
actuator. The extremely high-speed production
638, G13, 653, 653, 000, GSi, and 61|, through
of differential impulses and operation of an accu
mulator by the imp-ulses are due to the fact that
they are accomplished solely by the ñow of elec
tric current without movement of ponderable
switches similar to ESI, (closed on the upper con
tacts since the keys are elevated) through re
sistors similar to 260, through resistors and
capacitors in parallel similar to 210 and 213, to 25 mass.
the tens denominational output conductor |53
The wiring of the circuits of a two-denomina-v
and thence through resistor 21| to ground.
tion dilîerential actuator is shown in Fig. 6. An
These parallel paths between the 15G-volt nega
enlarged section of part of the circuit is shown in
tive conductor 95 and output conductor |53 cause
Fig. 7, to which reference is principally made in
30 the following explanation.
the eiîective resistance of this part of the circuit
to become smaller and raise the negative poten
In giving the explanation of operation of the
tial of the tens output conductor |53 and also
sequential iiring of the tubes in the differential
raise the negative potential oi the point 212
actuator, the ñrst portion of the units bank
slightly above the 84 volts negative mentioned
(Fig. 7) is used as an example. This portion
above. This negative increase in potential of
shows starting switch |00, the “l” and ‘f2” digit
point 212 will not affect the operation of the tube
keys 62, the tubes |2| and |28 representing digits
|55. When the “'10” tube ñres, its cathode will
“l” and “2” respectively, the units denomina
acquire a positive potential which, through re
tional order starting tube |09 for starting differ
sistor 259, will cause the potential of the common
ential operation of the digit tubes when a key is
conductor |52, and point 212, to change so that
depressed in this order, the key release control
the potential of the grid 251 will become about
circuits, the circuit breaker switch >for “single
21/2 volts positive and this will cause the tube |55
operation” control, and the various circuits
to fire and become conductive. The manner in
coordinating these elements.
which the potential of the cathode of the “70”
The conditions resulting from the firing of the
tube is raised to a positive value to change the
starting tube |09 are such that they have no ef
potential of the grid 261 from negative to posi
fect on the digit-representing tubes except to
tive will be made clear during the description of
fire tube |2| representing the digit “1.” The
the operation of the differential actuator. The
method of ñring the “1” tube by a starting tube
ñring of tube |55 will result also if a key in the
to commence the differential action is used as a
units denomination bank is depressed and no key
convenient way of impressing a uniform ñring
in the tens denomination bank is depressed, as
impulse on the grid of the “1” digit-represent
the last tube to ñre in the units bank will have
ing tube |2|, in operations wherein a key of that i
its cathode positive potential impulse shunted
denomination is depressed. It is to be noted that
around the tens bank on conductor |52 to the
the starting tube could be replaced by any other
grid 251 of the key release control tube |55 in
means that would í'lre the “l” digit-representing
stead of to the starting tube |511» of the tens bank,
tube. The sequential firing of the tubes is so
by reason of all the key switches in the tens bank
rapid that the ñring of the “l” digit-represent
being in normal position.
Diyfîerential actuator
In describing the diiïerential actuator, as
regards its electrical operation, it is necessary to
trace the flow of electric energy through the
circuits. As the operation of the differential
actuator is dependent on relative values of the
ing tube vcannot be done reliably by the switch
|00 alone because of the possibility that the
operator might vibrate switch |00 in closing it,
thus giving more than one ñring impulse to the
digit-representing tube |21 before the keys are
released and causing the firing of the selected
tubes more than once, which would result in an
error in the entry of data. The starting tub-e is
not extinguished and therefore cannot be ñred
again until the data-entering operation is com
electron tube constants, for the timing and the
pleted and all the tubes are deprived of energy
sequence necessary in producing the differential
action, actual values will be given as an example. 70 by the opening of switch |45. It will be explained
later how the digit tubes are extinguished after
These values are given to show how the difieren
firing either by the action of the next tube firing
tial operates and should not be considered the
or by the completion of the data-entering opera
only set of values which can be used. The values
tion causing switch |46 to open.
used are determined by the input voltages
selected, by the type of electron tube selected, 76 Each of the digit-representing tubes |2| and
electric potentials, resistors, capacitors, and the
|28 has associated therewith a circuit which con
nects the 14o-volt negative conductor 95 to the
ground. The circuit for the “1” digit-represent
ing tube is representative and is traced as follows
starting tube |00 and the point in., which are
connected to ground through resistor ||6
from ground, through resistor |26 of 5,000 ohms
to point |24 `and output conductor |50, through
resistor |25 of 25,000 ohms and capacitor |35 of
.02 microfarad in parallel to point |23, through
resistor |30 of 100,000 ohms, through switch |64
of the unoperated digit key to point |20 and
through resistor |3| of 100,000 ohms, to the 150
ing, being connected through capacitor ||'|, of
.00005 microfarad, to point H0, through resistor
volt negative conductor 95. The cathode for the
"1” digit-representing tube |2| is connected in
of 25,000 ohms, will assume a slight nega
tive potential while the capacitor lll is charg
|45, of 400,000 ohms to point |00, which is lo
cated between resistors |ll| of 75,000 ohms, and
|42, of 100,000 ohms, connecting the 15G-volt
negative conductor 05 with ground.- When the
capacitor ||`| has become charged and current
no longer» iiows in this circuit, the point | |4 will
be at ground potential. The slight negative po
this circuit at point |23, and the grid for the
tential rise of the cathode |08 will not cause the
“2” digit~representing tube |28 is connected, 15 tube- |09 to be fired, because the grid |07 at this
through resistor |51 of 500,000 ohms, to the point
time has a potential of 150 volts negative and
|29. The connection of the cathode of the tube
of lower digit value to the grid of the tube of the
next higher digit value by means of circuits such
the characteristics of the tube are such that it
will ñre and conduct current :from the anode to
the cathode only when the potential of the grid
as this one enables the ñring of one tube to cause 20 exceeds, in a positive sense, a potential value of
the next tube to ñre in sequence.
Although but two digit-representing tubes are
here considered, the explanation given will serve
for the whole denominational bank of nine tubes,
positive terminal 9| is connected to the point |06
as the resistors, capacitors, and bias potentials
in the circuit from the 15G-volt negative con
used are of the same values. The firing of the
tubes occurs in so short a period of time, ranging
in the ten-thousandths of a second, that the
terminal 9|, through starting switch |00, through
15 volts more negative than that of the cathode.
Upon closing the starting switch |00 after the
main switch 90 has been operated, the l70-volt
ductor to the grid |01, which connection is from
the normally closed switch |40, resistor |0| of
transient changes in voltage cannot be measured
200 ohms, resistor |02 of 100,000 ohms, switch
with absolute certainty, and therefore, although 30 |03 in its normal unoperated position, conduc
the use of the resistors, capacitors, and the poten
tor |52, switch |04 in its operated position, and
tials of the electric supply lines of the values as
conductor |00 to the point |00, to which the grid
given will result in accurate operation of the
|01 is connected. This application of 170 volts
machine, the potential fluctuations in the cir
positive potential to the point |06 will cause the
cuits as stated should be deemed approximations
potential of the grid |01 to change from 150
and are `given chieiiy to explain the theory of
volts negative to about 9 volts positive with re
spect to the grounded cathode and will cause the
In the explanation of the operation of the
starting tube |09 to nre and be conductive. The
differential actuator as made in connection with
capacitor ||| of .005 microfarad in the circuit
Fig. '7, it will be assumed that the “2” digit key 40 connecting grid |07 with the 15G-volt negative
02 has been depressed manually-from a position
conductor 95 acts to slow down the application of
shown by the full lines to the position shown by
the ñring voltage to the grid l0?.
the dotted lines and the switches |04, |43, and
When the starting switch |09 was closed, as
|5| have been moved from the full-_line position
noted above, it also connected the plate ||0 of
to the dotted-line position.
f the starting tube |00 to the 170-volt positive
As mentioned previously, when the main switch
terminal through the circuit over the closed
90 (Figs. l and 8) is closed, terminals 9|, 92, 93,
switch |00, over the normally closed switch |46,
and 94 are impressed with the following electric
and resistor |0|, and from this point over con
potentials, respectively: 170 volts positive, 45 volts
ductor |44, capacitor ||2 of .005 microfarad in
positive, 6.3 volts positive, and 150 volts negative. parallel with resistor i i3 of 400,000 ohms, to
These terminals, also shown in Figs. 6 and 7, sup
plate | l0.
ply the necessary electric energy to operate the
As the starting tube rires, it allows electrons
differential actuator.
to flow. from the cathode |08 to the plate H0.
Terminal 93 of 6.3 volts positive, as has been
The ñow of current through the tube |09 is not
mentioned, supplies the current to heat the cath
limited by the 400,000-ohm high resistance ||3
odes of all the electron tubes in the differential
until capacitor || 2 becomes charged, at which
actuator and accumulator and is shown grounded
time the resistor ||3 becomes effective to reduce
in Figs. 6 and 7 through a typical heater filament
the plate-cathode current and also to reduce the
symbolical of the filaments of all the tubes. 'I'he
potential of cathode |00. The potential drop
heater circuits from the terminal to the various
across the tube |09, when conductive, is about
tubes have been omitted for the reason that they
15 volts as is usual in gaseous electron tubes of
would tend to obscure the other circuits to be de
this type. This makes point ||4 have, after the
scribed. Heater elements, which have been
ñring of tube |09 and as capacitor ||2 starts to
symbolically shown in each tube, are connected
charge, a potential of about 155 Volts positive
to terminal 93 and become heated when the main
with respect to ground. When resistor ||3 as
switch 90 is operated.
When the main switch 90 is closed andthe po
tential of 150 volts negative is applied to con
ductor 95, the grid of the starting tube |09,
sumes the current load as the capacitor |I2 be
comes charged, the potential of the plate ||0
drops to about 25 volts positive with respect to
ground, and the cathode |08 and point ||4 as
which is connected to this conductor through re
sume a potential of about l0 Volts positive with
sistor |05 of 100,000 ohms and capacitor | || of
respect to ground. After the ñrst surge of cur
.005 microfarad in parallel,.point |05, and re
rent from plate ||0 to cathode |08 in tube |09,
sistor | I5 of 400,000 ohms will assume a negative
the resistor ||3 makes the current i'iow very
potential ol’ approximately 150 volts. At the
small. Resistor ||6 limits the cathode current
same time, the potential of thecathode |08 of the 75 flow Abefore resistance ||3 takes effect and acts
to make the potential of cathode |08 high while
capacitor H2 is charging. Resistors |05, of
100,000 ohms, resistors |0| and |02 totaling
100.200 ohms, and resistor H5, of 400,000 ohms,
so that cathode | 20 and point |23 will have a po
tential slightly less than 155 volts positive with
reference to ground. It should be noted that the
resistor |0| of 200'ohms in the plate circuit is
limit the grid current. It is seen, therefore, that,
much smaller than the resistors |25 and |20
as tube |09 fires, a momentary voltage surge of
totaling 30,000 ohms in the cathode circuit and
approximately 146 Volts positive is impressed
the voltage drop across the resistor |0| will have
across the .00005 microfarad capacitor H1 to
but little eiîect in changing the potential of plate
point H8 and causes a positive Voltage impulse~
i 22 when the tube hres.
of about 145 Volts to be to be impressed at said 10
At the moment the tube fires, the current in
point H8. Point H8 is normally at a potential
the cathode circuit between points |23 and |20
of 64 volts negative with respect to ground, be
momentarily will be principally through the ca
ing connected through resistor |05 of 400,000
pacitor |35 and very little will ñow through the
ohms to point |40 between resistor 10| of '15,000
resistor |25, so that there will be a very small
ohms and resistor |42 of 100,000 ohms connect 15 voltage drop across this resistor and points |23
ing the ground conductor with the 150-volt nega
and |24 will have about the same potential= |55
tive conductor 95.
volts positive with respect to ground. As the ca
The grid of the “1” digit-representing tube is
pacitor |35 becomes charged, more current will
connected, through resistor |56 of 100,000 ohms,
iiow through resistor |25 and the potential drop
to the point H8 and assumes its normal poten-` 20 across the resistor will cause the point |24 to
tial of 64 volts negative, which changes to a posi'
have a more negative potential than point |23..
tive potential of about 82 volts when the starting
The rise of the potential of the cathode |20 to~
tube fires and impresses the positive potential
ward 155 volts positive will cause the grid |32 of
surge of 146 volts on point H0. When the main
the “2” digit-representing tube | 28, which is con
switch 90 is closed and the 150 volts negative po~
nected to point |23 through resistor |30, unopertential is applied to conductor 95, current will
ated switch |50, point |29, and resistor |51, to
ilow in each of the circuits associated with the
change from its normal negative potential of 84
digit-representing tubes, such as the one traced
volts to a positive potential of approximately 2.5
earlier herein from the 15G-volt negative conduc
volts. This change in potential of grid |32 will
tor 95 through resistor |3 l, point |29, switch |00 30 not cause the “2” digit-representing tube to lire
in normal position, resistor |30, point |23, paral
immediately, because the point |24 and conducn
leled resistor |25 and capacitor |35, output con
tor |50 have about the same potential as point
ductor |50, point |24, and, through resistor |20,
|23 when the capacitor |05 begins to charge and
to ground. The potentials of the points |23 and
the cathode |21 of the “2” digit-representing
|29 will become fixed after capacitor |35 be 35 tube, which cathode is connected to output con
comes charged, and the only current flow will be
ductor |50 by the resistor |31 and capacitor |30
that determined by the resistors. Under these
in parallel, will have a potential change similar
conditions, the point | 23 and cathode |20 of the
to that of grid |32 and will retain the effective
“l” digit-representing tube connected thereto will
biasing potential difference between the grid |32
assume a potential of about 19 volts negative, 4:0 and cathode |21 of the “2” digit-representing
point |20 and the grid |32 of the “2” digit-repre
tube so as to prevent the tube from firing imme
senting tube connected thereto will assume a po
diately. As the capacitor |35 becomes charged
tential of 84 volts negative, and point | 24 and the
output conductor |50 connected thereto will as
and current begins to fiow in resistor |25, there
will be a potential drop across this resistor which.
sume a potential of 3.2 Volts negative.
45 will increase as the capacitor becomes charged
When the starting switch |00 is operated after
and more current iiows through. the resistor.
the main switch 90 is closed and the “2” digit key
Under- these conditions, the positive potential of
is depressed, the 170-volt potential is applied to
point |20 and the output conductor |50 will de
plate |22 of the “l” digit-representing tube
through a circuit traced from terminal 9|, oper
ated starting switch |00, switch |45, through re
sistor |0| of 200 ohms, conductor |40, andv
through operated switch |43.
With the grid | |9 of the “1” digit-representing
tube normally at the same potential, 64 volts
nega-tive, as is point H8, and the cathode |20 at
a potential oi 19 volts negative, the gaseous tri
ode “1” digit-representing tube | 2| is kept from
crease as the drop across the resistor |25 in
50 creases, while the potential of the point |23 re
mains unchanged, so that, while the potential of
the grid |32 remains at 2.5 volts positive, the po
, tential of the cathode |21 will drop below 17.5
volts positive, at which time the potential of grid
|32 will exceed, in a positive sense, a potential
value 15 volts more negative than that of the
cathode |21 and the “2” digit-representing tube
|28 will ,fire and be conductive.
Through the same circuit as described above
When the 14S-volt positive potential impulse, 60 in connection with the “l” digit-representing
caused by the ñring of the starting tube |09, is
tube, the plate of the “2” digit-representing tube
impressed upon the grid H0 of the “1” digit-rep
has impressed thereon a potential of about 170
resenting tube |2|, it is apparent that grid H0
`volts positive. The cathode circuit for the “2”
will become temporarily about 82 volts positive
, digit-representing tube is similar to the one for
with respect to ground, or 101 volts positive with
the “1” digit-representing tube, so that, as the
respect to the 19-volt negative cathode |20, and
“2” digit-representing tube |20 fires, its cathode
the tube |2| will lire. The voltage impulse at
|21 rises to a positive potential or" about l5
point H8 which ñres tube I2! is kept from
volts and the' potential of output conductor |50
grounding by resistor |45 of 400,000 ohms. Re
also rises toward 155 volts. Just as in the case
sistor |56 of 100,000 ohms in series with resistor
of the “1” digit-representing tube, this potential
|45 limits the grid current of grid H9.
drops oiiî` after capacitor |30 becomes charged
When the tube |2| ñres and the gas therein
and current flows through resistor |31.
becomes ionized, the internal resistance ofthe
Since the “1” digit-representing tube is con
tube dropsand the potential difference between
ducting when the “2” digit-representing tube
plate-l 22 and cathode |20 drops to about 15 volts, «' iires, its cathode |20 is at 155 volts and the surge
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