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Патент USA US2601496

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June 24, 1952
2,601,492
G. T. BAKER
MEASURING ARRANGEMENTS
original Filed Jan. 7, 1949
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June 24, 1952
Q_ T, BAKER
2,601,492
MEASURING ARRANGEMENTS
Original Filled Jan. 7, 1949
2 SHEETS--SHEET 2
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Patented June 24, 1952
2,601,492
UNITED STATES PATENT OFFICE
2,601,492
MEASURING ARRANGEMENTS
George .Thomas Baker, Liverpool, England, as
.signor to Automatic Telephone & Electric Com
pany Limited, Liverpool, England, a British
company
@riginal application January 7, „19519, Serial No.
69,690. Divided and this application .June 19,
1950, Serial No. 168,995. lIn Great Britain
January 30, ,194.8
9 lClaims.
1
The present Vinvention relates to circuit ar
rangements employed for indicating the ,value 0f
electrical Componentssuch as condensers and re
sistances.
It is _known to measure .a Short .time .interval
by employing .a ¿resistance/,Condenser .combina
tion arranged so that `the condenser discharges
through the resistance. The time interval is
given by
where En is the voltage .across the condenser at
the discharge time 'has a value between the two
comparison time intervals.
:In one «embodimentof :the invention for deter
mining »whether the value vof the component lies
between -two limiting values, a .gate circuit is
opened land closed at y.times vduring the discharge
period of the condenser which correspond to the
limiting values. nOnly if the component under
test »has .a value »between the limiting values will
kan impulse pass `through the gate to control an
indicator vsuch as, for instance, a discharge tube.
In a further embodiment of the invention for
»the same purpose, the discharge time interval is
vcompared with ytwo known time intervals by the
age facross the .condenser _at ztheend >of y.the >inter 15 use >of three «relaxationïcircuits Two of the .cir
cuits include lcomponents of yknown value while
val. From this `eguatioriit=wi1l .be seen that .if
the third 'fincludesthe »component under test. By
suitably Yconnecting >the outputs of `the relaxation
circuits yto an indicator comprising aplurality of
and either .C or .R is ñxed, >the .equation ¿becomes 20 discharge tubes, `the tubes ‘can-be arranged to ín
,dicate not only whether 4the `component value is
C=Kit or R=K2t '
>Within the desired 'limits but also if it is not
whether the Value «is Vbelow or above said limits.
>thus the value of «the condenser or resistance is
YIt cfrequently'happens that lrepetitive measure
directly proportional ¿to .the time ¿taken for the
voltage across the. condenser in .a resistance/con 25 >ments -have to be ¿made cna component. Nor
mally _each measurement 4is »initiated by a key or
denser .combination to change from .one prede
‘like operation. >Such »repetitive key operation be
termined value `to another. Copending U. S.
comes tedious and it -is «a lfurther object of the
patent application .of .this applicant, Serial No.
invention to provide Vcircuit arrangements which
69,690, filed January 7, :1949, from `«which the
'
present application is divided, makes vuseof this ..310 avoid this necessity.
`According
»to
this
=feature
of
the
invention a
relationship `to give an indication vof the Vvalue of
pair of electromagnetic relays are `provided and
a condenser or a resistance.
yarranged »for automatic sequential operation, one
One of the objects of the present invention is
_of the relays serving xtoreset-the counting circuit
to provide aicircuit arrangement whereby an in
dication is `given as to `whether -the value of _a 35 while Ithe »other initiates a measuring cycle.
The xinvention «will be better understood from
component; lies .between 'two limiting `values.
the following description of a number of embodi
Another object of the present linvention is Vto
ments _taken in conjunction with the accompany
provide a circuit :arrangement `whereby in addi
Ving drawingsand-comprisinggFigs 1 to 4. In the
tion to giving an indication if the vvalue ofthe
drawings,
.component ffalls within the limiting -values, »an
Fig. '1 shows a-block schematic of an arrange
indication is A‘also given, if I'the :value is Aoutside
ment `lor indicating _whether lthe Value of a con
the limiting values, ~as Ato whether Vthe Ävalue is
denser or ìaresistance approximates within pre
above or below the limiting ivalues.
determined limits 4»to _a -nominal 'value while
According to a .featureot the invention, in a.
vcircuit arrangement -ïfor vindicating whether :the v.45 Ä'Fig. -2 shows the detailed circuit.
Fig. '3 shows van »alternate arrangement to that
value of ,a resistance lor acondenser is >between
the :beginning `.of ...the ,interval and E; is .the volt
two limiting vvalues :means are provided «for
charging and >discharging ¿thecondenser in a .re
sistance/condenser :combination »which includes
of Fig. l and »in laddition is .so arranged that if
ìthecornponent »value is outside the predetermined
limits, >an indication .isgiven whether the value
_the component :to -be tested and ithe-time ¿taken 50 is .above or zbelow such :limits while
Fig. A shows .the .detailed circuit.
¿for the 4.voltage,across ¿the .condenser itc change
„from one predetermined Vvalue @to .another prede
`Assume Ythata number. of condensers are manu
factured having a nominal capacitance ofgCn. If
termined/«value ¿is compared Vwith ftswo :time »inter
vals corresponding to ¿the twolimitingfvaluesiof
‘tghßßßllsliantglìf QL‘OPQITlQíQnëlÍÈY Of .1K1 rßfëïl‘ed t0
thecomponent,r anzindicationbeing given whether .55
2,601,492
3
pulse source is used, a capacitance of exactly Cn
will indicate 100 time units while the count on
any other component will indicate directly its re
lationship to the nominal value. For production
testing it is usually sufficient to indicate whether
the deviation exceeds a specified value. For in
stance, a common tolerance is 10% i. e. for a
nomina-1 value of 10 time units the unknown
capacitance must register more than 9 and less
than 11.
Referring now to the drawings it should be
explained that the references such as A2, G1 and
C shown in Figs. 1 and 3 correspond to the anode
of the valve V20, the grid of the valve V21 and the
signal input to the gate valve V21. In the arrange
ment shown in Fig. l six scale-of-two circuits are
interconnected to form a twelve point cyclic
counter S12. This is driven continuously from a
suitable pulse source and in the zero position, a
start pulse is applied to the test multivibrator l,
SSA comprising two back coupled valves V22 and
V23, the coupling between the anode of V22 and
the control grid of V23 being A. C. while that
between the anode of V23 and the control grid of
V22 is D. C. so that the stage has one stable and
one unstable condition of equilibrium. The stable
condition corresponds to the flow of current
through the Valve V23. The start impulse causes
the multivibrator SSA to be transposed and a
negative-going pulse is applied to the inner con
trol grid of the gate valve of the gate circuit G.
This negative-going pulse is, however, without
4
be non-conducting. The zero negative-going
pulse from the counter is applied to the grid of
V23 which transposes the condition of the multi
vibrator so that V22 conducts and a negative-going
pulse is developed across the anode load. This
is without effect on the inner grid of the gate
valve V24 since this grid is, yalready biased to cut
ofi. In the `toggle circuit S1, the normal condi
tion is with the valve V20 non-conducting and the
valve V21 conducting. The potential at the point
A2 is, therefore, low and hence the fourth grid
of the gate valve V24 is biased negatively with
respect to the cathode. The 9th pulse from the
cyclic counter is applied via C22 yto the grid of V21
whereby the condition of the circuit is transposed
and V21 now becomes non-conducting. The volt
age at the point A2, ltherefore, rises and the
potential of the fourth control grid of -the gate
valve V24 becomes positive with respect to the
cathode and the gate is opened. The 111th im
pulse from the counter is applied via C21 to the
control grid of V20 and causes the circuit S1 to
revert to its normal condition andthe potential
of the fourth grid now becomes negative with
respect to the cathode and the gate is closed.
The time taken for the test multivibrator SSA
to revert to its original condition will be deter
mined by the value of the condenser C26 under
test and if this reversion ta-kes place between the
9th and 11th pulse, indicating `that the value of
the condenser is within the specified limits, then
a positive-going pulse will be developed in the
anode circuit of V22 and will be applied to the
inner grid of the gate valve V24 at a time when
the gate is open. A negative-going pulse will be
developed in the `anode circuit of the gate valve
circuit S1 which is simply a circuit having two
and this will be fed via the condenser C25 to the
stable states of equilibrium. The circuit S1 con
control grid of the valve V22. The normal con
trols the opening and closing of the gate circuit
dition of the pulse lengthening circuit is for V22
and the arrangement is such that the gate is
opened on the 9th and closed on the 11th pulse. 40 to be conducting and V25 to be non-conducting so
that there is not sufficient potential across the
If now the test multivibrator SSA reverts to its
neon tube NT to cause it to flash. The pulse
normal condition while the gate circuit is opened,
obtained
from the anode of the valve V24 will be
that is to say, between the 9th and 11th pulses, a
eiîect since the gate va-lve is already cut-off on
the inner grid. The 9th and 11th pulses from
the counter S12 are applied to a so-called “toggle”
negative-going pulse will be developed in the
negative-going and will ‘transpose the pulse
anode circuit of the gate valve V22x and this will
be applied to a second multivibrator SSB which
is again similar to the test multivibrator and
which acts as a pulse-lengthener. The trans
position of the pulse-lengthener due to the nega
tive-going pulse causes the neon tube associated
lengthening circuit so :that V25 now conducts and
the voltage `at the point A1 will fall to such an
extent that the neon tube will ñash. It will be
thereby indicating that the condenser has a value
within the stated limits. It will be understood
that if the test multivibrator SSA reverts to its
normal condition before the 9th or after the 11th
It will be understood that the circuit will op
erate continuously so that if desired, a. number
of tests may be made on each component.
understood that the neon tube will only remain
lighted for the time taken for the pulse lengthen
ing circuit to revert to its normal condition and
duration is suitably selected so that the
with the pulse-lengthening circuit to flash 50 this
lighting of the neon tube is easily visible.
Once the high tension supply is connected to
pulse, no pulse will be developed in the anode 55 the circuit the only operation necessary to ef
circuit of the gate valve and the neon tube will
fect the test is to connect the condensers one
not flash.
by one to the terminals 2| and 22. Thus the
Referring now to the detailed circuit shown in
whole equipment may be controlled by a single
Fig. 2 the toggle circuit S1 consists of two cross
connected valves V2u and V21 each having an 60 switch for connecting up the H. T. supply and
a pair of terminals will be provided on the
anode load R20 and R25 and feed-back circuits
panel of the instrument to which the compo
from the anode of V20 via R21, C21 and R23 to the
nent under test is connected.
grid of V21 and from the anode of V21 via R26,
The circuit shown in Figs. 3 and 4 is a refine
C22 and R24 to the grid of V20, the resistances R21
ment of that shown in Figs. l «and 2 in that if
and [email protected] being connected ‘to the negative terminal
the value of the component is not within the
of the supply voltage via resistances R22 and R22.
specified limits, an indication is given as to
The values of the various resistances in the toggle
whether it is below or above such limits. Re
circuit are such that the circuit is negatively
ferring first to Fig. 3, the equipment comprises
polarised. The cyclic counter S12 is not shown in 70 three multivibrators SSN, SSo and~SS1= of which
detail since the circuit is well known and simi
larly the pulse source for driving the counter is
not shown.
In the normal condi-tion of the test multi
vibrator, valve V23 will be conducting and V22 will
the multivibrator SSO includes the component
under test. The other two multivibrators in
clude fixed condensers and provide two time pe
riods, a minimum TN and a maximum TP.
The
actual time To corresponding to the nominal
5
»2,601,492
value of the capacitor is limmaterial but is con
veniently taken to be about 0.4 second, :corre
sponding to a laf. condenser associated with a
100 k. ohms resistance. Part of the resistance
valves V37, V33 and V41 conducting. As regards
the toggle circuits the normal condition is with
the valves V31, V33 and V35 conducting.
A start pulse is applied to the three multivi
in the timing circuit of the .multivibrator SSN
brators in parallel by the operation of relay IBR.
is made variable and a similar variable is em
This start pulse will be positive-going and is
applied to the grids of the non-conducting valves
ployed in the timing circuit of the multivibrator
SSP. Over the range covered, time is linear
V36, V33 and V40. The three multivibrators are
with resistance so that the scales yof the vari
transposed substantially simultaneously and
ables can be calibrated directly in percentage 10 consequently positive-going pulses will be de
decrease or increase on To. The resistance asveloped at the points A2. These positive-going
sociated with the multivibrator SSO can be set
pulses will be applied to the toggle circuits SIA
so that the nominal capacitance vof the unknown
and SIB but as previously pointed out, they will
condenser corresponds to a release time of To.
be without effect as the toggle circuits are po
For a condenser within the speciiied limits, 15 larised to respond only to negative pulses. As
TN<TO<TP so that if the three multivibrators
suming first that the condenser under -test is
are set in operation simultaneously, they will
revert in the order SSN, SSo, SSP. The order
in which they actually revert is indicated Vby
three indicating or »toggle circuits SIA, SIB and
within the speciiied limits, then the multivibra
tor SSN will be the first to revert to normal.
When this takes place, the valve V37 becomes
conducting and a negative-going pulse is fed
SIc. In the normal condition of these circuits
the neon tubes NTA, NTB and NTC are extin
from the anode of V37 via condenser C30 to the
grid of valve V31 which it will be remembered
is conducting. This pulse, therefore, causes the
toggle circuit to be transposed so that the anode
voltage of V31 increases and that of V30 de
guished. If the multivibrator SSN reverts to its
normal condition before the multivibrator SSO,
a pulse is fed from SSN to SIA to cause ‘the neon
tube NTA to glow. Then when the multivibra
creases. The increase in anode voltage of V31
tor SSO reverts, the tube NTA is extinguished
is without eiiect on the toggle circuit SIB while
and a negative pulse is fed from SIA to SIB to
the decrease of anode voltage of V30 causes a
cause the neon tube NTB to glow. Finally when
potential difference to be developed across the
the multivibrator SSP reverts, the neon tube 30 neon tube NTA which thereupon glows.
NTB is extinguished and a negative pulse is fed
The circuit remains in this condition until the
to SIC to cause the neon tube NTC to glow.
multivibrator SSO reverts to normal when a neg
When the test has been completed, the neon
ative-going pulse from the anode of V33 is ap
tube NTC is extinguished and a second start
plied via the condenser C31 to the grid of V30.
signal is given by relay equipment similar to
This causes the toggle circuit SIA to revert to
that shown in Fig. 2.
its original condition whereby the neon tube
If however, the multivibrator SSO reverts be
NTA is extinguished and a negative-going pulse
fore the multivibrator SSN, the pulse applied to.
is fed from the anode of V31 via condenser C32
SIA by SSO will be without eiïect while that
to the grid of V33 of the toggle SIB. The toggle
subsequently applied by SSN will cause the neon 40 SIB. is thereby transposed and the neon tube
tube NTA to glow but neither the neon tube
NTB glows in a similar manner to that described
NTB nor NTC will glow since no pulse is passed
for the toggle circuit SIA. The circuit remains
on from SIA to SIB or SIB >to SIO. Further the
in this condition until the multivibrator SSP
reversion of SSP is without effect, so that the
reverts to normal when a negative-going pulse
tube NTA continues to glow. Again if the
from the anode of V41 is fed via condenser C33 to
multivibrators SSN and SSP the neon tube NTA
the grid of V32 thereby causing the neon tube
will glow when SSN reverts and will be extin
NTB to be extinguished and a negative-going
guished when SSO reverts and a pulse will >be
pulse to be fed from the anode of V33 via con
fed over SIA to SIB to cause the neon tube NTB
denser C3A t0 the grid of the valve V35 of the
to glow. This tube will, however, glow after the 50 toggle circuit SIC. This toggle circuit is con
normal extinguishing pulse has been fed there
sequently transposed and the neon tube NTC
to by the multivibrator SSP and consequently
is lighted. The circuit »remains in this condi
no pulse will be fed to SIC. In this condition,
tion until relay IAR is again operated when re
therefore, the neon tube NTB remains lighted.
sistance earth is connected in place of direct
Thus if the condenser is within the specified
earth to the cathodes of the valves V30, V32 and
limits, the neon tube NTC remains lighted while
V34 thus causing any operated toggle circuit to
if the value is less than the lower limit the neon
be restored to normal.
tube NTA remains lighted, and if it is greater
It will now be assumed that the Value of the
than the maximum limit the neon tube NTB
condenser under test is below the lower of the
remains lighted.
60 specified limits. In this case the multivibrator
Referring now to Fig. 4 which shows the
SSO will revert to normal before the multivibrator
circuits in detail, the multivibrators SSN, SSO
SSN. When the multivibrator SSO reverts, a
and SSP are similar to the multivibrator SSA
negative pulse will be applied via condenser
shown in Fig. 2 while the indicating vor toggle
C31 to the grid of V30 but vwill be without effect
circuits SIA, SIB and Slo are similar to the 65 since this valve is non-'conducting at this time.
toggle circuit SI shown in Fig. 2, and rare also
The negative-going pulse subsequently obtained
arranged to respond only to negative-going im
from the multivibrator SSN Ywill be applied via
pulses, the negative bias applied to the control
condenser C30 to the grid .of valve V31 and will
grids being sufñciently large to prevent trigger
cause the toggle circuit SIA to be transposed as
ing by any of the positive-going impulses ap 70 previously described. The neon tube NTA is,
plied thereto.
The condenser under test is `connected be
tween terminals 3I and 32 in the multivibrator
SSO and it will be understood that the normal
condition of the multivibrators is with the
therefore, lighted and remains lighted since the
pulse which would normally cause its extinction
has already been received and has been without
'eiîect .Further when the multivibrator lSSP re
verts 'to normal a .negative pulse will be applied
2,601,492
8
via condenser C33 to the grid of V32 and this again
the upper of the two limiting values, means in
will be without effect since the valve V32 is non
conducting at this time. The neon tube NTA,
for generating at a time subsequent to the de
cluding said resistor and capacitor combination
velopment of said start signal a third pulse which
is indicative of the value of the component under
pulse is provided on the operation of relay IAR.
test, an indicating circuit, means for applying all
If the Valve of the condenser` under test is
of said iirst, second and third pulses to said indi
above the upper speciñed limit, the multivibrator
cating circuit and means for operating said indi
SSN will ñrst revert and cause the lighting of
cating circuit to indicate whether said third pulse
the tube NTA as previously described. In this
case the second multivibrator to revert will be 10 is applied to the indicating circuit after the appli
cation of said first pulse and before the applica
SSP whereupon a negative-going impulse is ap
tion of said second pulse.
plied via C33 to the grid of V32. This will be
2. Circuit arrangements for testing resistors
without effect since the valve V32 is non-con
and capacitors and for indicating whether the
ducting at this time. When the multivibrator
value of the component under test is between
SSO finally reverts, the neon tube NTA will be
upper and lower limiting tolerance values com
extinguished and a negative-going pulse will be
prising a time-constant circuit including a com
fed from SIA via C32 to the grid of V33 and the
bination of resistor and capacitor elements, one
circuit SIB will be transposed to cause the light
of which elements constitutes the component
ing of the neon tube NTB and this tube will re
main lighted until the resetting pulse is ob 20 under test, means for generating a start signal,
means for generating a first pulse a predeter
tained by the operation of relay IA.
minable time after said start signal to establish
With regard to the generation of the start
the lower oi the two limiting values, means for
pulse, this is provided by a circuit which enables
generating a second pulse at a different prede
repetitive measurements to be effected automat
terminable time after said start signal to estab
tically and consists of an interrupter circuit
lish the upper of the two limiting values, means
comprising relays IGR and IAR. Relay IGR
including said resistor and capacitor combina
may, for instance, consist of a type of relay
tion for generating at a time subsequent to the
known as a galvanometer relay having a pair
generation of said start signal a third pulse which
of cobalt steel magnets forming an astatic com
bination, one of the magnets being almost com 30 is indicative of the value of the component under
test, a normally closed gate circuit, means for
pletely enclosed by a pair of deflection coils.
opening said gate circuit in response to the gener
The periodic time of oscillation of the magnets
ation of said iirst pulse, means for closing said
is controlled by a spiral hair spring and a robust
gate circuit in response to said second pulse,
silver contact IGRI is arranged to close at the
means for applying said third pulse to said gate
end of the return swing, the hair spring being
circuit and indicating means connected to said
selected so that the galvanometer relay delivers
gate circuit and operated in response to the appli
one pulse every two seconds. The closure of con
cation of said third pulse to said gate circuit
tacts IGRI closes the circuit for relay IAR which
while said gate circuit is open.
at contacts IARI completes the circuit for the
3. Circuit arrangements for testing resistors
coils of the galvanometer relay in order to main 40
and capacitors and for indicating whether the
tain the oscillation. Relay IAR in operating in
value of the component under test is between two
addition at contact IAR-2 connects a resistance
limiting values comprising a time-constant cir
earth instead of direct earth to the cathode cir
cuit including a resistor and a capacitor in com
cuit of the normally non-conducting valves of the
bination, one of which constitutes the compo
indicating circuits thus restoring any of these
nent under test, a control circuit operating nor
valves which may be conducting and setting the
mally to charge said capacitor, a cyclic electronic
indicate circuits to normal. When relay IAR re
counter, a source of accurately timed pulses for
leases, relay IBR operates and as explained
driving said counter, means in said control cir
above, at contact IBRI provides the start pulse
cuit for initiating the discharge of said capacitor
for the circuits SSN, SSO and SSD. This opera
in response to the ñrst impulse of a cycle de
tion proceeds continuously a test taking place at
livered to said control circuit from said electronic
each operation of relay IBR so that repetitive
counter, a normally closed gate circuit having
testing is possible. In operation the voltage sup
an input circuit and an output circuit, means
ply is ñrst switched on and the key IKA is mo
therefore, remains lighted until the resetting
mentarily operated to cause the initial operation ,
of relay IGR. After this operation relays IGR,
íAR and IBR interact continuously and a con
denser such as C35 may be connected between
terminals 3I and 32 on the front panel at any
responsive to subsequent pulses delivered by said
counter respectively for opening and closing said
gate circuit, means in said control circuit for
applying a pulse to the input to said gate circuit
when the voltage across said capacitor reaches
time and repetitive readings of the value of the 60 a predeterminable value, an indicator circuit con
nected to the output of said gate circuit and
condenser will continue to be given as long as
means responsive to the arrival of said pulse from
the condenser is connected to the terminals.
said
control circuit at the input to said gate cir
I claim:
cuit while said gate circuit is open for delivering
l. Circuit arrangements for testing resistors
and capacitors and for indicating whether the « a pulse to said output circuits for operating said
indicator.
value of the component under test is between two
4. Circuit arrangements for testing resistors
limiting values comprising a time-constant circuit
and capacitors and for indicating whether the
including a combination of resistor and capacitor
value of the component under test is between two
elements one of which elements is the component
limiting values comprising a first relaxation cir
under test, means for generating a start signal,
cuit having one stable and one unstable condition
means for generating a iirst pulse a predetermin
of equilibrium, a time-constant circuit including
able time after said start signal to establish the
resistance and capacitor elements of which one
lower of the two limiting values, means for gen
comprises the component to be measured and is
erating a second pulse at a different predeter
minable time after said start signal to establish 75 included in the circuit determining the relaxation
2,601,492
9i
period: of said first relaxation circuit. means for
charging said capacitor with said first relaxation
circuit in the stable condition, a cyclic electronic
counter, a source of accurately timed impulses
for driving said electronic counter, means respon
sive to the first impulse of a cycle delivered by
said electronic counter for changing overr said
first relaxation circuit thereby 'initiating the dis
10
responsive to the changeover of said second re
laxation circuit from said second to said ñrst
stable condition for applying a gate closing volt
age derived from said voltage source to said gate
CII circuit, means responsive to the changeover of
said first relaxation circuit from the unstable
to the stable condition for applying a pulse to the
input circuit of said gate circuit, an indicator
charge of said condenser, a second relaxation
connected to the output of said gate circuit and
circuit having two stable conditions of equilib 10 means responsive to the arrival of said pulse from
rium, means responsivey to a subsequent impulse
said ñrst relaxation circuit at said gate circuit
at a time when said gate circuit is open for
of a cycle from said electronic counter for chang
delivering a pulse through said output circuit to
ing over said second relaxation circuit from one
operate said indicator.
stable condition to the second, a normally closed
'7. Circuit arrangements for testing resistors
gate circuit having an input and an output, means
and capacitors and for indicating whether the
responsive to the changeover of said second relax
value of the component under test is between
ation circuit for opening said gate circuit, means
responsive to the last impulse of a cycle delivered
two limiting values, one above and one below an
optimum value, and if not whether it is above or
by said electronic counter for changing over said
below said optimum value comprising a time
second relaxation circuit from the second stable
constant circuit including resistor and capacitor
condition to the ñrst, means responsive to the
elements of which vone constitutes the component
last changeover of said second relaxation circuit
for closing said gate circuit, means for applying
to be tested, a ñrst, a second and a third control
circuit, means for simultaneously operating all
a pulse to the input of said gate circuit when
said control circuits, means for causing said ñrst
said first relaxation circuit reverts to the stable
‘ control circuit tol revert to the unoperated con
condition in response to a predeterminable change
dition after a time period measuring the lower
in the voltage across said capacitor, an indicator
of said limiting values, means for causing said
circuit connected to the output of said gate cir
second control circuit to revert to the unoper
cuit and means responsive to the arrival of said
pulse from said ñrst relaxation circuit at said 0 ated condition after ,a period measuring the
upper of said limiting> values, means including
gate circuit at a time when said gate circuit is
open for delivering a pulse through said output
said time-constant~ circuit for causing said third
control circuit to revert to the unoperated con
circuit to operate said indicator circuit.
5. Circuit arrangements as claimed in claim 4
dition after a time period which is substantially
a measure of the optimum value of the com
ponent to be tested, a ñrst, a second and a third
indicator means, means for operating said ñrst
indicator means at time periods when the third
is non-conducting in the stable condition of the
control circuit reverts to the unoperated con
relaxation circuit.
40 dition prior to said first and second control cir
6. Circuit arrangements for testing resistors
cuits, means for operating said second indicator
and capacitors and for indicating whether the
means at time periods when the third control
value of the component under test is between
circuit reverts to the unoperated condition sub
wherein said indicator circuit comprises a re
laxation circuit having a stable and an unstable
condition of equilibrium and a discharge tube
connected to the anode circuit of the tube which
two limiting values comprising, a first relaxation
sequent to the ñrst control circuit and prior to
the second control circuit and means for operat
ing the third indicator means at time periods
when the third control circuit reverts to the
unoperated condition subsequent to each of the
constant circuit forming a part of the circuit
second and third control circuits.
determining the relaxation period of said first 50
.8. Circuit arrangements for testing resistors
relaxation circuit, means for charging the capac
and capacitors and for indicating whether the
itor of the time-constant circuit during the
value of the component under test is between
stable condition of the said relaxation circuit,
two limiting values and if not whether it is above
a second relaxation circuit having first and
or below said limiting values comprising a time
second stable conditions of equilibrium, a cyclic 55 constant circuit including a resistor and capaci
electronic counter, a source of accurately timed
tor combination, of which one is the component
pulses for driving said counter, means for trans
to be tested, first, second and third control re
mitting the first pulse in a cycle from said elec
laxation circuits each having one stable and one
tronic counter to said ñrst relaxation circuit to
unstable condition of equilibrium, means for
circuit having a stable and an unstable condition
of equilibrium, a time-constant circuit including
resistor and capacitor elements of which one
element is the component under test, said time
change over said relaxation circuit to said un
60 simultaneously changing over said ñrst, second
stable condition and thereby to initiate the dis
and third relaxation circuits from said stable to
charge of said capacitor, means for transmitting
said unstable condition, a relaxation period de
subsequent pulses in the same cycle from said
termining circuit for said first relaxation con
electronic counter to said second relaxation cir
trol circuit for causing said circuit to revert to
cuit to change over said second relaxation circuit 65 said stable condition in a time representative of
from said ñrst stable condition to said second
the lower of said two limiting values, a relaxa
stable condition and back to said ñrst stable con
tion period determining circuit for said second
dition respectively, a normally closed gate cir
relaxation control circuit for causing said cir
cuit controlled by said second relaxation circuit
cuit to revert to said stable condition in a time
and having an input circuit and an output cir 70 representative of the upper of said two limiting
cuit, a voltage source, means effective upon
values, a relaxation period determining circuit
changeover of said second relaxation circuit
for said third relaxation control circuit including
from said ñrst to said second stable condition
the resistor and capacitor combination time-con
for applying to said gate circuit a gate opening
stant circuit for causing said circuit to revert to
voltage derived from said voltage source and 75 said stable condition in a time representative of
2,601,492
12
11
condition and a fifth connection between said
second relaxation indicator circuit and said third
relaxation indicator circuit for transmitting a
each having a normal first condition of stable
pulse to change over said third relaxation indica
equilibrium and a second condition of stable
equilibrium, a ñrst connection between said first in tor circuit from the normal to the second condi
tion on the changeover of said second relaxation
relaxation control circuit and said first relaxa
indicator circuit from the second condition to
tion indicator circuit for transmitting a pulse on
the normal condition.
the reversion of said ñrst relaxation control cir
9. Circuit arrangements as claimed in claim 8
cuit to the stable condition to change over said
ñrst relaxation indicator circuit from the nor 10 comprising a cyclically-operated relay set in
cluding at least two interacting relays, contacts
mal stable condition to the second stable con
controlled by said relay set, means responsive to
dition, a second connection between said third
the operation of one contact at the beginning of
relaxation control circuit and said ñrst relaxa
a cycle for simultaneously operating said control
tion indicator circuit for transmitting a pulse on
circuits and means responsive to the operation
the reversion of said third relaxation control cir
of another contact at the end of a, cycle for
cuit to the stable condition to change over said
triggering said relaxation circuits from the sec
ñrst relaxation indicator circuit from the second
the value of the component under test, first,
second and third relaxation indicator circuits
stable condition to the normal stable condition,
ond stable position back to the first.
GEORGE THOMAS BAKER.
a third connection between the second relaxation
control circuit and said second relaxation indi 20
lcator circuit for transmitting a pulse on the re
REFERENCES CITED
version of said second relaxation control circuit
The following references are of record in the
to the stable condition to change over said sec
ille of this patent:
ond relaxation indicator circuit from the second
UNITED STATES PATENTS
stable condition to the normal stable condition, 25
Number
Name
Date
a fourth connection between said first relaxation
2,044,424
Edwards et al. ____ June 16, 1936
indicator circuit and said second relaxation in
dicator circuit for transmitting a pulse to change
over said second relaxation indicator circuit from
the normal to the second condition on the 30
changeover of said ñrst relaxation indicator
circuit from the second condition to the normal
2,408,727
2,445,584
Blitz ____________ __ Oct. 8, 1946
Ramo __________ __ July 20, 1948
2,504,848
2,544,685
Kunz ____________ __ Apr. 18, 1950
Jackson ________ __ Mar. 13, 1951
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