1. hobbies and interests
2. inventors and patents

Feb. 5, 1952
A. s. FITZ GERALD
2,584,856
ELECTROMAGNETIC SYSTEM
Filed Dec. 51, 1946
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Feb- 5, 1952
‘A. s. FlTZ GERALD
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ELECTROMAGNETIC SYSTEM
Filed Dec. 51, 1946
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BY
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Feb. 5, 1952
2,584,856
A. S. FITZ GERALD
ELECTROMAGNETIC SYSTEM '
Filed Dec. 31, 1946
4 Sheets-Sheet 4
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INVENTOR
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AMBZJ, ATTORNEYS
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Patented Feb. 5, 1952 _
2,584,855
UNITED __STATES PATENT OFFICE
2,584,856
ELECTROMAGNETIC SYSTEM
Alan S. Fitz Gerald, Wynnewood, Pa., assignor to
Warren Webster & Company, Camden, N. J.,
a corporation of New Jersey
Application December 31, 1946, Serial No. 719,445
12 Claims. (Cl. 323-89)
1 .
This invention relates to magnetic amplifying
systems of the type which employ saturating
reactors, and more particularly to systems of the
above type which respond selectively in accord
ance with the polarity of a direct current input
signal.
whereby the output current of onepis increased
and the output current of the other is decreased
by application to the input windings of saturat
ing current of a given polarity. Means, mechan
7 ical or electrical, are provided for actuating a
work-device in accordance with the difference
between the output current of the two magnetic
The present invention constitutes an improve
ment on that forming the subject matter of my
ampli?ers.
co-pending U. S. application, Serial No. 666,867,
In other words, the output or one magnetic
?led May 3, 1946, now Patent No. 2,461,046. In 10 ampli?er is balanced against the output of. the
this earlier application, I have disclosed a mag
other and the work-device is operated by the
netic ampli?er system primarily intended for
out-of-balance effect.
furnishing an electrical output to operate a single
In devices of the above described form, where
electro-responsive device such as a relay or the
a high order of sensitivity is required, it follows
like, that is to say. a simple single action device 15 that the out-of-balance current represents a very
which will, for example, close a contact when
small percentage of the magnitude of the two
energized and open it when deenergized.
currents which are balanced. Thus, the utility
The more important electrical control systems,
of arrangements of this nature is limited mostly
in connection with which there is a requirement
by questions of stability; that is to say, the ex
for sensitive amplifying or responsive devices 20 tent to which small differences between the two
capable of operation with inputs of very low
balanced currents, of an order of magnitude com
power level, are of the type represented by auto
parable to that which may be produced by an '
matic self-balancing bridges, servo-mechanism
input current, can arise from causes other than
circuits, and automatic regulating or similar
an input signal.
systems having a normal condition of balance
In practice it has been found that such differ
' or stability from which deviations are possible
ences can readily arise due to differences between
in more than one sense; as for example, high or_
different recti?ers, or di?erent high permeability
low, fast or slow, leading or lagging.
' magnetic cores, and especially as a resul. of hue;
In such arrangements, the sensitive device
tuations in the alternating current supply volt
must be responsive selectively in accordance with
age, temperature effects, and the like.
the sense of the unbalance or deviation, and the
In other words, the condition of perfect bal
output delivered must be of the form permitting
ance or zero adjustment of such high-sensitivity
action in either of two corrective directions as
ampli?ers is subject to drift or deviation as a
well as a continued state of inaction as long as
result of any change that takes place in one por
the normal or balanced condition of the auto— _ LI tion of a magnetic ampli?er of this type which
matic regulation is maintained. For example,
the output must be capable of operating a motor
selectively in either of the two directions or of
causing the motor to remain at rest; or it must
is not exactly counter-balanced by a precisely
congruent change in the other portion. Such
ampli?ers therefore are subject to the limita- .
tions, well understood by those skilled in the art,
which apply‘ to all devices based upon the prin
ciple of detecting small differences between two
relatively large quantities.
actuate a relay or control device of-the so called
three-position type capable of closing one or
other of two contacts or causing both contacts
to remain open.
It is accordingly an object of my invention
to provide an improved magnetic ampli?er sys
It is therefore another object of my invention
to provide an improved polarized-type magnetic
tem of the polarized type capable of furnishing
an output selectively variable in accordance
with the polarity of the input signal.
In polarized type magnetic amplifiers of the
prior art duplicate arrangements are shown of
two ‘magnetic ampli?ers each of which furnish
output currents when no inputis applied to the
saturating windings. Input saturating current
.30
ampli?er in which the zero or null position is
more positive and stable than arrangementsof
the prior art, in that it is not primarily a tune
tion of a balance between relatively large outputs
of a pair of magnetic ampli?ers.
These and other novel features which I believe
to be characteristic of my invention will be set
forth with particularity in the appended claims.
My invention itself, however, both as to its or
is applied, in opposite sense, to the input wind
ganization and method of operation, together.
ings of the two duplicate magnetic ampli?ers, :: with further objects and advantages thereof, may
9,684,856
?ers are associated with marked non-linear char
acteristics, and that such devices are substantially
non-conducting, in either direction, at very low
voltages. Thearrangement shown in Fig. l is
in general practical and useful when the input
power is delivered from a circuit of relatively high
ance with‘ an embodiment of my invention;
resistance, to which value the resistance of SL
Fig. 2 is an electrical circuit diagram showing
and SR are properly commensurate, such that the
a more sensitive form of magnetic ampli?er in
minimum signal voltage is not less than say, 100
accordance with another embodiment of my in
millivolts. These conditions result, in practice,
10
vention;
'
in a limitation that the arrangement shown in
Fig. 3 is a diagram illustrating a modi?cation
Fig. 1 tends to be inapplicable for input power
of the embodiment of my invention shown in
levels very much less than 10 microwatts.
Fig- 2;
Magnetic ampli?ers, may, very readily be fur
Fig. 4 is a diagram showing a further embodi
nished for power levels substantially less than the
ment of my invention;
above mentioned ?gure.
Fig. 5 is a fragmentary portion of the Figure l
best be understood with reference to the follow
ing description taken in connection with the ac
companying drawings, in which:
Fig. 1 is an electrical circuit diagram showing
a single stage of a magnetic ampli?er in accord
I show, therefore, in Fig. 2 an improved ar
rangement operating upon a principle similar to
that shown in Fig. 1, but not subject to the above
Fig. 6 is a diagram representing a two-stage
magnetic ampli?er based upon the arrangement 20 limitation.
In Fig. 2, I show the two duplicate magnetic
shown in Figs. 1, 4 and 5; and
ampli?er systems comprising saturating reactors,
Figs. 7 and 8 are electrical circuit diagrams
transformers, and resistance, together with their
showing applications of the embodiment of my
respective output circuits all as shown in Fig. i.
invention illustrated in Fig. 6.
In Fig. 2, however, I obtain selective input to
Referring to the drawing, I show in Fig. 1 a
the D. C. saturating windings, in accordance with
magnetic ampli?er circuit comprising a duplicate
the polarity of the input signal, by the use of a
arrangement of the circuit shown in, Fig. l of
regenerative or feed-back arrangement.
my above cited co-pending application, in which
In Fig. 2, I employ the feed-back connections
I have used like numerals to identify the‘ core i
of the saturating reactor, the A. C. winding 2, the 30 which I have disclosed in Fig. 8 of my above cited
co-pending application.
saturating winding 3, together with the core 4,
It will be seen that in Fig. 2 of the present ap
the primary winding 5, and the secondarywind
plication
I show resistances UL and HR con
ing 8 of the transformer. I show also resistances
circuit illustrating a modi?ed form of my inven
tion;
'
l and 8, conductors 9, l0, and H, H, rectifiers l4,
nected in series with the input windings 3L, 3R,
and output circuits l5. In view of the fact that 35 and also connected to receive the direct current
delivered by the recti?ers ML, HR, to the output
all of these elements occur in duplicate, I have
circuits 15L, ISR.
identi?ed all those comprising the left hand por
tion of the circuit by the suffix L, and those in
the right hand portion of the circuit by the suf
?x R.
I show also an alternating current source at l3
I have, however, arranged the connections to
UL and HR so that the feed-back is positive in
respect of the left hand section of the magnetic
ampli?er when it is negative in respect of the
right hand section; and vice-versa.
from which both of the above described magnetic
Because of the necessary interconnection of the
ampli?ers are energized in parallel.
input and output circuits. I supply the two sec
In Fig. l, I show leads l8L, I8R, for receiving
input energization, and arranged to supply the 45 tions of the ampli?er through an isolating trans
former having a core 20, a primary winding 2|,
input windings 3L, 3B, in parallel, through two
and two secondary windings 22L, 22R respectively.
half-wave contact recti?ers, ISL, l9R, connected
It will be apparent to those skilled in the art
in opposite sense so that when the input is ap
that the action of the arrangement of Fig. 2 will
plied such that |8L is positive and 18R is negative,
such that when input is applied of such po
current is conducted by 19L to energize 3L. Un 60 be
larity that l8L is positive and IBR is negative, the
der this condition ISR does not conduct and 3R
left hand section of the magnetic ampli?er, of
is not energized. The right hand section of the
which the input winding is 3L, will have positive
circuit is therefore completely inert, and no out
feed-back; whereas the right hand section of the
put is delivered to the right hand output circuit
magnetic ampli?er of which the input winding is
I5R. The left hand output circuit l5L is, how
3R will have negative feed-back.
ever, energized commensurately with the input
‘Under these conditions the left hand output
signal.
circuit [5L will be energized but no current will
If the polarity of input signal is reversed so as
be supplied to the right hand output circuit ISR.
to make [8R positive‘ and ISL negative, the op
I wish particularly to point out that, this effect
60
posite effect results; output circuit HR is ener
is brought about almost entirely by selective en
gized whereas no current is supplied to the out
put circuit I5L.
It will be obvious to those skilled in the art
that according to this arrangement the zero
ergization of the windings 3L, SR and is to a min
imum extent affected by, or dependent upon,
the electrical characteristics of the saturating re
point of the system is entirely independent of 65 actors, transformers, resistances, recti?ers, etc.
It is important to note that the selective action
the characteristics of the recti?ers ML and HR
produced is not merely the expected result of
and is likewise independent of changes in the
the separate actions of two ampli?er circuits in
electrical characteristics of any of the other cir
accordance with Fig. 8 of my co-pending applica
cuit elements, such as the saturating reactors,
transformers, or resistances. The zero point is 70 tion; nor is it simply the sum of the results con
tributed by the two circuits. The feed-back
directly related to the change of polarity of the
action
is very much more selective when the two
input, in accordance with the action of HL and
input windings 3L, 3R, are connected in parallel,
ISR.
It is well known to those skilled in the art that
the polarity-selective properties of contact recti
inasmuch as the ampli?er circuit, in respect of
which positive feed-back obtains, tends to cause
acetone
5
substantially all of the signal current to ?ow
in the input winding of the saturating reactor
0! that ampli?er, as a result of which it is
possible to .obtain a condition substantially the
same as that, shown in Fig. 1'. That is to say,
with a signal of one polarity one input winding
is energized and the other substantially deener
gized, this energy relationship with reference to
3L and JR being reversed when the input polarity
is reversed.
'
Thus there is a Joint or co-operative action
between the two magnetic ampli?er circuits of
a distinctive character which does not occur when
0
'
"
-
;
.
or less, it will readily be apparent that the power
delivered to the magnetic ampli?er for one per
cent out-of-balance will be of a very low order.
On the other hand, conditions can occur, as
for example, following a temporary failure of the
power source, invwhich the whole system may be
energized with the bridge in the extreme con
dition of out-of-balance as a result of which
power levels of the order of 10,000 times the
desired minimum response level can occasionally
be applied to the input.
Under such condition the limitations of an
arrangement such as that shown in Fig. 2 would
either of said circuits are operating individually
become apparent in the following manner.
and separately.
Supposing that a very high input be applied
Thisarrangement is responsive to input power 15 to conductors I8L, IIR such that the former is
levels substantially less than that shown in
positive and the latter negative. Under this
F18. 1.
condition, output circuit ISL would receive sub
In Fig. 3 I show an arrangement similar to Fig.
stantial output. While it would be desired that
2 but in which I have included, in addition, feed 20 output circuit I5R should be entirely una?ected
back windings, as in Fig. 7 of my above cited co
by an input of this polarity, if the input attain
pending application, Serial No. 666,867. v
a su?lciently high level some output current
These windings which I have designated by like
might commence to appear in I5R. Since it
identifying numerals I6L, IBR improve the
operation of my invention.
In order to simplify the drawing I have trans
posed the order of series connection of the input
winding 3R. and the feed-back resistor "R. so
as to avoid crossing oi’ conductors in the diagram.
is contemplated that the outputs of ISL, I5R
25 are to energize further stages of ampli?cation,
even low values of output on the side with respect
to which no e?ect is desired, are inadmissible.
I therefore show in Figs. 4, 5, and 6, structure
which accomplishes the desired object. That is
to say, a magnetic ampli?er capable of polarized
HR is reversed. But no change in operation or 30 response, high sensitivity, and capable of correct
" For the same reason the- sense of the recti?er
function is thereby entailed.
'
‘
operation over a wide range of input levels.
In Fig. 4, I show an arrangement substantially
IiR, as shown in the diagram, should be con
similar to Fig. 3 except in respect of the manner
nected additively with reference to the action
in which the outputs of the recti?ers “L, “R
of their associated feed-back resistors “L, "R. 35 are connected. Instead of the two separate out
While this selective action in accordance with
put circuits I5L, ISR, I connect the output cir
the D. C. polarity of the input is very marked, it
cuits of the recti?ers I4L, I4R additively in
is somewhat limited in its range of operability.
series, including in this series circuit two re
That is to say, the constants of the circuit may
sistors of like value, 23L, 23R. This series cir
- be adjusted to give de?nite selectivity for any 40 cuit therefore includes the direct current con
given input magnitude; but there is a tendency
neotions of the recti?ers ML, “R, the resistors
towards imperfect action at other input levels.
23L, 23R, the feed-back windings, ISL, IGR, and
For example, if the circuit is adjusted for best
portions of the input circuit including the feed
operation at low input levels ,it will tend to
back resistors I'IL, I'IR.' In Fig. 4, I show a
operate less effectively at high inputs. Con 45 junction point 24 between 23L and MR, and
versely it can be set so as to give very de?nite
another junction point 25 between I‘IL and HR.
It is to {be noted that fed-back windings ISL,
selectivity with high input levels. But when
so arranged it will not function so well with
To these junction points I connect conductors
I80L and “MR.
I
low values of input.
It will be apparent to those skilled in the art
In systems of the type hereinbefore described 60 that with this method of connection, when the
in connection with which the use of the present
rectified currents delivered by ML, “R are exact
invention is contemplated it is an inherent con
ly equal 24 and 25 will be equi-potential points
dition that the input levels at which normal
and no output will be delivered by conductors
action is required are of a low order; that is to
IlIiL, I80R.
‘
say, a high sensitivity is essential. On the other 55
If, however, the output of HR be greater than
hand, conditions, not existing in normal action,
but not entirely avoidable, may occur as a result '
that of “L, which condition, it will 'be noted,
occurs when the conductor I8R is positive, then
24 will become positive with relation to- 25. Thus
occur.
\
conductor
"0R will become positive with re
Consider for example, any representative type 60
spect of I80L. ‘If, on the other hand, input is
of self-balancing bridge or servo-mechanism such
applied to IBL, IBR, such that I8L is positive
as for example, the arrangement in my U. S.
then, in like manner I80L will become positive
Patent No. 2,277,849. In such applications it
with respect to IBUR.
may reasonably be required that the system be
It is to be noted that with this arrangement, if a
maintained in a condition of balance within, say,
very high input be applied to the magnetic am
one per cent, at least, of its full range of opera
pli?er, such that, as described above, there may
tion. From this it follows that the input power
level at which the magnetic ampli?er is desired
be' some small output current in respect of the
to be operative will be less than one ten-thou
side where none is desired, the conductors I80L
sandth of the power level at which the bridge is 70 and “NR will still deliver output of the correct
of which, relatively, very high input levels may
energized.
.
If, as may well be the case, there are limiting
polarity.~ This is because the conductors I80L,
I80R are energized in accordance with the differ
conditions, as for example, temperature rise,
ence between the left and right hand elements of
tending to restrict the power dissipation in the
the magnetic ampli?er; and, even if there is
bridge to magnitudes of the order of a few watts 76 some small undesired current-on one side, the
assume
1
-
-
.
current on the other side is very much greater.
The amplifying action of an arrangement as
shown in Fig. 4 is such that the‘power level is
stepped up to an extent that if an input applied
with the recti?er with respect to which reverse
conductivity is in question, is in opposition to
to ISL, IUR be of a magnitude not applicable to
the arrangement shown in Fig. 1, ‘that is to say,
the reverse conductivity. This tends to suppress
the reverse conductivity.
Thus the arrangement of Fig. 5 both improves
the sensitivity and increases the range of effec
there would not be su?icient voltage to cause
tive operation.
'
=.
By making the connection between IUR and
ISL, ISR. to become conducting, nevertheless, the
the mid-point of 2S adjustable, if it be desired
output delivered by IBOL-and I80R would be of
sufficient magnitude. 1 may therefore connect 10 to predispose the action of the ampli?er in one
direction or the other, this may be accomplished
conductors I801‘, IGOR to a second stage of mag
by varying the position of this connection so
nétic ‘ampli?cation in accordance with Fig. 1,
as to produce the desired result.
with entirely effective results.
In Fig. 6, I show a complete magnetic ampli
I show in Fig. 5 an arrangement which permits
?er unit 15 comprising an assembly of the struc
of an improvement in the action of the half
to Fig. 1.
Referring to these half-wave rectifying ele
ture disclosed in Figsl, 4, and 5.
In the ?gure I show a pair of input binding
posts 32L, 32R to which the input conductors
ments, it is known to those skilled in the art
I8L, I8R of a ?rst stage substantially identical
wave rectifiers ISL, IBR as described in reference
that such contact recti?ers as are now available 20 with the arrangement shown in Fig. 4, are con
are neither perfect conductors in the forward
nected.
I show also a second stage substan
direction nor perfect insulators in the reverse
tially in accordance with Fig. 1, and two pairs
direction. The merit of a contact recti?er in
of binding posts, 34L, “R to which the output
heres in the ratio of the resistances in the for
circuits ISL, ISR are connected.
ward and reverse directions. I have found that 25
Included between the output conductors I80L,
recti?ers of the copper oxide type, such as are
IIIDR of the ?rst stage and the input windings
currently available, when used in the arrange
ment shown in Fig. 1, will furnish a sensitivity
3L, 3R of the second stage I show the resistor
26 and the associated structure disclosed in
of several microwatts; but with high values of
Fig. 5.
input their conductivity in reverse direction be 30
I show also a pair of binding posts 33 for re
comes appreciable. I ?nd that recti?ers of the
ceiving the A. C. supply to the magnetic ampli
selenium type have a much better ratio of direct
?er. Conductors IIL, I2L, IIR, IIR are con
and reverse conductivity and even with high
nected to the binding posts 33 as is also the
input power levels they are superior in respect
primary winding II of the isolating transformer
of reverse conductivity. However, the forward
for supplying the second stage. I provide the
conductivity of the copper oxide recti?er is better '
isolating transformer with an additional sec
than that of the selenium type. That is to say,
ondary winding 30 connected, as shown in the
a high value of input voltage is necessary be
drawing, to supply the recti?er 21.
fore the selenium type recti?er becomes effec
In cases where exceptionally high input power
tively conducting. Thus, if a selenium type recti
levels may be encountered, I may include, con
?er be used the amplifier will require an input of
nected across the binding posts 32L, 32R, a.
from 20 to 50 microwatts before any substantial
limiter 3|. This latter feature by itself will not
gain is developed.
be su?icient to protect the magnetic ampli?er
In Fig. 5 I show a resistor 26 included in the
connections to the input windings 3L, 3R. I con
from the effects of high input levels since such
nect the input conductor I8R to the mid-point of
the resistor 26. Thus an input current supplied
through I8R to 3L or 3R flows in opposite sense
through the two sections of 26. Direct current
from any convenient source, as for example,
a device does not commence to become conduct
ing to a substantial extent until a relatively high
voltage is applied to the binding posts 32L, 32R.
an A. C. source 29, is caused to flow in the re
For this reason, the other arrangements herein
before disclosed are desirable. However, if suffi
ciently high power levels are reached the use of
the limiter 3I may be an additional advantage.
While I have shown in Fig. 6 only one addi
sistor 28. The polarity of this direct current as
shown in Fig. 5 is such that the E. M. F.’s set
tional neutral type stage of amplification fol
lowing the ?rst stage, it is to be clearly under
recti?er 21, energized through a resistor 28, from
up thereby in the two sections of 26 are additive
in respect of conductivity in the forward direc
tion of ISL, ISR respectively.
‘The effect of this arrangement is two-fold.
stood that one or more additional stages con
nected between the output circuits ISL, I5R and
the binding posts 34L, “R, as shown in Fig. 6
of my co-pending application, Serial No. 666,867,
may be included.
The value of the resistor 28 is so adjusted that,
I show in Figs. 7 and 8 the manner of use of
when there is no input applied to I8L, IBR, no 60
the magnetic ampli?er assembly 35.
substantial ?ow of current takes place in 3L, 3R.
In Fig. '7 I show arrangements appropriate
However, when such an input is applied, because
for the control of a direct current motor and
of the voltages initially present, due to 26, in
in Fig. 8 the arrangements which may be used
this circuit substantially less input applied to
I8L, I8R will give rise to appreciable current in 65 for an alternating current motor.
In Fig. 7 I show a motor of the split-series
3L, 3R. In one such arrangement which I have
type having an armature 36, ?eld windings 31L,
constructed the use of this feature reduced the
31R, energized from a source 38 through con
minimum effective power level from about 50
tacts 39L, 39R of a relay 4. having coils ‘IL,
microwatts to substantially less than 10 micro
watts.
70 AIR. The coils IIL, “R are connected respec
tively to binding posts 3lL, 34R.
Furthermore, in addition to this effect, when
The action of my invention is as follows. ‘
an input of a high power level such that in
With no input applied to the binding posts
cidence of reverse conductivity in ISL or ISR
32L, 32R, the currents in both “L and “R. will
may become apparent, it will be noted that the
E. M. F. in the section of 26 which is in series 75 be inappreciable. If input be now applied to
2,584,866
the amplifier oi’ such polarity that binding post
32B is positive, substantial current will flow in the
relay coil HR. But there will be no effect at
all in respect of ‘IL. Accordingly the relay will
close contacts 39R and the motor will rotate in
the desired direction.
10
sisting of approximately 0.75" stacking of 3 limb
laminations of proportions similar to that shown
in Fig. 2 o! my aforementioned co-pending ap
plication Serial No. 666,867 having overall dimen
sions approximately 2.88" by 2.69" wide. The
center limb was 0.75" and the two outside limbs
Conversely if theinput polarity be reversed,
were
0.438" wide. The stamping had a window
the current will flow in ‘IL but not in HR and
area of 1.13 square inches. The laminations for
the motor will rotate in the opposite direction.
I wish particularly to point out that with this 10 the ?rst stage were made from a nickel-iron alloy
containing more than 70 per cent of nickel. The
structure, as distinguished from arrangements
cores of the second and third stages were made
of the prior art, there is no feature or function
from a nickel-iron alloy containing 50 per cent
of comparison or mechanical balance between
or
less of nickel. The cores 4 of the transformers
the excitation of “L, ll R. If desired, two sepa
rate relays could be used instead of the type ll 4, 5, 6, of all of the stages were constructed of
0.75" stacking of laminations 1.88" x 1.56" wide
shown in the drawing without any di?erence in
made
of convention I transformer core material.
the operation of my invention. In Fig. '7, I have
The resistance of the input circuit [at ter
shown the relay 40 in accordance with conven
minals 32L, 32R was of the order of 100 ohms
tional practice in the art. It is well known that
and
with suitable windings and resistance values
when a reversing motor is to be controlled by
an input of 50 microamperes corresponding to a
a contact device the contacts should be me
power level of approximately V4 of a microwatt
chanically interlocked in case of sticking or
caused a current of 20 milli-amperes to flow in
welding of the contacts.
the circuit connected to 34L or 34R. in accordance
In Fig. 8, I show a similar arrangement for
controlling a motor of the alternative current 25 with the polarity of the input. In this case the
resistance of the circuits supplied by ML, MR
induction type having a rotor 42, windings 43L,
"R, and a capacitor 44, energized from an A. C.
source 45.
was also of the order of 100 ohms. Thus the
power level of the output was approximately 40
milliwatts.
The motor windings are energized in series
Effective selective action was maintained with
with A. C. windings 200L, 200R of a pair of 30
input power levels exceeding ten thousand times
saturating reactors having cores I 00L, IO0R pref
the minimum response value.
erably of the type shown in Fig. 3 of my co
Although I have chosen a particular embodi
pending application Serial No. 666,867.
ment of my invention for the_purpose oi.’ expla
These two control reactors have D. C. satu
rating windings 3001i, 300R connected respec- . nation, many modi?cations thereof will be appa
rent to those skilled in the art to which it per
tively to binding posts 34L, 34R of the magnetic
amplifier 35.
tains. My invention, therefore, is not to be
limited except in so far as is necessitated by the
The action of the arrangement shown in Fig. 8
prior art and the spirit of the appended claims.
is similar to that already described in reference
What I claim as new and desire to secure by
to Fig. 7. According to the polarity of the D. C. 40
Letters Patent of the United States is:
input applied to binding posts 32L, 32R, one of
1. In combination, a magnetic ampli?er sys
the saturating windings 300L or 300R is, selec
tem comprising a ?rst stage consisting of a pair
tively, energized, the other remaining unaffected.
of magnetic ampli?ers each having an input
While the two saturating reactors in Fig. 8
circuit and an output circuit, a direct current
may be included in the magnetic amplifier as
sembly 35, I prefer to provide them in the form 45 source of reversible polarity and means for caus
ing said input windings to receive unequal en
of separate units. Thus the magnetic ampli?er
ergization from said source in accordance with
assembly 35 may without change be utilized
the polarity of said source, means connecting
either for the purpose of Fig. 7 or for an arrange
ment according to Fig. 8. Furthermore,‘ where 60 said output circuit in additive sense in series,
and means connecting normally equi-potential
an alternating current motor is controlled by
junction points between said output circuits for
saturating reactors in the manner shown in Fig.
deriving from said junction points direct current
8 there is necessarily a cognate relationship be
output of reversible polarity in accordance with
tween the type of motor used and the number of
the polarity of said source, together with a second
turns in the A. C. windings 200L, 200R. Thus,
in the arrangement shown, different types of 65 stage consisting of a further pair of magnetic
ampli?ers each having a direct current input
control saturating reactors for operation with
winding in a series circuit with boundary layer
motors of different voltages or different types
rectifying means and an output circuit, means
may be employed without changing the structure
connecting the series circuits of said D. C. input
of the magnetic ampli?er circuit 35.
60 windings in parallel to said junction points, for
In order better to illustrate the action of this
causing said last-mentioned input windings to
circuit, I give below some typical numerical values
receive unequal energization from said junction
taken from a practical embodiment of my in
points in accordance with the polarity derived
vention which I have constructed and tested.
from said junction points.
It should, however, be clearly understood that 65
2. Apparatus of claim 1 comprising means for
my invention may be carried into e?ect on any
improving the selective action with reference to
desired scale of magnitude and may be modi?ed
the polarity of said junction points consisting of
in any manner conformable with the purpose and
means for introducing in series with each of the
application for which it is to be employed. I
direct current input windings which are connect
am, therefore, in no way to be limited by the 70 ed to said junction points, a direct current E. M. F.
following data which is included only for the
in the same direction as that of forward flow in
purpose of facilitating the understanding of my
invention.
,
said boundary-layer rectifying means.
3. A pair of magnetic ampli?ers each having
In the aforementioned embodiment compris
an output circuit and a series input circuit com
ing three stages, all of the stages had cores, con— 76 prising a saturable core device having a direct
asaéasc
11
current input winding and a half-wave recti?er
connected in series with said input winding, and
means for connecting said series circuits in par
allel to a direct current source of reversible polar
ity for causing said input windings to receive
unequal energization from said source in accord
ance with the polarity of said source.
'
12
current source in accordance with the polarity
thereof.
8. A pair of magnetic ampli?ers each compris
ing: a saturable core device having an alternat
ing current winding and a direct current input
winding, 9. ?rst impedance, means for connect
ing said ?rst impedance in series with said al
ternating current winding across an alternating
current source, a transformer having primary
and secondary windings, a second impedance
10
a saturable core device having a direct current
connected in series with said primary winding
input winding, means for connecting said input
across said alternating current source, an out
circuits in parallel to a direct current source of
put circuit arranged to be energized responsive
reversible‘polarity, and means for interconnect
to ?ow of current in said alternating current
ing said input and output circuits for causing said
winding, and means for connecting said second
15
input windings to receive unequal energization
ary winding and said alternating current wind
from said source in accordance with the polarity
ing in series with each other and with‘ said out
of said source.
put circuit; means for connecting said input
5. A pair of magnetic ampli?ers each having
windings in parallel to a direct current source of
an output circuit and an input circuit compris
reversible polarity; and means energized from
ing a saturable core device having a direct cur
said output circuits for causing said input wind
rent input winding, means for connecting said
ings to receive unequal energization from said
input circuits in parallel to be energized from a
direct current source in accordance with the po
direct current source of reversible polarity, and
larity thereof.
means for energizing said input circuits from
9. A multi-stage magnetic ampli?er system
the output circuits of said magnetic ampli?ers
comprising: a ?rst stage comprising a 'pair of
whereby each of said windings receives a feed
magnetic ampli?ers each containing: a saturable
back effect of different polarity according to the
core device having an alternating current wind
polarity of said source for causing said input
ing and a direct current input winding, feed
windings to receive unequal energization from
back means connected in series with said input
80
said source in accordance with the polarity of
4. A pair of magnetic ampli?ers each having
an output circuit and an input circuit comprising
winding, a ?rst impedance, means for connect
the source.
6. A pair of magnetic ampli?ers each having
an output circuit and an input circuit comprising
a saturable core device having a direct current
ing said ?rst impedance in series with said ai
ternating current winding across an alternating
current source, a transformer having primary
and secondary windings, a second impedance
input winding, means for connecting said input 35 connected in series with said primary winding
circuits in parallel to be energized from a di
across said alternating current source, an output
rect current source of reversible polarity, and
circuit arranged to be energized responsive to
means for energizing said input circuits from the
?ow of current in said alternating current wind
output circuits of said magnetic ampli?ers where
ing, and means for connecting said secondary
by when said source is of one polarity one of
said input windings receives positive feed-back
and the other of said input windings receives
negative feed-back and when said source is
oi’ the opposite polarity said ?rst mentioned
input winding
receives negative teed-back
and said second mentioned input winding re
ceives positive feed-back, for causing said input
windings to receive unequal energization from
said source in accordance with the polarity of 60
said source.
,
7. A pair of magnetic ampli?ers each compris
winding and said alternating current winding in
series with each other and with said output cir
cuit, and means for interconnecting said output
circuit and said feed-back means; means for
connecting said series connected feed-back
means and direct current winding of one ampli
?er and said series connected teed-back means
and direct current winding of the other ampli
?er in parallel to a direct current source of re
versible polarity whereby said input windings re
ceive unequal energization from said direct cur
rent source in accordance with the polarity
ing: a saturable core device having an alternat
thereof; and a second stage comprising a fur
ing current winding and a direct current input
winding, 9. half-wave recti?er connected in
series with said direct current winding, a ?rst
impedance, means for connecting said ?rst im
pedance in series with said alternating current
ther pair of magnetic ampli?ers each having a
direct current input winding and an output cir
cuit and means connecting said ?rst stage with
winding across an alternating current source, a
prising: a saturable core device having an alter
nating current winding and a direct current in
put winding, teed-back means connected in se
ries with said input winding, a ?rst impedance,
means for connecting said ?rst impedance in se
transformer having primary and secondary
windings, a second impedance connected in
series with said primary winding across said
alternating current source, an output circuit ar
ranged to be energized responsive to flow of cur
said second stage.
‘
10. A pair of magnetic ampli?ers each com
ries with said alternating current winding across
rent in said alternating current winding, and 66 an alternating current source, a transformer hav
ing primary and secondary windings, a second
means for connecting said secondary winding
impedance connected in series with said primary
and said alternating current winding in series
winding across said alternating current source,
with each other and with said output circuit;
an output circuit arranged to be energized re
and means for connecting said series connected
recti?er and direct current winding of one am 70 sponsive to ?ow of current in said alternating
current winding, and means for connecting said
pli?er and said series connected recti?er and di
secondary winding and said alternating current
rect current winding of- the other ampli?er in
winding in series with each other and with said
parallel to a direct current source of reversible
output
circuit, means for connecting said series
polarity whereby said direct current windings
receive unequal energization from said direct 7‘ connected teed-back means and direct current
13
14
winding of one ampli?er and said series connect
ed feed-back means and direct current winding
of the other ampli?er in parallel to a direct cur
rent source of reversible polarity; and means in
terconnecting said output circuits with said feed—
back means whereby when said direct current
source is of one polarity one of said input wind
.
.
said developing means to said direct current
source.
12. A pair of magnetic ampli?ers each‘com
prising: a saturable core device having an alter
nating current winding and a direct current in- ‘
put winding, unilaterally conducting means con
ings ‘receives positive feed-back and the other
of said input windings receives negative feed
nected in series with said input winding, a ?rst
impedance, means for connecting said ?rst im
pedance in series with said alternating current
back and when said direct current source is of
the opposite polarity said one input winding re
transformer having primary and secondary wind
ceives negative feed-back and said other input
winding receives positive feed-back for causing
said input windings to receive unequal energiza
tion from said direct current source in accord
ance with the polarity thereof.
_
11. A pair of magnetic ampli?ers each com
prising: a saturable core device having an alter
winding across an alternating current source, a
ings, a second impedance connected in series with
said primary winding across said alternating cur
rent source, an output circuit arranged to’ be en
15 ergized responsive to ?ow of current in said a1
ternating current winding, and means for con
necting said secondary winding and said alter
nating current winding in series with each other
nating current winding and a direct current in
and with said output circuit; and means for con
put winding, a ?rst impedance, means for con
20 necting said series connected unilaterally con
ducting means and direct current winding of one
necting said ?rst impedance in series' with said
ampli?er and said series connected unilaterally
alternating current winding across an alternating
conducting means and direct current winding of
current source, a transformer having primary
the other ampli?er in parallel to a direct current
and secondary windings, a second impedance
connected in series with said primary winding 25 source of reversible polarity whereby said direct
current windings receive unequal energization
across said alternating current source, an output
from said direct current source in accordance
circuit~arranged to be energized responsive to
with the polarity thereof.
?ow ‘of current in said alternating current wind
ALAN S. FITZ GERALD.
ing, and means for connecting said secondary
winding and said alternating current winding in 30
REFERENCES CITED
series with each other and with said output cir
The
following
references are of record in the
cuit; and means for causing said input windings
?le of this patent:
to receive unequal energization from a direct cur
UNITED STATES PATENTS
rent source of reversible polarity comprising a
plurality of means for developing voltages of pre 35
Number
determined ?xed polarity and means for connect
ing one of said input windings in series with one
of said developing means to said direct current
source and means for connecting the other of
said input windings in series with another of
1,704,736
Name
Date
Geiger ___________ __ Mar. 12, 1929
1,914,220
Sorensen et al. ..__-_ June 13, 1933
2,277,849
2,338,423
~ 2,414,936
Fitzgerald _______ __ Mar. 31, 1942
Geyger ___________ __ Jan. 4, 1944
Edwards et al _____ __ Jan. 28, 1947