Sept. 29, 1953 F. H.

MCNTOSH 2,654,058
WIDE BAND TRANSFORMER
Filed Dec. 22, 1948 3. Sheets-Sheet l

12 10

INVENTOR.
FRANK H. McINTOSH
Sept. 29, 1953 F. H. MCINTOSH 2,654,058
WIDE BAND TRANSFORMER
Filed Dec. 22, 1948 3. Sheets-Sheet 2

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INVENTOR.
FRANK H. McN TOSH
Sept. 29, 1953 F. H. MCINTOSH 2,654,058
WIDE BAND TRANSFORMER
Filed Dec. 22, 1948
3. Sheets-Sheet 3

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INVENTOR.
BY FRANK H. McNTOSH
 Patented Sept. 29, 1953
2,654,058

UNITED STATES PATENT OFFICE

2,654,058
WDE BAND TRANSFORMER
Frank H. McIntosh, Chevy Chase, Md.
Application December 22, 1948, Serial No. 66,744
6 Claims. (C. 317-220)
This application was filed concurrently with 2
my application Serial #66,741, now Patent impedance. Such cores are adversely affected,
#2,477,074, issued July 26, 1949, and entitled in respect to the incremental inductance, by D. C.
magnetization. Hence the latter must be
“Wide Band Amplifier Coupling Circuits,' and avoided.
contains the same disclosure as the latter. The effect of leakage inductance on class B
The present invention relates generally to Wide push-pull amplifiers has been considered in the
band transformers for push-pull amplifiers, espe literature, and attention is directed particularly
cially of the bi-filar type. to an article by A. Pen-Tung Sah, in Proceed
The class B amplifier is a push-pull amplifier ings of the I. R. E. for November 1936. Sah
in which the tubes are biased approximately to points out particularly the deleterious effects of
cut-off. One of the tubes, in the normal system, leakage inductance between primary windings of
amplifies the positive half cycles of the signal the output transformer of such an amplifier,
voltage while the other amplifies the negative first, in causing a decreased output, as frequency
half cycles, the output transformer combining increases, and Second, in introducing finite time
the outputs of the two tubes, to reconstruct a constants into the circuit, thus causing transients
replica of the signal voltage. which distort the output wave as one of the tubes
The frequency limits of the conventional audio changes from a conducting condition to a block
or video amplifier depend largely upon the design ing condition, and vice-versa. The latter effect
of the output transformer, loss in amplification is the basis of great distortion at the higher audio
at low frequencies resulting from the low incre frequencies.
mental inductance of the transformer primary It is an object of the invention to provide novel
at low frequencies, and falling off at high fre push-pull transformers having negligible leak
quencies resulting from leakage inductance and age reactance,
the various distributed capacities of the trans It is a further object of the invention to provide
former. a push-pull wide band transformer of relatively
In order to obtain a good low frequency re simple and economical Construction, which elim
sponse the incremental primary inductance of inates leakage inductance between primary Wind
the transformer must be high relative to the ings of the transformer.
plate resistances of the tubes used. The primary It is another object of the invention to provide
winding of the transformer, then, should have 30 an improved push-pull transformer comprising
a large number of turns. At the same time the bi-filar primary Windings, and further to provide
resonant frequency of the transformer leakage push-pull audio amplifiers capable of employing
inductance and secondary capacitance must be transformers having bi-filar primary windings.
beyond the highest frequency desired to be It is, further, an object of the invention to
amplified, so that low leakage inductance and provide a push-pull transformer, having greater
shunt capacity is essential, if the frequency re coupling between the secondary winding and the
sponse of the transformer is to be extended. primary windings than is available in known
The above requirements are mutually conflict designs, thereby to improve the frequency re
ing, in various respects. The size of the core of sponse and to enlarge the band Width of Such
a transformer, i. e., the total iron utilized, is 40 transformers when employed in amplifiers.
limited by considerations of cost, Space and It is still another object of the invention to
weight requirements. This in turn fixes the total provide a push-pull transformer having radically
number of turns allotted to the primary and Sec reduced effective distributed capacity across the
ondary windings. Decreasing core size increas primary windings, and to provide a push-pull
ing total turns on the primary winding to retain 45 amplifier for effectively utilizing a transformer
high primary incremental inductance increases of this character.
leakage inductance and shunt capacity, which in It is a further object of the invention to pro
turn, reduces resonant frequency, and hence the vide a push-pull transformer of reduced dis
high frequency response of the transformer. tributed capacity and leakage inductance between
practice, leakage inductance is decreased by in 50 primary and secondary WindingS.
ter-leaving primary and secondary windings, but Briefly described, the various embodiments of
this increases distributed capacity and so tends the present invention hereinafter described in
to neutralize the benefits obtained. detail, and illustrated in the drawings, attain
As a further consideration, high permeability the objects of the invention by employing bi-flar
cores must be used, to increase primary Winding 55 primary windings in the output transformers to
 2,654,058
3 A.
reduce to a negligible value the leakage induct the band 20 to 20,000 cycles, the conversion effi
ance between these windings. The effect of Sub ciency of the amplifier tubes remaining above
stantially eliminating leakage inductance be 50% over the band, with an essentially flat re
tween primary windings is radically to reduce sponse over the band of 20 to 200,000 cycles.
transients during cross-over from one to another 5 Nevertheless, transformers constructed in accord
of the tubes of a push-pull amplifier, these tran ance With the present invention inherently cost
sients being particularly severe in class B Opera less to build than do transformers of the highest
tion. Leakage inductance between the primary quality fabricated in accordance with prior art
windings and the secondary likewise contributes principles, and require less space and weigh less
to these transient effects, but in reduced degree. than the latter.
Relating the primary windings in the manner Further, no transformers currently available
stated inherently enables reduction of leakage commercially or known to me are capable of at
inductance between primary windings and the taining the wide frequency response and low
secondary winding. wave form distortion attainable by the present
By proper arrangement and connection of the System, regardless of their cost, weight or Space.
primary windings in the transformer the equiva The above and still further objects, advantages
lent shunt capacity across the primary Windings, and features of the invention will become ap
due to the capacity between windings, which to parent upon consideration of the following de
gether with leakage reactance and the capacity tailed descriptions of various embodiments of
of the secondary winding determine falling off 20 the invention, especially when taken in conjunc
of response at the higher audio frequencies and tion. With the accompanying drawings, wherein:
the high frequency cut-off point of the amplifier, Figure 1 is a Schematic circuit diagram of an
may be similarly reduced, and the Windings may embodiment of the invention wherein is employed
be so related to the electronic tubes of the ainpli a pair of bi-filarly wound primary windings in
fier that but a single anode power Supply is re an output transformer having one of its coils con
quired, and that in certain of the embodiments nected in the cathode circuit of a vacuum tube of
conventional input circuits may be employed. a push-pull amplifier, and the remaining coil
The conventional mode of reducing leakage in connected in the anode circuit of the amplifier;
ductance consists of sectionalizing primary and Figure 2 is a Schematic circuit diagram illus
secondary windings and inter-leaving or inter a i trating a modification of the system illustrated in
spersing these. This type of construction is ex Figure 1 of the drawings, wherein the push-pull
pensive, and while it succeeds in reducing leakage amplifier utilizes Vacuum tubes having screen
inductance, results in increased capacities. The grids, each Screen grid being maintained at a
total capacity of the transformer windings may constant difference of potential with respect to
be reduced by avoiding the necessity for inter 3.5 its associated cathode during operation of the
leaving or pi-winding, in accordance With the amplifier;
present invention, in order to reduce leakage i Figure 3 is a Schematic circuit diagram of a
ductance. By avoiding the necessity for pi-Wind modification of the system of Figure 2, wherein
ing, or inter-leaving, furthermore, the transform controllable degeneration is provided in the am
er may be arranged more compactly, resulting In 40 plifier;
reduction of iron requirements, and in a simpli Figure 4 is a view, showing a transformer hav
fied, more economically fabricated core and ing bi-filarly Wound primary windings for use in
winding structure. push-pull amplifiers arranged in accordance with
In the conventional push-pull output trans the invention; and,
former for class B amplifiers the primary wind Figures 5, 6 and 7 represent variations of the
ings of the transformer are connected in Series bi-filarly wound transformer of Figure 4.
between the plates of the electronic tubes of the Referring now more particularly to the draw
amplifier. Accordingly, the primary windings ings and having reference particularly to Figure
being closely coupled, the total impedance of the 1 thereof, there is illustrated a push-pull ampli
primary windings is approximately four times the fier constructed in accordance with the princi
impedance of a single primary Winding. In act ples of the present invention and utilizing an out
cordance with certain embodiments of the pres: put transformer arranged in accordance with the
ent invention the primary windings of the out invention.
put transformer are not connected in series with The amplifier of Figure 1 is illustrated as em
each other between the amplifier tubes, but are 55 ploying a pair of triodes , 2 as amplifying elec
connected effectively in parallel. Thereby a re tronic devices, the triodes and 2 being provided
duction in anode terminal to anode terminal in respectively with grid leaks 3 and 4, which are
pedance by a factor of four, approximately, may connected between the control electrodes 5 and
be attained. Additionally, each coil, by reason 6 of the triodes and 2, respectively, the mid
of its bi-filar relation to another coil, is for the point of the grid leak resistors 3 and 4 being
same length of wire and length of coil of double grounded via a bias source 7. Driving potential
the number of layers, resulting in a further de is applied to the control electrodes 5 and 6 from
crease of shunt capacity. Reduction of anode to Sources Conventionally illustrated as generators
anode impedance of the Windings, is, therefore, 8, 9, which may be presumed to provide potentials
reflected in a corresponding decrease in anode to of opposite phases with respect to ground, and of
65
anode distributed capacity across the WindingS, Suitable relative magnitudes, the potentials pro
vided by the sources 8, 9 being applied to the
and therefore in a radical extension upwards Of control
the cut-off frequency of the amplifier, at its high electrodes 5, 6 via coupling condensers
end. Alternately, more turns may be employed 0 and respectively, the resistors 2 and 3
in the primary windings, and the resultant in 70 representing the internal resistances of sources
crease of shunt capacity, due to increase in the the bias source 7 may beThe
8 and 9, respectively.
such
bias established by
as to cause opera
number of turns, can be tolerated. tion of the triodes f and 2 to be either as class
Audio amplifiers constructed in accordance A, class AB or class B amplifiers, the significance
with the present invention, and tested for distor 75 of the classification being well understood in the
tion, have shown less than %% distortion over
 2,654,058
5 6
art, and defined by the Institute of Radio En to the triode 2, and vice-versa.
gineers in its official definitions. While the cir the direction of the voltages EAtexisting the same time,
cuits and structures of the present application both the windings 18 and 2 are always inacross iden
have wide utility in amplifiers operating in a C
cordance with any one of the above mentioned tical direction, despite the fact that current flow
classifications, the invention has primary appli 5 in the two windings is in opposite Sense because
cation to class B amplifiers, and will be described of theandfact that the windings conduct in alterna
accordingly as utilized in amplifiers of this class, tion are closely coupled.
If we assume that the triode 2 is cut off, and the
without intending thereby to limit the Scope of triode conducting, for example, the winding 8
the invention. For the purpose stated, the bias 10 induces
source T will be established to have a value Such with its inownthevoltage,winding 2 a voltage congruent
and in the same sense in
as to cut off the plate current of the triodes the two windings, the voltage in winding 2, how
and 2, in the absence of signal voltage applied ever, being incapable of causing current flow in
to the grids thereof.
The input circuits of the triodes and 2 will, 6 is now2 because
triode the input voltage applied to grid
accordingly, be seen to be completely convent 5 tude negative in phase and of sufficient ampli
tional and to form essentially no part of the anodewith respect to the voltage applied to the
22 of triode 2 by winding 2 f, to prevent
present invention.
A source of anode voltage 4 is provided, cont such current flow. Precisely the same argument
may be presented when triode 2 is conducting and
ventionally illustrated as a battery to simplify 20 triode cut off.
the drawings. The negative terminal of Source
is is grounded via the lead 5, and the posi Furthermore, the terminals 28 and 29 of the
tive terminal of source 4 is connected directly primary windings 8 and 2i are directly con
nected together via the potential source 4, which
via the lead 6 to the anode 7 of the triode f, may be assumed to have zero impedance, and the
the primary winding 8 of output transformer T
being connected in the cathode lead of the triode total number of turns contained in the Windings
f8 and 2 and are precisely equal. Accordingly,
I, intermediate the cathode 9 thereof and the no
negative terminal of the potential source 14. twoA-C. potential difference exists between any
adjacent points of the windings 8 and 2,
The cathode 20 of the triode 2 is connected di
rectly to ground and a further primary winding So that but slight or zero capacitive currents flow
30
between adjacent turns of the primary Windings
2 of the output transformer T is connected be
tween the positive terminal of the potential source 8 and 2. Such currents as do flow tend to
4 and the anode 22 of the triode 2. maintain the potentials of adjacent points of the
The primary windings 8 and 2 are wound two primary windings 8 and 2f identical, and
accordingly
in bi-flar manner, or equivalently, as indicated 35 of contribute to the proper functioning
the System.
in the schematic circuit diagram, the Wires form
ing one of the windings being immediately adja A condenser C may, if desired, be connected di
cent the wires forming the other of the Windings rectly from cathode 9 to anode 22 without al
so that substantially Zero leakage inductance tering the operation of the system essentially, but
exists as between the windings 8 and 2. to assure the equi-potential relation between ad
If it be assumed that a sine Wave of potential 40 jacent turns, particularly at the higher fre
is applied to the control electrodes 5, 6 by the quencies, where Some leakage reactance might
sources 8, 9, the positive half of the sine Wave de conceivably be present due to imperfections of
riving from source 8 effecting current transfer the winding spacings.
through the triode I, and the positive half of the 45 It will be noted, upon close analysis, that, the
sine wave deriving from source 9 effecting cur triode being cathode loaded and the triode 2
rent transfer through the triode 2, it will be ap anode loaded, the former is subject to degenera
parent that while the positive half of the first tion and the latter is not so subject. The gains
mentioned sine wave is applied to the control of the triodes and 2 are not equal, for that rea
electrode 5 that the triode 2 is cut off and that 50 Son, and the input signals must be compensated
current flow through the primary winding 8 accordingly. This feature of the system of Fig
takes place in the direction of the arrow 23. On lure 1 detracts from its utility, in some degree.
the other hand, while the positive half of the The circuit illustrated in Figure 2 of the draw
second mentioned sine wave is applied to the ings provides a solution to the problem of at
control electrode 6 of the triode 2, the triode 55 taining maximum power conversion from pen
is cut off and current flow through the primary tode and tetrode tubes in cathode loaded push
winding 2 takes place in the direction of the pull amplifier circuits, arranged in accordance
dotted arrow 24. Accordingly, with respect to With the present invention, the solution con
the flux produced in the core 25 of the trans Sisting in Connecting the screen grid 42 of one
former T, current flow in the windings 8 and 60 pentode 40 directly to the anode 43 of the other
2 is in opposite directions, so that an alternating pentode 4, and the screen grid 44 of the other
magnetic flux is set up in the core 25, and an pentode 4 directly to the anode 45 of the first
alternating voltage induced in the Secondary pentode 40. The connection of the screen grid
winding 26 of the transformer T, for applica 42 to the anode 43 implies connection of the
tion to the load circuit conventionally illustrated 65 Screen grid 42 to the terminal 46 of the output
as a resistance 2. transformer winding 30, which is maintained at
By virtue of the close coupling existing between the Same A. C. potential as is the point 37 of the
the primary windings 8 and 2, the close cou Winding 35. Since the terminal 37 is always at
pling being brought about by the manner of the cathode potential of the pentode 40, likewise
winding the primary windings 8 and 2, Sub 70 the terminal 46 of the winding 30 is maintained
stantially no leakage reactance will exist between at the same A. C. potential as is the cathode of
these primary windings, and, accordingly, as ex the pentode 40, the D. C. potential existing be
plained in the article by Sah, cited hereinbefore, tween the two points being, however, that pro
no transient effects will exist during change over Vided by the potential source 4. Accordingly, as
of current carrying function from the triode 75 the cathode of the pentode 40 varies in potential,
due to the presence in the cathode circuit of the
 2,654,058
8
current carrying winding 36, the potential of the rondary winding, Figure 5 illustrating a variant
screen grid 42 varies in precisely similar man “of the system of Figure 4 employing superposed
ner. The difference in potential is thus main coils in place of bi-filarly wound coils, the trans
tained constant, thereby maintaining maximum former of Figure 5 being in many respects equiv
spower conversion from the pentode. alent to the transformer of Figure 4, when the
winidings are properly connected in a push-pull
A precisely similar explanation may be pro :amplifier arranged in accordance with the inven
vided in connection with the pentode 4, this ex
planation, however, being sufficiently obvious. tion. Figures 6 and 7 illustrate variants of the
transformer of Figure 4 wherein separate layers
. . It Will be further realized that while I hiave
'disclosed tubes 40 and 4 as pentodes, that pre ) 'of a single coil are incorporated by suitable in
'cisely the same principles and mode of operation terlayer connections in different primary wind
-and circuit connections may be employed in con ings of a push-pull transformer, providing a fur
ther approximate equivalent for a bi-filarly
junction with the use of tetrodes, including beam
power tubes, in the 'circuit of Figure 2. wound transformer.
Reference is now made to Figure 3 of the Referring now more specifically to Figure 4
drawings, which illustrates basically a system of of the drawings, there is illustrated a core foo of
the same character as that illustrated in Figure2 conventional structure having wound thereon a
of the drawings, there being added to the latter, coil f of formed of a plurality of bi-filarly wound
layers O2, the winding commencing at poiht lo3
however, controllable degenerative feed-back, 2) and terminating at point (04. Leads 105, F06 are
Still further to reduce the distortion of the ania
splifier, or in the alternative to necessitate reduced brought out from the commencement point E03
driving signal, as compared with the 'embodi of the bi-filar winding, to which may be con
ments of Figure 2. Jin the system of Figure 3 of nected B+ and B-terminals of a voltage supply,
the drawings, controllable degenerative feed when the transformer is connected in an ampli
back is derived by connecting across the primary 2:2 5 fier circuit. Similarly from the end of the wind
ing, at point (C4, are brought out two terminals
Windings 35 and 36, which are connected in the
cathode leads of the triodes and 2, a resistor the f07, fo8, intended for connection, respectively, to
50, the latter then having developed across itself plate or anode Pf of one amplifier tube of a
'a voltage which is a replica of the output voltage push-pull amplifier, and the cathode C2 of the
-available at the output of the transformer T. A : remaining tube.
pair of variable taps 5 and 52 are provided, taps A duplicate coil flois wound on the same core
5- and 52 being located generally at points equi beside the coil (07, having terminals if I and 12
“distantly located with respect to cathodes 20 and for connection respectively to B+ and B-ter
f9, respectively. Accordingly, by varying the minals of the voltage supply, and terminals 13,
positions of the taps 5 and 52 the total feed- 3 ) n
fit for connection respectively to the cathode
back voltage to each of triodes and 2 may be Ct of the one tube and the anode P2 of the re
varied. The voltage deriving from the tap 5 is maining tube.
applied to contol electrode 6, via a coupling con It will be noted that the respective windings
denser 53, which is connected to one terminal of are wound in opposite winding senses with re
the secondary winding 56 of an input transformer ity spect to the core foo, for reasons explained here
S, which is supplied with exciting voltage via a inabove, and briefly because the coils O and O
are intended to produce flux in push-pull, or al
primary Wilding 57 excited from the source of
signal voltage A in conventional fashion. The ternately in opposite directions in the core too.
remaining terminal of Secondary winding 56 is Secondary windings 5, 16 are superposed on
the primary coils FOf and 10, respectively, and
connected to the control electrode 6 of the triode 3. are shown connected in series by a lead i? 7, it
2. While the control electrode 6 is being raised in being tinderstood
potential and the tube 2 is conducting, the po ‘equally feasible. that parallel connection is
tential of the tap 5 decreases in potential due to
In the broadly or approximately equivalent
current flow in resistor 59 in the direction of the system of Figure 5, bi-filar windings are dis
arrow I, the cathode 20 of the triode 2 being then : pensed with,
at higher potential than is the cathode 9 of the vided, numbered and four primary windings are pro
triode 1. In a similar manner, the tap 52 intro 20, 21, 22 and 23. The
duces a degenerative voltage into the grid of the superposed windings f20 and 12 are wound in
nutually identical sense, and the superposed
triode via a coupling condenser 53a which is
connected in series with one terminal of the sec 5 windings 22 and 123 in identical sense, the latter
ondary winding 58 of the transformer S, the other two oppositely to the first mentioned two wind
terminal of winding 58 being connected to the ings, and the winding pairs are arranged adja
cently Gh the core. The initial point 24 of
control electrode 5 of the triode I. Grid leaks for
triodes and 2 are provided by resistors 54 and winding 20 may be connected to terminal B
and the terminating point 25 of winding 2 to
59, respectively connected in series with bias
source 55. terminal B+, of a plate voltage supply source,
It will be clear, then, that, by moving tap 51 by appropriate terminals provided, and the ter
to cathode 9, and tap 52 to cathade 29, zero de minal points 24 and 25 being thus joined by a
generation will beintroduced into the system, and path of negligible A-C. impedance remain at
that degenerative voltages having values as great 65 identical A-C. potential. The terminal point 26
as twice those normally available in the system of of winding 20 and the initial point 21 of wind
Figure 2 may be made available by establishing ing 12t are arranged to be in close juxtaposition,
tap 5 at cathode 9, and tap 52 at 'cathode 20. and are joined by a condenser Kl, which serves to
Reference is accordingly made to Figures 4 to haintain the points 26 and 27 at identical A-C.
7 inclusive, of the drawings, wherein is illus potentials.
trated a plurality of different transformer wind The terminal point 26 may be connected to
ing constructions which may be employed in the Cathode C2 and the terminal 27 to anode P.
circuits of Figures 2, 3. Figure 4 illustrating a The coil 22 may be similarly arranged, termi
transformer having four primary windings, bi Ital 28 being connected to B-, terminal 29 of
filarly wound, and associated with a common sec 75 'Coil f23 to B+, and terminals A30 and 3 joined
 2,654,058
9 10
by a condenser K2, so that the terminals of pair are connected in series by leads 62 to provide
28, 29 and the terminals of pair 30, 3 are
at identical A-C. potentials. Terminal 30 may
the other winding. The initial points of the first
and second layers may be connected respectively
be connected to cathode C and terminal 3 to to the B-- and B-terminals of a voltage Supply,
anode P2, of the tubes of the amplifier employing and the two outermost Windings (the eleventh
the transformer. The secondary winding 32 and twelfth layers of a twelve layer Winding, for
may be arranged as in the embodiment of Figure example), connected to the cathode, C2, of one
4 of the drawings. vacuum tube and the anode, Pt, of a further vac
It will be realized that leakage inductance, in uum tube of a push-pull amplifier arranged in
the case of the embodiment of my invention ill 0. accordance with the invention. The latter two
lustrated in Figure 5 will be greater than in the terminals may be connected across a condenser
case of the embodiment of Figure 4. However, K to assure that the same A-C. potential exists
the transformer of Figure 5 may conceivably be at these terminals, as in the transformer arrange
more economically constructed than the trans inents of Figures 5 and 6, inclusive. The upper
former of Figure 4, and may prove desirable for 5 windings may be duplicated to provide two pairs
that reason. of bi-filarly wound equivalents.
In Figure 6 of the drawings is illustrated a it will further be realized, while the transform
further modification of the system of Figure 4, ers illustrated in Figures 4, 6 and 7 approach
wherein the effect of a bi-filar coil is attained relatively closely to the ideal, or bi-filarly wound
by winding the respective primary Windings transformer, that the gmbodiment of Figure 5
which are desired to be unity coupled, in Suc is at best a very rough approximation, and, while
cessive layers, and joining the layers thereafter operative, operates but imperfectly in circuits ar
by means of suitable leads. Having particular ranged in accordance with the invention, and is
reference to a transformer suitable for use in not recommended except in cases where other
the amplifier system of Figure 2, for example, the considerations than excellence of performance
winding 29 may comprise the winding layers 4, are primary.
42, 43, 44, 45, 46, etc., and the winding 30 It will further be realized that further variants
the alternate layers 47, 48, 49, 50, 5 . . . . of the transformers illustrated in Figures 4, 6
The terminal point of layer 4t may be connected and 7 may be resorted to without departing from
to B- and its other end point joined by lead 50 3 the true scope and spirit of the invention, which
to an adjacent end point of layer 42, the layers requires the provision of unity coupled trans
4 and 42 being wound in the same direction formers, for best performance, and which may
and current in each turn of both layers 4 and employ any type of unity coupled transformers
42 flowing in the same sense, to produce mutu having the requisite windings, and which are
ally additive flux in the core. The process of known or which may become known to the att.
layer interconnection is continued to the end Of While I have described various modifications
the winding, the winding layers 4t, 42, 43 . . . of output transformers having bi-filarly wound
being thus connected in series. The alternate primary windings, further modifications may be
layers, 47, 48, 49 . . . are likewise connected devised, and re-arrangements and modifications
in mutual series relation by leads 6, and a Sec 40 of the Systems illustrated and described, resorted
ondary winding 63 may be superposed on the to, without departing from the true spirit and
primary windings, in conventional fashion. The Scope of the inventions, as defined in the ap
terminal points of the outermost pair of adjacent pended claims.
winding layers may then be brought out to anode What I claim and desire to secure by Letters
P and cathode C2, respectively. Patent of the United States is:
A similar pair of primary windings 64 and 1. A wide band audio transformer, compris
65 may be provided on the core, adjacent to the ing, a first primary winding, a second primary
primary windings 29 and 30, for connection to winding, a third primary winding, a fourth pri
the anode P2 and the cathode C, and with the mary winding, a core of magnetic material, said
windings 29 and 30 associated a further Second- it first primary winding comprising a first strand
ary winding 64, connected in series with Sec of electrically conductive material wound on said
ondary winding 63, it being understood that par core in a first winding sense, said Second pri
allel connection is equally feasible. mary winding comprising a strand of electrically
It will be realized, since the windings are ad Conductive material Wound On Said core in said
jacent in alternate layers, and since the starting is first winding sense and in continuous juxtaposi
points of initial layers 4 and 47 are adja tion to said first strand, said third primary wind
cent and inter-connected by a path of low in ing comprising a third strand of electrically con
pedance provided by the voltage source B-- and ductive material Wound on said core in a sense
B-, that the potentials of adjacent turns of opposite to Said first winding sense, said fourth
each pair of layers is ideally at identical A.-C. primary Winding comprising a fourth Strand of
potential. To compensate for any departures electrically conductive material wound on said
from ideal conditions, brought about by Winding core in continuous juxtaposition to Said third
irregularities and the like, I may inter-connect Strand, and at least one secondary winding
the ends of the windings by means of a large Wound on said core of magnetic material.
condenser K, which establishes the ends of the 2. An audio transformer for transferring a
windings at identical A.-C. potential. band of signals over the spectrum 20-20,000
Figure 7 illustrates a winding sequence which cycles with less than 1% distortion, comprising,
approaches that of the sequence provided in the a core of magnetic material, a first pair of bi
embodiment of Figure 6 of the drawings, the filarly wound windings linking with said core
winding being laid in successive layers, 70 which about one portion thereof, and wound in one
are left mutually unconnected when the coil is winding sense, a second pair of bi-filarly wound
wound. The first, fourth, fifth, eighth, ninth, windings linking with said core about a further
twelfth . . , layers are connected in series by portion thereof, and Wound in an opposite Sense
leads 6 to provide one winding; the second, and a secondary winding linking said core.
third, sixth, seventh, tenth, eleventh . . . layers 75 3. A wide band audio or video transformer,
 2,654,058
12
comprising, a magnetic core; a first center tapped material. Wouad. On said core in a sense. Opposite
primary winding, having oppositely wound halves, to said first wirading sense, said fourth, primary.
a second center-tapped primary winding having. Winding comprising a fourth Strand of electri
oppositely wound halves and bi-filarly related to: cally condugtive material. Wound on said core in:
said: first winding, and a secondary Winding continuous juxtaposition to said third strand,
coupled simultaneously to all, said primary Wind Said third and fourth Strands, mutually, insulated
ingS. OVer their entire, lengths, and Wound in an even
-4. A wide band audio? or video transformer, plurality of superposed helices, and at least, One.
comprising, a first primary coil having two Series: SeeOFadairy Winding. Wound on said core of mag
connected first primary: windings, each continu O netic material.
ously wound in a different winding sense, a Sec 6. The combination, in accordance with claim:
and primary coil having two series: connected 5. Wherein the terminations of said, first- and sec:
second primary windings each bi-filarly related Oad stralads, respectively, and, said third, and
to, one of said: first, primary. Windings, means for fourth Strands, respectively, travel paths.of idens
connecting a source of D.-C. voltage-between the 5. tical diameter in each of Said plurality of helices.
junction of said first primary windings and the
junction of said Second primary WindingS. FRANK H. McINIOSH.
5, A. Wide band audio transformer, compris
ing a first primary winding, a second primary. References. Cited in the file of this patent
winding, a third primary winding, a fourth: pric UNIEEE). SATES, RATENS
mary, winding, a core of magnetic material, Said Nirber Name Date.
first primary winding comprising a first, strand, 1,561,204 Beers ------------- Nov. 10, 1925:
of electrically conductive-material. Wound. On Said. 1,576,280; Horelick ----------- Mar: 9; 1926
core: in a first winding sense, said: Second pri
mary winding comprising: a strand of electrically. 25 1,66,200' Shackelton -------- Feb. 1, 1927
conductive material Wound on Said core- in Said 1781,308 WoS ---------------. Nov. 1, 1930:
first winding sease, and in continuous juxtaposi 1,809,839 Field ------------- June 16, 1931
tion...to said first strand; Said juxtapositioned first, 2,132,875 MyerS ------------- Gett. 11, 1938
and second strands, mutually insulated Over their FOREIGN. PATENTS .
entire; lengths, and wound in an even. plurality 30, Ninher Country 9ate.
of Sugerposed helices, said third winding. Con-, 171,836. Great Britain. ... Deg;, 1, 1921
prising a third strand of electrically, conductive