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Publication numberUS1969657 A
Publication typeGrant
Publication dateAug 7, 1934
Filing dateOct 29, 1930
Priority dateOct 29, 1930
Publication numberUS 1969657 A, US 1969657A, US-A-1969657, US1969657 A, US1969657A
InventorsMccaa David G
Original AssigneeMccaa David G
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of and means for reducing electrical disturbances
US 1969657 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

D. G. M CAA Aug. 7, 1934.

METHOD AND MEANS FOR REDUCING ELECTRICAL DISTURBANCES 2Sheets-Sheet 1 Filed Oct. 29, 1950 p in? a yz Aug. 7, I D. G MccAA 1,969,657

METHOD OF AND MEANS FOR REDUCING FILECTRICAL DISTURBANCES Filed Oct. 29, 1950 2 Sheets-Sheet 2 Patented Aug. 7, 1934 PATENT OFFICE METHOD OF AND MEANS FOR REDUCING ELECTRICAL DISTURBANCES David G. McCaa, Philadelphia, Pa.

Application October 29,

18 Claims.

The present invention relates to improvements in means for reducing and limiting interfering pulsations in electrical circuits through which electrical energy is being transmitted in useful form and especially to apparatus and methods adapted to reduce the influence of atmospheric devices originating externally of the device and is a continuation'in part of the invention disclosed in my co-pending application, Serial No.

320,849,.filed Nov. 21, 1928, which, in turn, is a division of my application, Serial No. 74,087, filed Dec. 8, 1925, upon which Patent No. 1,814,051 dated July 14, 1931 has issued. This application and co-pending application, Serial No. 492,054

.15 filed October 29, 1930, relate to the same generic invention, each being intended to cover diiferent modifications thereof.

As is well known, when electrical disturbances are in evidence duringradio-reception, they take 20 the form of audible noises which often completely submerge all other reproduced sounds. The origin of such disturbances cannot be readily controlled nor their arrival at the antenna prevented. Hence the place where their effects may be decreased is confined to thevicinity of the receiving system itself. To reduce or substantially eliminate the effects of the oscillations, by which such disturbances are produced, requires that such oscillations be so far as possible nullified and one method of accomplishing this purpose is to reduce the ratio of the energy due to disturbing oscillations to the'energy due to the desired or signal oscillations. It is, therefore, the object of the present invention to provide a method and apparatus so designed that the effects of electrical disturbances can be controlled and largely reduced without unduly affecting the quality of reception of desired signals, thus permitting the reception of signals with great deal more clarity and substantially as great intensity as when no disturbances are present.

Another object is to provide an improved method and device for differentiating in electrical circuits between impulses of electrical energy of different amplitudes, the higher amplitude waves being damped as, for example, atmospheric static or other similar electriddisturbances and the lower amplitude wave being the desired signal wave. l

. A further object of the invention is to provide a method and apparatus that will enable the electrical disturbances to be divided into components and so controlled that the divided com ponents oppose each other in such a ratio that the components of the low amplitude: signal waves 1930, Serial No. 492,052

will oppose each other to only a slight extent while the components of the high amplitude impulse waves will oppose each other to such an extent as to completely neutralize each other when the amplitude of said high impulse waves is a maxi- 59 mum.

Another object of the invention is to provide a method and apparatus by which the effects of electrical disturbances may be substantially reduced to a point where they are no longer troublesome and which can be operated in connection with an ordinary receiving system in either radio or telephone line communication. The apparatus in this respect, including appliances, may be disposed either between the receiving system and the input thereto or connected into the circuit of the receiving system between the output of the system and the sound reproducing device or it may be applied directly to the sound reproducing device itself. l

Other objects and advantages of the invention will appear more fully hereinafter from the following detailed description taken together with the accompanying drawings, in which:

Fig. 1 is a schematic wiring diagram illustrating the basic arrangement for carrying out my invention;

Fig. 2 is a diagram illustrating a specific embodiment for carrying out my invention;

Fig. 3 is a graphic representation of the operation of the system disclosed in Fig. 2;

Fig. 4 is a modified embodiment of the syste of my invention;

Fig. 5 illustrates another embodiment in which the principle of the invention is applied directly to an electrodynamic sound reproducer; and

Fig. 6 is a detail View of an electrodynamic sound reproducer showing the relation of the energizing coils with respect to the acoustic diaphragm. V

Referring to Fig. 1, there is shown a system comprising two paths which present to currents flowing therethrough impedances Z1 and Z2, respectively. Four transformers P, P, P and P couple the two paths to common input and out- 100 put circuitsthe secondary windings oftransformers P1 and P1 being connected in opposition as indicated. A source of wave energy G is connected in series with the primary windings of transformers P and P. The output terminals X 105 and Y may be connected to any circuit or translating device. Y

The impedance devices Z1. and Z2 each may have anyone of threepossible characteristics. They may favor the undesirable high amplitude waves 110 by presenting much less impedance to such waves than to low amplitude signal waves. They may favor the low amplitude signal waves by presenting much less impedance to them than the high amplitude waves, or they may have a straight line characteristic favoring neither high nor low amplitude waves, the current merely being proportional to the applied voltage. This will be more clear as the description proceeds.

Referring to Fig. 2, the terminals 1 and 2 may be connected to antenna and ground, respectively, or to any other source of signal energy. A transformer 5 has its primary 6 connected to the terminals 1 and 2 and the secondary 7 is connected to two paths comprising, in one case resistance R and primary 9 of transformer 8 and, in the other case, two groups, A and B, of rectifying devices 13 and 14 and another primary 10 of transformer 8. The rectifier elements 13 of group A are arranged in opposed relation to the rectifier elements 14 of group B and, in this instance, are provided for use as asymmetrical impedance devices rather than as rectifiers. The primaries 9 and 10 of the transformer 8 are arranged in opposed relation so that the energy in the path including the resistance R opposes the energy in the path including the rectifying elements 13 and 14. The secondary 11 of the transformer 8 is connected to the output terminals 3 and 4. It will be noted that when the primary 6 becomes energized, the corresppnding voltages are produced across the secondary '1 and for one-half cycle of the incoming wave, for example, when the upper terminal of the secondary 7 is positive, current will flow through the junction point 7a where it divides, part of it going through resistance R, primary 9 and back to the other terminal of the secondary '7. The other portion of the current will flow from the junction 7a through the rectifying elements 13, through primary 10 in opposed relation to the current in primary 9 and back to the transformer secondary 7. In the second half cycle of the wave, when the upper terminal of the secondary 7 is negative, current fiows through the resistance R and primary 9 as before except in the reverse direction and the other portion of the circuit now flows through primary 10 in opposition to the current in primary 9, through the rectifying elements 14 and back to the secondary '7. In this way, both halves of the incoming waves are acted upon.

Referring to Fig. 3, which graphically illustrates the relation of the currents in the paths of primaries 9 and 10 of Fig. 2, the curve IA represents the current flowing through the rectifier elements 13 for various values of voltage E. The curve In is symmetrical with the curve IA and indicates the current passing through the rectifier elements 14 and is illustrated in Fig. 3 below the voltage axis. The curve In, on the other hand, is a straight line showing the linear variation of current when the voltage of the current is opposite to the currents in either of the rectifiers, because of the opposed relation of the windings 9 and 10. The path through the rectifiers then favors the high amplitude waves while the path through the resistance is impartial.

It will be noted that parts of the curves IA and In extend beyond the origin in a negative direction from the origin and the resultant current is illustrated by the curve IA+B.

To make clear the operation of the circuit of Fig. 2, the signal waves have been shown as having a value s as compared to the high impulse waves, such as atmospheric static, having a value c. It will be noted that when the high impulse Waves have a value equal to c, the current in the path of the rectifying elements is exactly equal but opposite to the current in the path of the resistor R, as indicated by the points a and a respectively, the resultant output in secondary 11 being zero. If the voltage of the high impulse wave is half the value as indicated by the point g, the resultant output in transformer 11 will be reduced to 50% of the input, as illustrated by the point h on the curve IA+B-IR. For the low amplitude signal waves, the voltage of which has been assumed to be of a value c, the resultant output of secondary 11 is approximately of the input as illustrated by the point f on the curve IA+B IR. It will, therefore, be noted that the high impulse waves will be substantially reduced or practically neutralized while the low amplitude signal waves are permitted to pass through to the extent of approximately 80% or more. The same results are, of course, obtained on both halves of the wave, as illustrated in the left portion of the diagram of Fig. 3.

The rectifying elements 13 and 14 may be carborundum crystals provided with proper bias or may be rectifiers of the dry-contact or metallicoxide type. The characteristic curves IA and In may be varied by varying the contact pressure between the rectifier elements or varying the number of units for each of the groups A and B or varying the area of contact between each pair of members of the rectifier elements. The resistor R is made adjustable in order that the point a on the curve In may be adjusted to correspond to the point a on the curve IA+B for various values of the input voltage. By adjusting the rectifier elements and the resistor R, the characteristics of each may be so modified that the reverse action may take place, that is, the low amplitude waves may be made to substantially neutralize each other while the high amplitude impulses may be permitted to pass through the system. Furthermore the system illustrated in Fig. 2 may be operated either with terminals 1 and 2 as the input and terminals 3 and 4 as the output or vice versa. The same results will be obtained in either case.

Fig. 4 illustrates a modification in which the input terminals 27 and 28 are connected to a pair of primaries 31 and 32 connected in series opposed relation on the cores 33 and 34, respectively. In this instance, a secondary 35 is wound on the same core 33 with primary 31 and the secondary 36 is wound on the same core 34.- with the primary 32.

The secondary 35 provides one path through a circuit including the primary 31 which is wound on core 33 and secondary 36 provides a second path through a circuit including the primary 32' which is wound on a core 34. The secondaries 35 and 36' are wound on the same cores with primaries 31 and 32' respectively and in series opposed relation to each other as indicated by the arrows. They constitute the output circuit of the system and are connected to the output terminals 29 and 30. Two groups of rectifiers A and B are connected in shunt relation with secondary 35 and primary 31 while two similar groups A and B are connected in series with secondary 36 and primary 32. The circuit of secondary 35 with groups A and B inshunt therewith ofiers a higher impedance to high ampli-- tude impulses than the circuit of secondary 36 which is in series with groups A and B. In

order that the relative gain of the output transr le formers may be varied, windings 32" and 36 are arranged so that their coupling may be varied,

as indicated by the arrow. The reason for this will appear presently. Obviously the gain of the output transformers may be varied in other ways, such as by means of tapped windings, potentiometers across the windings, etc.

Ifwe assume that the path through rectifiers A and B favors signal currents over high amplitude currents in the ratio 2 to I, that the path through rectifiers A and B favors high amplitude currents over signal currents in theratio 2 to 1, and that transformer 3l'-35 has a stepup ratio of 2 to 1, thecoupling of transformer 32'36 necessary to balance out the high amplitude currents may be readily determined. For example, if the incoming wave comprises 10 units of signal waves and 40 units of high impulse waves, then assuming that 5 units of signal waves and units of high impulse waves appear in primary 31, 10 units and units respectively will appear in secondary 35. Now if 2%; and 20 units respectively of signal and high amplitudewaves appear in primary 32', then the 'cou c pling of windings 3234' must be such that a ratio of 1 to 1 is obtained, thus balancing out the high amplitude waves and giving a resultant of 7 units of signal waves in the output circuit.

In Fig. 5 is shown a modification in which a primary 39 is connected to the input terminals 37 and 38 and is wound on a'core 40 with a secondary 41 mounted on the same core. The output of the secondary is divided into-two paths in the samemanner as in Fig. 1 but, in this instance,

:5 the circuit is arranged to actuate an electrodynamic loud speaker having movable coils M1 and M2 which are adapted to actuate an acoustic diaphragm and are arranged in opposed relation similarly as the primaries 9 and 10 in Fig. l and are connected so that the coil M1 is in the path of resistor Rwhile the coil M2 is in the path of. the rectifier groups A and B. The sound reproducer is provided with'the usual field coil 46 energized by-a source of direct-current energy 47 and wound on the pole piece 43 of a magnet 42 which is provided with additional pole pieces 44 and 45 so that the like poles thereof are opposite each other and the armature coils M1 and M2 are located therebetween.

Fig. 6 illustrates more clearly the arrangement of the coils Ml and M2 to cooperate with the acoustic diaphragm 48 and shows schematically a section taken through the magnet 42 and through the armature coils M1, M2 and through the field coil46. In this instance, when the high impulse waves are of sufiicient value to cause equal currents to flow through coils M1 and M2, they will be substantially neutralized and, therefore, produce no action on the diaphragm 48, whereas the low amplitude signal waves will affect the diaphragm in proportion to their amplitudes as indicated on the curve IA+BIR.

It will be noted that the systems of the present applications differentiate from the systems dis- E closed in my c-o-pending application Serial No.

320,849 hereinbefore mentioned in that the impedance in the path provided to discriminate against the low amplitude waves is of a finite value for waves of all amplitudes which may normally be introduced into the path while the impedance of the corresponding path in the systems of the co-pending application becomes infinite for certain amplitudes.

While I have shown several modifications of my invention for purposes of illustration and description and for explaining the operating principles, other changes and modifications therein may be apparent to those skiled in the art and I, therefore, desire to be limited only by the scope of the appended claims.

I claim:

1. In a device for discriminating between electrical waves of a given amplitude and impulse waves of a different amplitude, two electrical paths operative with respect to the source of said waves, an impedance device associated with each of said paths, the impedance of the device of one of said paths adapted to vary in relation to the energy in said patir while the impedance of the other device remains constant, the impedance of both of said devices being of finite values to all Waves derived from said source, and a system assoeiatedwith both paths for combining the energy from said paths.

2. In a device for discriminating between electrical waves of a given amplitude and impulse waves of a diiierent amplitude, two electrical paths operative with respect to the source of said waves, an impedance device in each of said paths, the impedance of the device of "one of said paths varying in relation to the amount of energy associated with its path, while the impedance of the device of the other path remains substantially constant, the impedance of both of said devices being of finite values to all waves derived from said source, and a system associated with both paths for combining the waves of said paths in opposed relation.

3. In a device for discriminating between electrical waves of a given amplitude and impulse waves of a different amplitude, two electrical paths operative with respect to the source of said waves, one of which has associated therewith a symmetrical impedance device, the other of which has associated therewith a pair of asymmetrical impedance devices in reverse relation, and a system associated with both paths for combining the energy of said paths.

4. In a device for discriminating between elec trical waves of a given amplitude and impulse waves of a difierent amplitude, two electrical paths operative with respect to the source of said waves, one of which has associated therewith a symmetrical impedance device, the' other of which includes a group of asymmetrical impedance devices, and a system associated with both for combining the energy of said paths in opposed relation.

5. In a device for discriminating between electrical waves of a given amplitude and impulse waves of a diiierent amplitude two electrical paths operative with respect to the source of said waves, one of which includes a symmetrical impedance device, the other of which includes a pair of groups of asymmetrical impedance devices arranged so that one group operates on one-half cycle of said waves and the other group on the other half cycle of said waves, and a system associated with both paths for combining the energy of said paths in opposed relation.

6. In a device for discriminating between electrical waves of a given amplitude and impulse waves of a different amplitude, two electrical paths operative with respect to the source of said waves, one of said paths including a resistor, the other of said paths including two groups of rectifying devices arranged to operate on both halves of said waves, and an output circuit inductively related to both paths for combining the energy from said paths.

7. In a device for discriminating between electrical waves of a given amplitude and impulse waves of a different amplitude, two electrical paths operative with respect to the source of said waves, one of said paths including a resistor and a primary winding of a transformer, the other of said paths including two groups of rectifying elements arranged to operate on both halves of said waves and a second primary of said transformer, said primaries being arranged so that the energy from said paths will be combined in the secondary of said transformer.

8. In a device for discriminating between elec trical waves of a given amplitude and impulse waves of a different amplitude, two electrical paths operative with respect to the source of said waves, one of said paths including a resistor and a primary winding of a transformer, the other of said paths including two groups of rectifying elements arranged to operate on both halves of said waves and a mcond primary of said transformer, said primaries being arranged so that the energy from said paths will be combined in opposed relation in the secondary of said transformer.

9. In a device for discriminating between electrical waves of different amplitudes, two electrical paths operative with respect to the source of said waves, one of said paths including an impedance system associated therewith, the ratio of output to input of one path increasing as the input Wave amplitude increases, and the ratio of output to input of the other path being at least as low for high amplitude input waves as for low amplitude input waves.

10. In a device for discriminating between electrical waves of diiierent amplitudes, two electrical paths operative with respect to the source of said waves, one of said paths including an impedance system associated therewith, the ratio of output to input of one path increasing as the input wave amplitude increases, the ratio of output to input of the other path being at least as low for high amplitude input waves as for low amplitude input waves, and a system associated with said paths for combining the energy from said paths.

11. In a device for discriminating between electrical waves of difierent amplitudes, two electrical paths operative with respect to the source of said waves, each of said paths including an impedance system associated therewith, the ratio of output to input of one path decreasing and of the other path increasing as the input wave amplitude increases.

12. In a device for discriminating between electrical waves of different amplitudes, two electrical paths operative with respect to the source of said waves, each of said paths including an impedance system associated therewith, the ratio of output to input of one path decreasing and of the other path increasing as the input wave amplitude increases, and a system associated with said paths for combining the energy from said paths.

13. The method of discriminating between electrical waves of different amplitudes which comprises dividing each wave into at least two portions, operating upon one portion to produce increasing output to input ratio thereof with increasing input wave amplitude, operating upon the other portion to maintain the output to input ratio thereof at least as low for high amplitude input waves as for low amplitude input waves, and recombining said portions so as to neutralize the effects of one portion.

14. The method of discriminating between electrical waves of different amplitudes, which comprises dividing each wave into at least two portions, operating upon one portion to increase and upon the other to decrease the output to input ratio thereof with increasing input wave amplitude, and recombining said portions so as to neutralize the effects of one portion.

15. In a device for separating desired from undesired oscillations, a plurality of coils in opposed relation, an output circuit operatively associated with said coils, a. symmetrical impedance device associated with one coil for causing it to present constant impedance to energy therein, and asymmetrical impedance devices associated with another coil for varying the impedance thereof to energy therein, the impedance of all of said devices being of finite values to all waves.

16. In a device for separating desired from undesired oscillations, a plurality of coils in opposed relation, an output circuit operatively associated with said coils, a symmetrical impedance device associated with one coil for causing it to present constant impedance to energy therein, and a pair of oppositely disposed asymmetrical devices associated with another coil for varying the impedance thereof to both half cycles of energy waves therein, the impedance of all of said devices being of finite values to all waves.

17. In a device for separating desired from un desired oscillations, a plurality of coils in opposed relation, an output circuit operatively associated with said coils, a resistor associated with one coil for causing it to present constant impedance to energy therein, and groups of rectifying devices associated with another coil for varying the impedance thereof to energy therein, the impedance of said resistor and of all of said devices being of finite values to all waves.

18. The method of separating desired from undesired oscillations which comprises operating a pair of coils in opposed relation to each other so that one presents finite constant impedance to energy therein while the other presents finite varying impedance to energy therein.

DAVID G. MCCAA.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2757281 *Dec 20, 1951Jul 31, 1956Le Bel Clarence JCircuit with extended logarithmic characteristic
US2867735 *Mar 7, 1955Jan 6, 1959Goldak CompanyBias control circuit
US2930005 *Jun 18, 1957Mar 22, 1960Philips CorpNetwork for frequency-modulated signals
US3086166 *Jan 8, 1959Apr 16, 1963Singer Inc H R BCubic function generator
US3189824 *Jan 9, 1961Jun 15, 1965Motorola IncNoise suppressors for radio receivers
US4300022 *Jul 9, 1979Nov 10, 1981Canadian Patents & Dev. LimitedMulti-filar moving coil loudspeaker
EP1678820A1 *Sep 29, 2004Jul 12, 2006Audio Products International Corp.Power amplifier and method for split voice coil transducer or speaker
Classifications
U.S. Classification323/299, 333/28.00R, 455/303
International ClassificationH04B1/12
Cooperative ClassificationH04B1/12
European ClassificationH04B1/12