US1078106A - Harmonic relay. - Google Patents

Harmonic relay. Download PDF


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US1078106A US50809609A US1909508096A US1078106A US 1078106 A US1078106 A US 1078106A US 50809609 A US50809609 A US 50809609A US 1909508096 A US1909508096 A US 1909508096A US 1078106 A US1078106 A US 1078106A
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Kempster B Miller
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Mcmeen & Miller
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Mcmeen & Miller
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    • H01H51/00Electromagnetic relays
    • H01H51/30Electromagnetic relays specially adapted for actuation by ac
    • H01H51/32Frequency relays; Mechanically-tuned relays
    • Y10S200/00Electricity: circuit makers and breakers
    • Y10S200/08Disturbance


APPLICATION FILED JULY 17, 1909 Patented Nov. 11, 1913.
Patented Nov. 11, 1913.
Specification of Letters Patent.
Application filed July-17, 1909.
Patented Nov. 11, 1913. Serial No. 508,096. 4
To all whom it may concern Be it known that LKEMPsTER B. MILLER, a citizen of the United States of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented a new and useful Improvement in Harmonic Relays, of which the following is aspecification.
My invention relates in general to apparatus and systems for accomplishing the selective operation among a plurality of devices connected with a single circuit or circuits, and in particular it relates to selective signaling on multi-party telephone lines. The general method which I employ to accomplish the selective operation among the several devices associated with a circuit or the several stations on a telephone party line, is to employ differently tuned reeds for each of the devices or stations associated with the circuit or line, each of these reeds being adapted to be set into vibration electro-magneticallyby a particular frequency of alternating or pulsating current flowing in the circuit or line to which the devices or stations are attached. My invention therefore comes within thescope of that class of systems, for the selective operation of devices, which has been termed harmonic in distinguishment from those classes which accomplish selection by step-by-step.movements,
or by changes in current strength or polarity, orby other means.
All of the successful systems of harmonic selection that have been used in telephony have employed electromagnets having tunedreed armatures carrying tappers which, when thrown into vibration, serve to strike directly against the gong orgongs to produce the desired sound. Such systems, wherein the gongs are struck by the direct action of the tuned reed, have been subject to certain defects which, while not suiticiently great to prevent their wide adoption,
able the bells to be successfully rung. In I have been present as objectionable features and have served at least to place a rather distinct limitation on the number of devices that could be successfully selectively operated over a single circuit. In one type of these direct acting harmonic bells ithas been found necessary to resort to what is called the under-tuning system in order to enthis type it has been found that when the tapper strikes the gong, the rebound of the tapper from the gong tends to accelerate the rate of vibration of the tuned reed-of which the tapper forms a part, and therefore to change the natural rate of vibration of the reed itself. If therefore the reed were tuned to accurately correspond with the frequency of current that was to operate it, the striking of the rapper against the gong would tend to accelerate the rate of vibration of the reed tongue, thus throwing it out of tune and causing irregular and in sufiicient ringingl To secure an effective ring, it has been the custom in this class of harmonic bells to give the reed tongue a natural rate of vibration slightly below the corresponding current. frequency, but yet suflicie'ntly close to it to enable the desired current frequency to start the reed sufiiciently to strike the gong, after which the accelerating influence of the gong brought the natural rate of the reed while striking the gong more nearly into unison with the operating striking harmonic bells the undertuning expedient has not been employed, the natural rate of vibration of the armature when not striking the gong being made to correspond as accurately as possible with the frequency of the operating current, and in this case special means have been adopted for preventing the gongs while being struck from exerting any great tendency to throw the reedtongue out of tune. In all of these direct striking methods of harmonic selective ringing however, the requirement exists that a comparatively large amount of energy be employed in the selecting current sent over the line, since this current must cause the bell armature that is actuated by it to strike the gongs with sufficient force to produce a loud, clear ringing of the bell. As the practice has been, and is, to employ a multiple or bridging relation of the bell coils with respect to the line, it follows that in the case of a long line the nearer bells to the source of ringing current must receive a great excess of current in order that the more remote hells may receive enough. This necessary employment of currents very much greater in strength than is necessary to ring some of the bells, at once sets up a condition which is favorable to cross ringing, that is, the ringing of bells not corresponding to the current frequency employed, by overcoming their natural tendency to vibrate at one frequency and force them, by sheer strength, to vibrate at another frequency. This imposes the re uirement that the frequencies employed di er widely one from another, and this in turn limits the number of stations that may be selectively operated.
Many attempts have been made to cause the harmonic device to act as arelay, and thus control the circuit of a responsive device, such as an ordinary vibrating bell. In all devices of this kind that have been proposed within my knowledge the tuned reed tongue has been caused, when thrown into vibration, to strike against contact points separately mounted. In some cases these contact points have been rigidly mounted and in other cases they have been yieldingly mounted, being usually carried .on springs or levers mounted independently of and separate from the reed tongue. In all these cases it has been found that the natural rate of vibration of the reed tongue has been altered by the striking against the contacts in the same manner that the rebound of the gongs in the direct-striking harmonic bells altered the natural rate of vibration. of their reed tongues. In addition to this, the closure of the circuit by such vibrating reeds has been intermittent, the circuit being closed and opened by each stroke of the reed.
My invention relates to harmonic devices which, when operated, serve to act as relays and thus perform their work indirectly through the control of another circuit rather than directly, as where the tuned tongue strikes directlyagainst the gongs. I avoid all of the difficulties that have been found in practice in the prior types of harmonic responsive devices by so arranging the reed tongue that the carrying out of its function is not dependent upon its striking against any object during its vibration. It carries a contact. closing device entirely within itself, which device assumes one condition of circuit control while the reed tongue is at rest, and another condition of circuit control when the reed tongue is in vibration, the change'being dependent on the state of rest or motion of the reed tongue and not upon its striking against or making contact with any external thing.
I have illustrated my invention in the acspective view of the vibrating part or reed tongue of my relay; F a is a sectional view of this vibrating part or reed tongue; Fig. 5 is a sectional'view of one form of contact closing device carried by the reed tongue; Fig. 6 is another form of contactclosing device; Figs. 7 and 8 are other modifications of the contact-closing device; Fig. 9 shows the circuit arrangement of a complete telephone party line employing my device; and Fig. 10 shows a modification of the telephone sub-stations of such a line; Fig. 11 shows another arrangement of line equipment..
Referring now to Figs. 1 and 2, which illustrate the preferred form of my har monic relay, 1-l represent the two spools of an electroniagnet, the cores 2 of which are connected to a soft iron yoke bar 3 which also forms a convenient means for attachment of the relay as a whole to its base. In order that the device may be more readily adaptable for alternating current work, I provide a polarizing magnet 4, which is preferably a permanently magnetized L-shapcd bar of steel attached to the yoke piece 3 and extending to a point in proximity to the rigid point of support of the armature. Over the polar ends of the cores 2 I force screwthreadcd metal collars 5, which at once form heads for the coil windings and an adjustable means of support for the arn'iature carrying yoke 6. This yoke 6 is held. rigidly on the collars 5 and therefore on the cores 2 by means of the two pairs of screw-threaded nuts 7-7 which engage the screw threads on the parts 5 and clamp the part 6 between them. In this way the entire yoke 6 may be moved longitudinally with respect to the cores, so that the armature 8 carried by the yoke may be moved closer to or farther from the pole pieces. The two downwardly projecting ears 6, of the yoke 6 areslotted to receive the screw-threaded shanks from the block 9 which supports the armature. This block 9 is held in place in the yoke 6 by the nuts 9.
The vibrating reed as a whole is shown in perspective view in Fig. 3 and in sectional viewin Fig. 4. The reed spring 10 is clamped directly against the supporting block 9 as indicated, and for this purpose this block may be either split or a separate block 9 may be used, this being held on the opposite side of the spring 10 from the block 9 by means of rivets or screws being as indicated. The armature r0 er, 8, in the form Iffhave illustrated, is two L-shaped pieces of soft iron, these being riveted together so as to include the free end of the spring 10 between them, and so also as to include the armature rod 12 which carries at its outer end the circuit controlling device 13.
I preferably make the armature rod 12- hollow so that it may carry within it, and insulated from it, a wire 11 forming the return side of the circuit leading to the circuitcontrolling device 13. The rod or tube 12 thus forms one side of the circuit leading to the circuit-controlling device, and the wire 14: Within this tube the return side of this circuit. In order that the wire 14: .may be carried directly from the end of the tube 12 without making contact with other metallic bodies, the reed spring 10 is offset from the line of the tube 12, as most clearly shown in Fig. 1. The wire 14 may thus pass in a direct line through a hole in the block 9, in which hole I preferably place an insulating bushing 15 to prevent electrical contact between the wire and the block.
The Wire 14 I preferably make of phosphor bronze, or other resilient metal so that it may partake of the slight bending to whichit is subjected when the armature is vibrated. An insulating tube 16 surrounds this wire throughout the entire length of the tube 12 and thus insulates it from that tube.
A preferred form of circuit-controlling device to be carried upon the outer end of the armature rod is illustrated in Fig. 5. This figure shows the upper end of the hollow rod 12 to have been expanded to form a chamber 17 of sufficient diameter to receive the current-controlling unit. The circuit-controlling device proper, as indicated in Fig. 5, is
comprised in the thimble 18 and the parts contained therein, these parts being removable from the chamber 17 bodily. The cap 18 is composed of iron, or it may be of electrolytic copper or aluminum. The downward projection 18 from. the center of. the inner surface of the cap 18 forms on electrode of the circuit-controlling device. This projection 18 may be of the same metal and integral with the body of the cap 18, or it may be in the form of a rivet as indicated in dotted lines in Fig. 5, in which case it might be of a different metal, such as platinum. The other electrode of the device is the metallic cup 20 which may be of iron, electrolytic copper, aluminum or platinum. This inner cup 20 forms a receptacle for a small drop' 21 of some conducting fluid such as mercury. The cup 20 is electrically insulated from the cap 18 by an insulating bushing 19, these three parts,the inner cup, the bushing and the cap, being forced together under considerable pressure so as to, as nearly as posormed of sible, hermetically seal the mercury contain ing chamber. The sealing of this chamber is further provided for bycoating the outer cylindrical surface of the inner cup 20 and the inner surface of the cap 18 with suitable cement before pressing these parts-together and by afterward filling the vacant space 22 between the inner and outer cups with a f cement which when set will form a nonporous m'ass resembling enamel. To the bottom of the cup, 20 is soldered or otherwise 1 secured the enlarged and flattened end of the conducting wire 1% which, as before stated, extends through the insulating bushing 16 within the tube 12 and forms the return circuit for the circuit controlling device.
The entire circuit-controlling device is held tightly in place within the chamber 17, either by the tightness of the fit in the construction illustrated or by providing screw threads on the inner surface of the chamber 17 and the outer surface of the cup 18,
\Vhen the harmonic relay is at rest, the drop of mercury or other fluid occupies the position shown and is therefore in contact only with the cup 20. As soon, however, as the reed tongue is thrown into vibration by the rhythmical action of an operating current vith which it is in tune, this drop of mercury is thrown. partly by centrifugal action and partly by the general churning up effect, to the top of the chamber in which position it makes contact also with the projection 18' from the cap 18, thus completing the circuit between the armature rod 12 and the inner 'con'dnctor 14. It will hold this circuit closed as long as the reed tongue continues to vibrate, and upon the cessation of vibration the mercury will drop back into the position shown, thus breaking the circuit.
Anot-her'form of circuit-controlling device is shown in Fig. 6. In this the mercury 22 is contained within the metallic cup Q3, which is flanged at its top. This cup is seated within an insulating bushing .24, which in turn rests within the enlargement or chamber 17 of the tube 12. The upper electrode is in this case a metal disk 25 separated and insulated from the cup 23 by the bushing 26. These parts are firmly bound together by screwing home .the cap 27, an internal screw thread in which, engages an external screw thread on the enlarged end of the tube 12. In order to provide as completely as possible for the hermetic sealing of the mercury chamber,-the insulating bushing or washer 26 is of a non-porous nature and is coated with a suitable cement before it is placed between the flange of the cup 23 and the disk 25, and the space 28 surrounding these parts is also filled with an enamel cement with the same end in view.
In some cases I may make the insulating bushing 19 of Fig. 5 or 26 of Fig. 6 of glass and fuse it by heat directly to the electrodes until after it has cooled off, then supplied through a small opening which is afterward properly sealed. 1
In Fig. 7 I have shown still another form of-circuit-controlling device. In this the mercury chamber 28 is all glass, through the walls of which two electrodes 29 and 30, preferably of platinum, project, being preferably sealed in. This entire capsule so formed may be secured within a suitable receptacle 31 carried by the armature rod 12, as by embodying it in some cement or wax which when set will present sufficient rigidity. Any tendency which the mercury may have to oxidize may of course be prevented by excluding the air from the capsule, and the forming of the capsule of glass, as indicated in Fig. 7, is advantageous from that standpoint.
So far in this specification I have referred to mercury or some other conducting fluid as the substance to be employed within the capsule for the purpose of completing the circuit bet-ween the two electrodes. 'As an alternative, very small particles of solid conducting material, such as carbon, or small metallic particles, may be used. These particles may be gold-plated to insure better contact and freedom from oxidation. In-
stead of employing a multitude of such solid conducting particles, I may employ a single metallic ball, preferably gold plated, as is shown in Fig. 8. Experiment has proven -that such a ball will, when the armature is thrown into vibration, rise within its chamber until it makes contact with the upper elect-rode. The employment of solid rather than fluid circuit-closing materials is advantageous in that the problem of hermetically sealing the chamber does not enter. The use of mercury however affords a surer means of closing the'circuit, there being no difliculty in this case, due to improper C011? tact. An efficient circuit closer is produced by amalgamating the ball of Fig. 8 with mercury, thus causing it to present at all times a surface wet with mercury.
The complete reed tongues carrying the circuit-controlling device may be tuned to respond to any frequency of operating current-by purely mechanical means. Itis obvious that the distance from the centers of gravity of the various moving parts of the vibrating structures and the effective pivotal point thereof will enter into the natural rate of vibration of the reed tongue as will also the weight of the several parts and the strength and length of-the reed spring. In order to vary the natural rate of vibration of any reed tongue, and to adjust it to the desired rate, I provide a weight 32 which is slidable upon the rod 12 and may be fixed harmonic bells, the range of frequency that it has been found feasible-to employ has been from about 16 cycles .per second as the lower limit and 66 cycles per second as the higher limit. Since my device is not limited by any requirement as to the sounding of the gong, I may employ a much wider range than this, and the range which I prefer is limited by about 16 cycles per second as the lower limit and 200 cycles per second as the higher limit. \Vithin this range I may employ a great number of frequencies with corresnondingly tuned reeds without danger of interference. I preferably make the mass of the mercury drop, or of whatever movable conductor I employ, very small in comparison with the mass of the moving parts of the vibrating reed, and also I preferably make the movement of this mass, toward or from the effective pivotal point of the reed tongue, as small as possible consistent with surety in making andbreakingthe circuit, in order that the moment of inertia of the entire reed tongue about its effective pivotal point may be altered to as small a degree as possible so that the change in center of gravity due to the slight displacement of the circuitclosing material in operation will not materially alter the natural rate of vibration of the reed tongue.
I have illustrated certain circuit arrangements in which my harmonic relay may be found useful in Fig. 9, this being a representation of a metallic circuit telephone line containing three stations, together with the terminal for this line in the central oflice, and the ringing apparatus at the central office. The line wires 40 and 41 extend from the spring jack 42 at the central office to the several telephone stations. At each of these stations there is shown, by the usual diagrammatic symbols, the telephone receiver and transmitter adapted to be bridged across the metallic circuit when the receiver is removed from the'switchhook for use, this arrangement being that commonly employed in the so-called common battery systems. I have shown at the central office one of the common arrangements for receiving signals from the stations. I have shown at each station one of my harmonic relays as 43 bridged across the line wires. Each of these relays when operated serves to. close the contact 45, thus completing the circuit through a polarized bell 46'.
At the central office I have shown three generators 46, 47 and 48, together wit-h the usual ringing keys for associating them with a cord circuit and the usual plug 49 for con necting thecord circuit with the sprin jack of any line.- These generators are a apted circuit b to generate alternating or pulsating current, each of a particular frequency, 1 the frequencies corresponding respectively to the natural ratesof vibration of the reed tongues of the relays 43, 43' and 43". If, there ore, the generator 46 is connected across the cord the corresponding ringing key, the current from that generator will pass over the metallic circuit and through the bridges at all of the stations in parallel. Only one of the relays, 43 for instance, will be operated, since that alone will have a reed tongue tuned to that particular frequency. The operation of this relay will close the contact 45 and thus cause the polarized bell 46' to receive current from the line and to be actuated thereby, these bells being adapted to respond to the same current that actua'tes the relay.
The telephone transmitters of the circuit of Fig. 9 are supposed to derive their cur'- rent from a central oflice battery in accordance with the usual common battery method of operation. Where desired however, a battery 49, local to each station, may serve to supply the transmitter current, and also may serve to ring a vibrating bell. 49 through the relay contact, this arrangement being indicated in Fig. 10.
A modification of the system of Fig. 9 is shown in Fig. 11. In this modification all of the polarized bells 50 are alike, and are adapted to be rung by a generator 50, of which three are shown at the central ofiice. In conjunction with each of the three ringing keys is shown a generator 46, 47, 48, respectively, producing current adapted to actuate the harmonic relays 46", 47", 48" respectively. Upon the actuation of any ringing key, twogenerators are placed upon the line in multiple, and two superimposed periodically varying currents pass over the line, one of which actuatcs the relay to close its contact and the other of which actuatcs the signal bell'through the relay contact. This is a desirable arrangement for the rea-.
- to the closing of circuits for the purpose of ringing telephone bells. It is adapted for use in telegraphy and in railway signaling systems, and in fact in any of the electrical arts wherever it is desired that a circuit shall be controlled or a device operated upon the sending of one particular frequency of current to the exclusion of all others.
It is obvious that change in the position of the mercury, or other movable circuit closin member carried by the reed, need not depen movement ,to' control the circuit. It is obvious that the contacts may be so arranged that any considerable vibration of the reed will so agitate the mercury or other fluid as to cause it to merely change its shape and thus close or open the break in the controlled circuit. I 'do not wish therefore to be limited in this respect to harmonic relays which depend on centrifugal action to throw the mercury or other circuit closing member into its alternate position, but I desire to include any arrangement by which the circuit-controlling member which is carried on the reed will assume and continuously hold one condition of circuit control while the reed is vibrating and another condition of circuit control while the reed is at rest.
It is obvious that the relays may have their contacts so arranged as to normally hold the circuit closed and to hold it continuously open when the reed is in vibration, such modification from the arrangement illustrated being well within the skill of the art in view of the disclosures herein made. It is also obvious that many changes may be made in the construction of the relay. Thus, instead of employing the type of magnetic circuit where the cores of the two operating coils are side by side and parallel, I may employ any of the other well-known magnetic circuits such, for instance, as that employed in the harmonic bell shown in patent to W. W. Dean No. 779,533, wherein the cores of the operating coils are placed in line with each other and present their poles to the opposite sides of what may be termed a straight-line armature.
. Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:
1. A relay; a vibratory member therefor; circuit-controlling contacts vibrating with said vibratory member, adapted to be held continuously in one condition of circuit control while said member is in vibration and continuously in another condition of circuit control while said member is at rest.
2. A'relay; a vibratory member therefor; circuit-closing contacts vibrating with said vibratory member, said contacts being held closed while said member is in vibration and open while said member is at rest.
3. In a relay, a vibrating reed; a pair of contacts carried by said reed, said contacts being electrically connected while said reed is vibrating and disconnected when said reed is at rest-.-
4. In a harmonic relay, a tuned reed armature therefor; a pair of contacts carried by said tuned reed armature, said contacts being insulated from each other while said turned reed armature is at rest and continu upon centrifugal action for its,
' ture therefor; a pair of contacts controlled by said tuned reed armature, said contacts being insulated from each other while said tunedreed armature is at rest and continuously electrically connected while said tuned reed armature is in vibration.
6. In a relay, a reed adapted to be electromagnetically vibrated; a circuit-controlling device carried on said reed, said circuit-controlling device being adapted to assume one condition of circuit control while said reed is at rest and another while said reed is being vibrated.
7. In a relay, a vibrating armature; an electrical switch carried by said armature; and centrifugally controlled means for closing said electrical switch.
8. In a relay, a vibrating armature; a contrifugally controlled electric switch carried by said armature and operated by reason of the vibratory movement thereof.
9. In a relay, a vibrating armature; a centrifugally movable conducting element carried by said armature; and other conducting elements fixed upon said armature and moving therewith and with which said movable element is adapted to make contact.
10. In a relay, an electromagnetically controlled vibrating part; a pair of contact members upon said vibrating part and const-itutin electrical terminals; a movable conducting element carried by said moving 3 part and adapted to connect said two contact members.
11. In a relay, an electromagnetically controlled vibrating part; a centrifugally controlled movable member upon said vibrating partand carried thereby; and fixed electrical contact members carried upon said vibrating part with which said centrifugally movable part may make contact.
12. In a relay, a vibratory member; .a 4 switch carried by said vibratory member; means for opening said switch when said vibratory member is at rest and for continuously closing said switch when said vibratory member is in motion.
13. A relay; a vibratory member therefor; circuit-controlling terminals carried on said vibratory member; a readily movable member also carried by said vibratory memberand adapted to connect said terminals While said vibratory member is in vibration.
Signed by me at Chicago, county of Cook and State of Illinois, in the presence of two witnesses.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2592770A (en) * 1947-02-08 1952-04-15 Macmillin Engineering Corp Variable-oscillator controlled relay system
US2690512A (en) * 1949-03-08 1954-09-28 Geophysique Cie Gle Vibratory motor
US2849562A (en) * 1953-08-06 1958-08-26 Peter V N Heller Acceleration responsive switch

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2592770A (en) * 1947-02-08 1952-04-15 Macmillin Engineering Corp Variable-oscillator controlled relay system
US2690512A (en) * 1949-03-08 1954-09-28 Geophysique Cie Gle Vibratory motor
US2849562A (en) * 1953-08-06 1958-08-26 Peter V N Heller Acceleration responsive switch

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