Electric bell

“ I started from my chair and listened intently, but the ringing had stopped, and I settled back to the delights of a nervous chill, when again the deathly silence of the night—the wind had quieted in time to allow me the use of this faithful, overworked phrase—was broken by the tintinnabulation of the bell. This time I recognized it as the electric bell operated by a push-button upon the right side of my front door. To rise and rush to the door was the work of a moment. It always is. ”

“ It is frequently necessary to have an electric bell which, when once started, will continue ringing until it is stopped. Such bells are used for fire and burglar alarms and for many other similar purposes, and they are called continuous-ringing bells as distinguished from the ordinary trembler bells. ”

“ In connection with the armature and clapper is a device whereby the flow of the current can be rapidly interrupted, so that on the cessation of the current the iron may lose its magnetism, and allow the spring to withdraw the clapper from against the bell. This device is known as the "contact breaker" and varies somewhat in design, according to whether the bell belongs to the trembling, the single stroke, or the continuous ringing class.
§ 42. In order that the electric bell-fitter may have an [Pg 60] intelligent conception of his work, he should make a small electric bell himself. ”

“ Among all the applications of electricity to domestic or commercial uses, few are as widespread as the electric bell. Practically every building used for a dwelling, storage or manufacture requires an electric bell, annunciator or alarm system. ”

“ In the days of wire-pulled bells it was necessary to have quite a battery of bells of different tones for different rooms, but a single electric bell can be rung from bell-pushes119 placed in any part of a house or hotel. An indicator is used to show which push has been pressed, and, this like the bell itself, depends upon the attraction of an armature by an electro-magnet. Before reaching the bell the wire from each bell-push passes round a separate small electro-magnet, which is thus magnetized by the current at the same time that the bell is rung. ”

“ An electric bell depends for its action on the fact that a piece of iron wound with insulated wire becomes a magnet and will attract another piece of iron just so long as an electric current is allowed to travel through the wire.
The instant the current ceases, the magnetism also ceases, and the attracted piece of iron (termed the armature) is no longer held in contact. ”

“ So rapidly has the use of electric bells and similiar signalling appliances extended, in modern houses, offices, hotels, lifts, and ships, that every bell-fitter must have felt the need of accurate knowledge of the manner in which these instruments act and are made. ”

“ Magneto Signal Bells, Fig. 123, are used as generator and bell in connection with telephones. The generator, used to ring a bell at a distant station, stands at the bottom of the box. The [94] bell is fastened to the lid, and receives current from a distant bell.
118. Electric Buzzers have the same general construction as electric bells; in fact, you will have a buzzer by removing the bell from an ordinary electric bell. Buzzers are used in places where the loud sound of a bell would be objectionable. Fig. ”

“ The bell is an ordinary electric bell, and is rung by the regulating clock, which closes the circuit at the instant the signal is desired. The flashing-signal consists of a red vertical disk on a vertical axis, which normally shows only its edge, but is made to revolve once on its axis in four sudden jumps, by simple mechanism in connection with electro-magnets, when the regulator, by closing the circuit, sends the current. ”

“ However good may be the bells, indicators, batteries, etc., used in an electric bell installation, if the wiring be in any wise faulty, the system will surely be continually breaking down, and giving rise to dissatisfaction. It is therefore of the highest importance that the workman, if he value his good name, should pay the greatest attention to ensure that this part of his work be well and thoroughly done. ”

“ In the old system, which has been largely superseded by pneumatic and still more by electric bells, the bells themselves are of the ordinary conical shape and are provided with clappers hung loosely inside them. Being supported on springs they continue to swing, and therefore to give out sound as the clapper knocks against the sides, for some time after they have been set in motion by means of the strings or wires by which each is connected to a bell-pull in the rooms. ”

“ In the admirable series of papers on electric bell fitting which was published in the English Mechanic, Mr. F. C. Allsop, speaking of the Leclanché cell, says:—"A severe and prolonged test, extending over many years, has proved that for general electric bell work the Leclanché has no equal; though, in large hotels, etc., where the work is likely to be very heavy, it may, perhaps, be preferable to employ a form of the Fuller bichromate battery. ”

“ The Electric Bell and Buzzer (Fig. 38) .—So common a thing as an electric bell really belongs to [72] the present generation. Bells were either novelties or toys when I was your age. They cost then many times what they do now and then were poorly made. ”

“ A property of current electricity, which is the fundamental basis of electric bell-ringing, is that of conferring upon iron and steel the power of attracting iron and similar bodies, or, as it is usually said, of rendering iron magnetic. If a soft iron rod, say about 4" long by 1⁄2" diameter, be wound evenly from end to end with three or four layers of cotton-covered copper wire, say No. 20 gauge, and placed in proximity to a few iron nails, etc., no attractive power will be evinced ”

“ The rapidity with which the electric bell-push has taken the place of the old-fashioned knocker and the bell-hanger's system affords one indication of the readiness with which those forms of electric apparatus which are adapted to all the purposes of communicating and reminding will recommend themselves to the public during the twentieth century. ”

“ The conveyance of sound by means of an electric wire, has been practised through the instrumentality of the bell telegraph, used occasionally, though much less frequently than apparatus of a different kind. The signaller does not himself ring a bell, but sets in vibration a bell at the further or receiving end of the wire. The electric current, passing through the wire, acts upon a small magnet, and this in its turn acts upon a small bell or its hammer. By a preconcerted arrangement, one single sound is understood to denote a particular letter or word ”

“ The dynamo rotates under the still more subtile influence of an electric current which may also cause the click of a telegraph instrument or the ring of an electric bell, but the dynamo ceases its swift whirl and the persistent ring of the electric bell becomes mute when the invisible electricity is switched off. The form of the bird, the animal and the human being also cease their motion when the inner force which we call life has winged its invisible way. ”

“ That an electro-magnet could vibrate a tuning-fork and so produce sound was an entirely new and fascinating idea to the youth. It appealed to his imagination, quickened by his knowledge of speech. "Why not an electrical telegraph?" he asked himself. His idea seems to have been that the electric current could carry different notes over the wire and reproduce them by means of the electro-magnet. Although Bell did not know it, many others were struggling with the same problem, the answer to which proved most elusive. It gave Bell a starting-point, and the search for the telephone began. ”

“ A little while ago I received a telephone message to the effect that . . . ah!” he exclaimed. An electric bell had sounded in the distance. “Let us wait.” He smiled as he took out his cigarette case, but the fingers that presently held the match were not much steadier than hers. “Listen, listen!” he muttered.
In spite of herself Kitty listened. At first her ears could detect nothing; then they heard the closing of a distant, heavy door. A brief period of silence was followed by the sound, faint to begin with, of slow, heavy footfalls. Soon she realized they were descending a stone stair. ”

“ The best system for operating bells and annunciators from alternating current circuits is undoubtedly that employing small specially constructed transformers to reduce the voltage. These transformers are being used universally for hotel and office work where alternating current is available. They are simple, being merely one or more coils of well insulated wire wound on soft iron cores and having connections for both the lighting circuit and the bell circuit. ”

“ In the following pages the author has attempted to supply this need, by giving full details as to the construction of batteries, bells, pushes, detectors, etc., the mode of wiring, testing, connecting up, localizing faults, and, in point of fact, by directing careful attention to every case that can present itself to the electric-bell fitter. ”

“ When the key K is depressed an intermittent current from the main battery B is directed to the line-wire W, and passes through the electro-magnet E of a receiving instrument R at the distant end of the circuit, and thence to the ground G. The steel reed A is placed in front of the receiving magnet, and when its normal rate of vibration is the same as the reed of the transmitting instrument it is thrown into powerful vibration, emitting a musical tone of a similar pitch to that produced by the reed of the transmitting instrument, but if it is normally of a different pitch it remains silent. ”

“ It should also be mentioned that Gore [20] obtained loud musical notes from mercury, accompanied by singularly beautiful crispations of the surface during the course of experiments in electrolysis; Page [21] produced musical tones from Trevelyan’s bars by the action of the galvanic current; and further it was discovered by Sullivan [22] that a current of electricity is generated by the vibration of a wire composed partly of one metal and partly of another. The current was produced so long as the wire emitted a musical note, but stopped immediately upon the cessation of the sound. ”

“ If the wire used to wind the electro-magnet be old, badly covered, or bared in several places in winding, it probably will allow the current to "short circuit," instead of traversing the whole length of the coils. If this be the case, the magnet will be very weak: the magnet of a 21⁄2-in. bell should be able to sustain easily a 1 lb. weight attached by a piece of string to a smooth piece of 1⁄2-in. square iron placed across its poles, when energized by a single pint Leclanché cell. If it will not do this, the insulation may be suspected. ”

“ But when this battery came to be put to the test of practical work, it was found the block form could not be credited with all these advantages, and that their chief superiority over the old cell consisted rather in their lower internal resistance than in anything else. Even this is not an advantage in the case of bell work, except when several bells are arranged in parallel, so that a large current is required. The blocks certainly polarise more quickly than the old form, and it does not appear that they depolarise any more rapidly. ”

“ Whenever possible, the wiring of a house, etc., for bell work, should be done as soon as the walls are up and the roof is on. The shortest and straightest convenient route from bell to battery, etc., should always be chosen where practicable to facilitate drawing the wire through and to avoid the loss of current which the resistance of long lengths of wire inevitably entails. The wires should be run in light zinc tubes nailed to the wall. ”

“ Portable Electric Combination Bell is a unique invention combining a table call bell, invalids’ bell set, burglar alarm and fire alarm, and for usefulness, compactness, and finish, far surpasses anything of the sort hitherto introduced. The distinct advantage of the portable combination bell will at once be seen when it is stated that the whole apparatus, including battery, and all other parts complete, occupies no greater space than 31⁄2 in., and as the battery contains no fluid, the bell can be safely packed in portmanteau or travelling bag. ”

“ Without the telegraph the railway would be shorn of far more than half its efficiency, and the press of even metropolitan cities would shrink to provincial dimensions. It is becoming difficult to conceive what the state of business would be without even the telephone, which, in every large city, does the work of a whole army of messenger boys. How little we think of electricity when we press the button that closes an electric circuit and rings a bell 1 Yet the electric bell is certainly one of the most convenient of so-called modern improvements. ”

“ This continual making and breaking of the circuit keeps up as long as the push is pressed, a ball mounted on A by means of a rod strikes against the gong G causing a continuous ringing of the bell. The wires leading between the bell, battery cell and push must all be insulated, that is, covered with cotton, rubber, etc., which prevents the leakage of current should two wires cross each other. Copper wire is mostly used for circuits indoors, the details of the kind and size of wire will be given later on. ”

“ It was left for John Smeaton, of Eddystone Lighthouse fame, to introduce the air-pump as an auxiliary, which, by making the pressure of the air inside the bell equal to that of the water outside, kept the bell quite free of water. Smeaton replaced Halley's tub by a square, solid cast-iron box, 50 cwt. in weight, large enough to accommodate two men at a time. The modern bell is merely an enlarged edition of this type, furnished with telephones, electric lamps, and, in some cases, with a special air-lock, into which the men may pass when the bell is raised. ”