LESSON TWENTY-SEVEN. TELEPHONE RECEIVERS.Telephone receivers employed for wireless telegraphy are the same in principle as the ordinary telephone receiver but differ in construction and detail slightly.They are always of the watch case type, this style being small and light, and consist of a ring or horseshoe shaped permanent magnet upon the poles of which are mounted two small bobbins containing many turns of fine insulated wire. Over the magnets, very close to but not quite touching, is placed a circular diaphram of thin sheet iron. The lines of force created by the permanent magnet pass through the cores of the little bobbin and exert a constant pull on the diaphram.The little bobbins of wire or electromagnets are connected in series. If a current of electricity is sent through them they will create a little field of force of their own which will strengthen or decrease that of the permanent magnets according in which direction the current flows. Each change in the pull exerted on the diaphragm causes it to move and send out little sound waves which may be heard when the receiver is held close.We have already learned that the strength of a magnet depends upon theampereturns. Suppose that a current of one ampere passed through a coil containing 100turnsx 1amp.= 100ampere turns. If only one-tenth of an ampere was available and we wished to retain the same magnetic strength in the coil, the number of turns would have to be increased to one thousand in order for the ampere turns to remain equal; 1/10amp.x 1.000turns= 100ampere turns.FIG. 57. Types of Telephone Head Sets.FIG. 57. Types of Telephone Head Sets.The currents passing through the receiver from the detector are exceedingly weak, and so in order to produce the maximum effect on the diaphragm, the electromagnets must be wound with a large number of turns of very fine wire. The resistance of fine wire is very great and for this reason wireless telephone receivers are usually termedhigh resistance receivers.Winding a receiver with many turns of fine wire does not make it more sensitive in the true sense of the word or from the standpoint of efficiency, but makes it better suited to the minute fluctuations of a weak current.The classification of receivers, according to their resistance is a method of indicating the comparative number of turns and the finess of the wire used in winding the electromagnets. Receivers should be wound with copper wire only.Wireless receivers come in pairs provided with a head-band so that they may be securely clamped on the ears.The receiver cases are made of rubber, composition, brass and aluminum depending upon the design and manufacture. It is immaterial which.
LESSON TWENTY-SEVEN. TELEPHONE RECEIVERS.Telephone receivers employed for wireless telegraphy are the same in principle as the ordinary telephone receiver but differ in construction and detail slightly.They are always of the watch case type, this style being small and light, and consist of a ring or horseshoe shaped permanent magnet upon the poles of which are mounted two small bobbins containing many turns of fine insulated wire. Over the magnets, very close to but not quite touching, is placed a circular diaphram of thin sheet iron. The lines of force created by the permanent magnet pass through the cores of the little bobbin and exert a constant pull on the diaphram.The little bobbins of wire or electromagnets are connected in series. If a current of electricity is sent through them they will create a little field of force of their own which will strengthen or decrease that of the permanent magnets according in which direction the current flows. Each change in the pull exerted on the diaphragm causes it to move and send out little sound waves which may be heard when the receiver is held close.We have already learned that the strength of a magnet depends upon theampereturns. Suppose that a current of one ampere passed through a coil containing 100turnsx 1amp.= 100ampere turns. If only one-tenth of an ampere was available and we wished to retain the same magnetic strength in the coil, the number of turns would have to be increased to one thousand in order for the ampere turns to remain equal; 1/10amp.x 1.000turns= 100ampere turns.FIG. 57. Types of Telephone Head Sets.FIG. 57. Types of Telephone Head Sets.The currents passing through the receiver from the detector are exceedingly weak, and so in order to produce the maximum effect on the diaphragm, the electromagnets must be wound with a large number of turns of very fine wire. The resistance of fine wire is very great and for this reason wireless telephone receivers are usually termedhigh resistance receivers.Winding a receiver with many turns of fine wire does not make it more sensitive in the true sense of the word or from the standpoint of efficiency, but makes it better suited to the minute fluctuations of a weak current.The classification of receivers, according to their resistance is a method of indicating the comparative number of turns and the finess of the wire used in winding the electromagnets. Receivers should be wound with copper wire only.Wireless receivers come in pairs provided with a head-band so that they may be securely clamped on the ears.The receiver cases are made of rubber, composition, brass and aluminum depending upon the design and manufacture. It is immaterial which.
LESSON TWENTY-SEVEN. TELEPHONE RECEIVERS.Telephone receivers employed for wireless telegraphy are the same in principle as the ordinary telephone receiver but differ in construction and detail slightly.They are always of the watch case type, this style being small and light, and consist of a ring or horseshoe shaped permanent magnet upon the poles of which are mounted two small bobbins containing many turns of fine insulated wire. Over the magnets, very close to but not quite touching, is placed a circular diaphram of thin sheet iron. The lines of force created by the permanent magnet pass through the cores of the little bobbin and exert a constant pull on the diaphram.The little bobbins of wire or electromagnets are connected in series. If a current of electricity is sent through them they will create a little field of force of their own which will strengthen or decrease that of the permanent magnets according in which direction the current flows. Each change in the pull exerted on the diaphragm causes it to move and send out little sound waves which may be heard when the receiver is held close.We have already learned that the strength of a magnet depends upon theampereturns. Suppose that a current of one ampere passed through a coil containing 100turnsx 1amp.= 100ampere turns. If only one-tenth of an ampere was available and we wished to retain the same magnetic strength in the coil, the number of turns would have to be increased to one thousand in order for the ampere turns to remain equal; 1/10amp.x 1.000turns= 100ampere turns.FIG. 57. Types of Telephone Head Sets.FIG. 57. Types of Telephone Head Sets.The currents passing through the receiver from the detector are exceedingly weak, and so in order to produce the maximum effect on the diaphragm, the electromagnets must be wound with a large number of turns of very fine wire. The resistance of fine wire is very great and for this reason wireless telephone receivers are usually termedhigh resistance receivers.Winding a receiver with many turns of fine wire does not make it more sensitive in the true sense of the word or from the standpoint of efficiency, but makes it better suited to the minute fluctuations of a weak current.The classification of receivers, according to their resistance is a method of indicating the comparative number of turns and the finess of the wire used in winding the electromagnets. Receivers should be wound with copper wire only.Wireless receivers come in pairs provided with a head-band so that they may be securely clamped on the ears.The receiver cases are made of rubber, composition, brass and aluminum depending upon the design and manufacture. It is immaterial which.
Telephone receivers employed for wireless telegraphy are the same in principle as the ordinary telephone receiver but differ in construction and detail slightly.
They are always of the watch case type, this style being small and light, and consist of a ring or horseshoe shaped permanent magnet upon the poles of which are mounted two small bobbins containing many turns of fine insulated wire. Over the magnets, very close to but not quite touching, is placed a circular diaphram of thin sheet iron. The lines of force created by the permanent magnet pass through the cores of the little bobbin and exert a constant pull on the diaphram.
The little bobbins of wire or electromagnets are connected in series. If a current of electricity is sent through them they will create a little field of force of their own which will strengthen or decrease that of the permanent magnets according in which direction the current flows. Each change in the pull exerted on the diaphragm causes it to move and send out little sound waves which may be heard when the receiver is held close.
We have already learned that the strength of a magnet depends upon theampereturns. Suppose that a current of one ampere passed through a coil containing 100turnsx 1amp.= 100ampere turns. If only one-tenth of an ampere was available and we wished to retain the same magnetic strength in the coil, the number of turns would have to be increased to one thousand in order for the ampere turns to remain equal; 1/10amp.x 1.000turns= 100ampere turns.
FIG. 57. Types of Telephone Head Sets.FIG. 57. Types of Telephone Head Sets.
FIG. 57. Types of Telephone Head Sets.
The currents passing through the receiver from the detector are exceedingly weak, and so in order to produce the maximum effect on the diaphragm, the electromagnets must be wound with a large number of turns of very fine wire. The resistance of fine wire is very great and for this reason wireless telephone receivers are usually termedhigh resistance receivers.
Winding a receiver with many turns of fine wire does not make it more sensitive in the true sense of the word or from the standpoint of efficiency, but makes it better suited to the minute fluctuations of a weak current.
The classification of receivers, according to their resistance is a method of indicating the comparative number of turns and the finess of the wire used in winding the electromagnets. Receivers should be wound with copper wire only.
Wireless receivers come in pairs provided with a head-band so that they may be securely clamped on the ears.
The receiver cases are made of rubber, composition, brass and aluminum depending upon the design and manufacture. It is immaterial which.