CHAPTER XV A WIRELESS TELEPHONEProbably many readers of the "Boy Electrician" are amateur wireless operators and have constructed their own apparatus with which they are able to pick up commercial messages or communicate with other experimenters in the neighborhood, but not many have ever built a wireless telephone.The device described in the following pages is easy to make and arrange, and will serve for some very interesting experiments.It is of no practical value as a commercial wireless telephone, because the distance over which it will transmit speech is limited to from 250 to 300 feet. If you have a chum who lives across the street and within the distance named above, it is possible for you to construct a simple wireless telephone which will enable you to remain in your own rooms and talk to each other without any connecting wires.The instruments operate by magnetic induction. It has already been explained how it is possible for the current in the primary of an induction coil to induce a current in the secondary coil, even though the two are not electrically connected. This type of wireless telephone really consists of an induction coil in which the two windings are widely separated.Suppose that two coils of wire are connected as in Figure 237. The illustration shows that one coil,A, is connected in series with a set of batteries and a telegraph key. The terminals of the other coil,B, are connected to a telephone receiver. The coils are placed parallel to each other and a few inches apart. If the key is pressed so that the battery current may flow through the coil,A, it will create a magnetic field, and lines of force will be set up in the immediate vicinity. The lines of force will pass through the coil,B, and induce in it a current of electricity which will cause a sound like a click to be heard in the telephone receiver.Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.If a telephone transmitter is substituted for the key and words are spoken into it, the current passing through the coil from the battery will vary with each vibration of the voice and the words will be distinctly repeated by the receiver connected toB.This experiment may be tried by any boy with the equipment he probably has already around his shop. Twenty-five to thirty turns of wire wound around a cardboard tube five or six inches in diameter will serve as a coil. Two such coils, an ordinary telephone transmitter, a telephone receiver and a couple of dry cells are all that is required.Fig. 238.—A Simple Wireless Telephone.Fig. 238.—A Simple Wireless Telephone. Speech directed into the Transmitter can be heard in the Receiver, although there is no direct electrical connection between the two.The diagram in the accompanying illustration shows how the apparatus is arranged. The coils may be used several inches apart and the voice will be clearly heard in the receiver.Such an outfit is, however, only experimental, and if it is desired to make a practical set, the coils, etc., must be much larger in diameter and contain a greater number of turns.Larger coils are made by first drawing a circle four feet in diameter on the floor of the "shop" or attic. Then drive a number of small nails around the circumference, about four inches apart.Procure two and one-half pounds of No. 20 B. & S. gauge cotton-covered magnet wire and wind it around the circumference of the circle. The wire should form at least sixty complete turns. About one foot should be left at each end to establish connections with. After winding, the coil should be tied about every six inches with a small piece of string so that it will retain its shape and not come apart. The nails are then pulled out so that the coil may be removed.The coil may be used just as it is for experimental purposes, but if it is intended for any amount of handling it is wise to procure a large hoop such as girls use for rolling along the sidewalk, and make the coil the same diameter as the hoop so that upon completion they may be firmly bound together with some insulating tape. Two binding-posts may then be fastened to the hoop and the terminals of the coil connected to them.Two such coils are required for a complete wireless telephone system, one to be located at each station.It is also necessary to make a double-contact strap-key. Such a key is easily built out of a few screws and some sheet-brass. The illustration shows the various parts and construction so clearly that no detailed explanation is necessary.Fig. 239.—A Double-Contact Strap-Key.Fig. 239.—A Double-Contact Strap-Key. The Dotted Lines show how the Binding-Posts are connected.The telephone transmitter and the telephone receiver required for this experiment must be very sensitive, and it is hardly possible for the young experimenter to build one which will be satisfactory. They can be secured from a second-hand telephone or purchased at an electrical supply house. The transmitter should be of the "long distance" type. An 80-ohm receiver will serve the purpose, but if you also have a wireless station, use the same 1000-ohm receivers belonging to your wireless set and you will secure very good results.A battery capable of delivering about 10 volts and a good constant current is required.The apparatus is connected as shown in Figure 240.When the key is pressed, the coil is connected to the battery and the telephone transmitter. If words are then spoken into the transmitter they will vary the amount of current flowing and the magnetic field which is set up in the neighborhood of the coil will induce currents in the coil at the other station, provided that it is not too far away, and cause the words to be reproduced in the telephone receiver.When the key is released it will connect with the upper contact and place the telephone receiver in the circuit for receiving, so that your chum at the other station can answer your message by pressing his key and talking into his transmitter.Fig. 240.—The Circuit of the Wireless Telephone.Fig. 240.—The Circuit of the Wireless Telephone. When the Key is up, the Receiver is ready for Action. When the Key is pressed, the Transmitter and Battery are thrown into the Circuit.The best plan is to mount each of the coils upon a tripod and experiment by placing them close together at first and gradually moving them apart until the maximum distance that the apparatus will work is discovered.Be very careful to keep the two coils exactly parallel.Much depends upon the battery. Be certain that it is capable of delivering a good strong current. Do not hold the key down any longer than is absolutely necessary, or the telephone transmitter will become hot.By making the coils six feet in diameter and placing from 200 to 400 turns of wire in each coil you can make a set which is capable of transmitting speech 300 feet or more.Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs.Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs. 1. The Telephone Coil. 2. The Telephone Transmitter. 3. Double-Contact Strap-Key. 4. The Battery. 5. Spark Coil. 6. Key. 7. Spark-Gap. 8. Aerial Switch. 9. Loose Coupler. 10. Detector, 11. Fixed Condenser. 12. Code Chart. 13. Amateur License. 14. Aerial. 15. Telephone Receivers.The coil may be mounted on the wall of your shop in a position where it will be parallel to one located in your chum’s house.The success of a wireless telephone system of this sort lies in making the coils of large diameter and many turns, in keeping the coils parallel, using a sensitive transmitter and receiver, and in employing a good strong battery. Storage cells are the best for the purpose.ELECTRIC MOTORS
CHAPTER XV A WIRELESS TELEPHONEProbably many readers of the "Boy Electrician" are amateur wireless operators and have constructed their own apparatus with which they are able to pick up commercial messages or communicate with other experimenters in the neighborhood, but not many have ever built a wireless telephone.The device described in the following pages is easy to make and arrange, and will serve for some very interesting experiments.It is of no practical value as a commercial wireless telephone, because the distance over which it will transmit speech is limited to from 250 to 300 feet. If you have a chum who lives across the street and within the distance named above, it is possible for you to construct a simple wireless telephone which will enable you to remain in your own rooms and talk to each other without any connecting wires.The instruments operate by magnetic induction. It has already been explained how it is possible for the current in the primary of an induction coil to induce a current in the secondary coil, even though the two are not electrically connected. This type of wireless telephone really consists of an induction coil in which the two windings are widely separated.Suppose that two coils of wire are connected as in Figure 237. The illustration shows that one coil,A, is connected in series with a set of batteries and a telegraph key. The terminals of the other coil,B, are connected to a telephone receiver. The coils are placed parallel to each other and a few inches apart. If the key is pressed so that the battery current may flow through the coil,A, it will create a magnetic field, and lines of force will be set up in the immediate vicinity. The lines of force will pass through the coil,B, and induce in it a current of electricity which will cause a sound like a click to be heard in the telephone receiver.Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.If a telephone transmitter is substituted for the key and words are spoken into it, the current passing through the coil from the battery will vary with each vibration of the voice and the words will be distinctly repeated by the receiver connected toB.This experiment may be tried by any boy with the equipment he probably has already around his shop. Twenty-five to thirty turns of wire wound around a cardboard tube five or six inches in diameter will serve as a coil. Two such coils, an ordinary telephone transmitter, a telephone receiver and a couple of dry cells are all that is required.Fig. 238.—A Simple Wireless Telephone.Fig. 238.—A Simple Wireless Telephone. Speech directed into the Transmitter can be heard in the Receiver, although there is no direct electrical connection between the two.The diagram in the accompanying illustration shows how the apparatus is arranged. The coils may be used several inches apart and the voice will be clearly heard in the receiver.Such an outfit is, however, only experimental, and if it is desired to make a practical set, the coils, etc., must be much larger in diameter and contain a greater number of turns.Larger coils are made by first drawing a circle four feet in diameter on the floor of the "shop" or attic. Then drive a number of small nails around the circumference, about four inches apart.Procure two and one-half pounds of No. 20 B. & S. gauge cotton-covered magnet wire and wind it around the circumference of the circle. The wire should form at least sixty complete turns. About one foot should be left at each end to establish connections with. After winding, the coil should be tied about every six inches with a small piece of string so that it will retain its shape and not come apart. The nails are then pulled out so that the coil may be removed.The coil may be used just as it is for experimental purposes, but if it is intended for any amount of handling it is wise to procure a large hoop such as girls use for rolling along the sidewalk, and make the coil the same diameter as the hoop so that upon completion they may be firmly bound together with some insulating tape. Two binding-posts may then be fastened to the hoop and the terminals of the coil connected to them.Two such coils are required for a complete wireless telephone system, one to be located at each station.It is also necessary to make a double-contact strap-key. Such a key is easily built out of a few screws and some sheet-brass. The illustration shows the various parts and construction so clearly that no detailed explanation is necessary.Fig. 239.—A Double-Contact Strap-Key.Fig. 239.—A Double-Contact Strap-Key. The Dotted Lines show how the Binding-Posts are connected.The telephone transmitter and the telephone receiver required for this experiment must be very sensitive, and it is hardly possible for the young experimenter to build one which will be satisfactory. They can be secured from a second-hand telephone or purchased at an electrical supply house. The transmitter should be of the "long distance" type. An 80-ohm receiver will serve the purpose, but if you also have a wireless station, use the same 1000-ohm receivers belonging to your wireless set and you will secure very good results.A battery capable of delivering about 10 volts and a good constant current is required.The apparatus is connected as shown in Figure 240.When the key is pressed, the coil is connected to the battery and the telephone transmitter. If words are then spoken into the transmitter they will vary the amount of current flowing and the magnetic field which is set up in the neighborhood of the coil will induce currents in the coil at the other station, provided that it is not too far away, and cause the words to be reproduced in the telephone receiver.When the key is released it will connect with the upper contact and place the telephone receiver in the circuit for receiving, so that your chum at the other station can answer your message by pressing his key and talking into his transmitter.Fig. 240.—The Circuit of the Wireless Telephone.Fig. 240.—The Circuit of the Wireless Telephone. When the Key is up, the Receiver is ready for Action. When the Key is pressed, the Transmitter and Battery are thrown into the Circuit.The best plan is to mount each of the coils upon a tripod and experiment by placing them close together at first and gradually moving them apart until the maximum distance that the apparatus will work is discovered.Be very careful to keep the two coils exactly parallel.Much depends upon the battery. Be certain that it is capable of delivering a good strong current. Do not hold the key down any longer than is absolutely necessary, or the telephone transmitter will become hot.By making the coils six feet in diameter and placing from 200 to 400 turns of wire in each coil you can make a set which is capable of transmitting speech 300 feet or more.Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs.Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs. 1. The Telephone Coil. 2. The Telephone Transmitter. 3. Double-Contact Strap-Key. 4. The Battery. 5. Spark Coil. 6. Key. 7. Spark-Gap. 8. Aerial Switch. 9. Loose Coupler. 10. Detector, 11. Fixed Condenser. 12. Code Chart. 13. Amateur License. 14. Aerial. 15. Telephone Receivers.The coil may be mounted on the wall of your shop in a position where it will be parallel to one located in your chum’s house.The success of a wireless telephone system of this sort lies in making the coils of large diameter and many turns, in keeping the coils parallel, using a sensitive transmitter and receiver, and in employing a good strong battery. Storage cells are the best for the purpose.ELECTRIC MOTORS
CHAPTER XV A WIRELESS TELEPHONEProbably many readers of the "Boy Electrician" are amateur wireless operators and have constructed their own apparatus with which they are able to pick up commercial messages or communicate with other experimenters in the neighborhood, but not many have ever built a wireless telephone.The device described in the following pages is easy to make and arrange, and will serve for some very interesting experiments.It is of no practical value as a commercial wireless telephone, because the distance over which it will transmit speech is limited to from 250 to 300 feet. If you have a chum who lives across the street and within the distance named above, it is possible for you to construct a simple wireless telephone which will enable you to remain in your own rooms and talk to each other without any connecting wires.The instruments operate by magnetic induction. It has already been explained how it is possible for the current in the primary of an induction coil to induce a current in the secondary coil, even though the two are not electrically connected. This type of wireless telephone really consists of an induction coil in which the two windings are widely separated.Suppose that two coils of wire are connected as in Figure 237. The illustration shows that one coil,A, is connected in series with a set of batteries and a telegraph key. The terminals of the other coil,B, are connected to a telephone receiver. The coils are placed parallel to each other and a few inches apart. If the key is pressed so that the battery current may flow through the coil,A, it will create a magnetic field, and lines of force will be set up in the immediate vicinity. The lines of force will pass through the coil,B, and induce in it a current of electricity which will cause a sound like a click to be heard in the telephone receiver.Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.If a telephone transmitter is substituted for the key and words are spoken into it, the current passing through the coil from the battery will vary with each vibration of the voice and the words will be distinctly repeated by the receiver connected toB.This experiment may be tried by any boy with the equipment he probably has already around his shop. Twenty-five to thirty turns of wire wound around a cardboard tube five or six inches in diameter will serve as a coil. Two such coils, an ordinary telephone transmitter, a telephone receiver and a couple of dry cells are all that is required.Fig. 238.—A Simple Wireless Telephone.Fig. 238.—A Simple Wireless Telephone. Speech directed into the Transmitter can be heard in the Receiver, although there is no direct electrical connection between the two.The diagram in the accompanying illustration shows how the apparatus is arranged. The coils may be used several inches apart and the voice will be clearly heard in the receiver.Such an outfit is, however, only experimental, and if it is desired to make a practical set, the coils, etc., must be much larger in diameter and contain a greater number of turns.Larger coils are made by first drawing a circle four feet in diameter on the floor of the "shop" or attic. Then drive a number of small nails around the circumference, about four inches apart.Procure two and one-half pounds of No. 20 B. & S. gauge cotton-covered magnet wire and wind it around the circumference of the circle. The wire should form at least sixty complete turns. About one foot should be left at each end to establish connections with. After winding, the coil should be tied about every six inches with a small piece of string so that it will retain its shape and not come apart. The nails are then pulled out so that the coil may be removed.The coil may be used just as it is for experimental purposes, but if it is intended for any amount of handling it is wise to procure a large hoop such as girls use for rolling along the sidewalk, and make the coil the same diameter as the hoop so that upon completion they may be firmly bound together with some insulating tape. Two binding-posts may then be fastened to the hoop and the terminals of the coil connected to them.Two such coils are required for a complete wireless telephone system, one to be located at each station.It is also necessary to make a double-contact strap-key. Such a key is easily built out of a few screws and some sheet-brass. The illustration shows the various parts and construction so clearly that no detailed explanation is necessary.Fig. 239.—A Double-Contact Strap-Key.Fig. 239.—A Double-Contact Strap-Key. The Dotted Lines show how the Binding-Posts are connected.The telephone transmitter and the telephone receiver required for this experiment must be very sensitive, and it is hardly possible for the young experimenter to build one which will be satisfactory. They can be secured from a second-hand telephone or purchased at an electrical supply house. The transmitter should be of the "long distance" type. An 80-ohm receiver will serve the purpose, but if you also have a wireless station, use the same 1000-ohm receivers belonging to your wireless set and you will secure very good results.A battery capable of delivering about 10 volts and a good constant current is required.The apparatus is connected as shown in Figure 240.When the key is pressed, the coil is connected to the battery and the telephone transmitter. If words are then spoken into the transmitter they will vary the amount of current flowing and the magnetic field which is set up in the neighborhood of the coil will induce currents in the coil at the other station, provided that it is not too far away, and cause the words to be reproduced in the telephone receiver.When the key is released it will connect with the upper contact and place the telephone receiver in the circuit for receiving, so that your chum at the other station can answer your message by pressing his key and talking into his transmitter.Fig. 240.—The Circuit of the Wireless Telephone.Fig. 240.—The Circuit of the Wireless Telephone. When the Key is up, the Receiver is ready for Action. When the Key is pressed, the Transmitter and Battery are thrown into the Circuit.The best plan is to mount each of the coils upon a tripod and experiment by placing them close together at first and gradually moving them apart until the maximum distance that the apparatus will work is discovered.Be very careful to keep the two coils exactly parallel.Much depends upon the battery. Be certain that it is capable of delivering a good strong current. Do not hold the key down any longer than is absolutely necessary, or the telephone transmitter will become hot.By making the coils six feet in diameter and placing from 200 to 400 turns of wire in each coil you can make a set which is capable of transmitting speech 300 feet or more.Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs.Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs. 1. The Telephone Coil. 2. The Telephone Transmitter. 3. Double-Contact Strap-Key. 4. The Battery. 5. Spark Coil. 6. Key. 7. Spark-Gap. 8. Aerial Switch. 9. Loose Coupler. 10. Detector, 11. Fixed Condenser. 12. Code Chart. 13. Amateur License. 14. Aerial. 15. Telephone Receivers.The coil may be mounted on the wall of your shop in a position where it will be parallel to one located in your chum’s house.The success of a wireless telephone system of this sort lies in making the coils of large diameter and many turns, in keeping the coils parallel, using a sensitive transmitter and receiver, and in employing a good strong battery. Storage cells are the best for the purpose.ELECTRIC MOTORS
Probably many readers of the "Boy Electrician" are amateur wireless operators and have constructed their own apparatus with which they are able to pick up commercial messages or communicate with other experimenters in the neighborhood, but not many have ever built a wireless telephone.
The device described in the following pages is easy to make and arrange, and will serve for some very interesting experiments.
It is of no practical value as a commercial wireless telephone, because the distance over which it will transmit speech is limited to from 250 to 300 feet. If you have a chum who lives across the street and within the distance named above, it is possible for you to construct a simple wireless telephone which will enable you to remain in your own rooms and talk to each other without any connecting wires.
The instruments operate by magnetic induction. It has already been explained how it is possible for the current in the primary of an induction coil to induce a current in the secondary coil, even though the two are not electrically connected. This type of wireless telephone really consists of an induction coil in which the two windings are widely separated.
Suppose that two coils of wire are connected as in Figure 237. The illustration shows that one coil,A, is connected in series with a set of batteries and a telegraph key. The terminals of the other coil,B, are connected to a telephone receiver. The coils are placed parallel to each other and a few inches apart. If the key is pressed so that the battery current may flow through the coil,A, it will create a magnetic field, and lines of force will be set up in the immediate vicinity. The lines of force will pass through the coil,B, and induce in it a current of electricity which will cause a sound like a click to be heard in the telephone receiver.
Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.
Fig. 237.—A Simple Arrangement showing the Inductive Action between two Coils.
If a telephone transmitter is substituted for the key and words are spoken into it, the current passing through the coil from the battery will vary with each vibration of the voice and the words will be distinctly repeated by the receiver connected toB.
This experiment may be tried by any boy with the equipment he probably has already around his shop. Twenty-five to thirty turns of wire wound around a cardboard tube five or six inches in diameter will serve as a coil. Two such coils, an ordinary telephone transmitter, a telephone receiver and a couple of dry cells are all that is required.
Fig. 238.—A Simple Wireless Telephone.Fig. 238.—A Simple Wireless Telephone. Speech directed into the Transmitter can be heard in the Receiver, although there is no direct electrical connection between the two.
Fig. 238.—A Simple Wireless Telephone. Speech directed into the Transmitter can be heard in the Receiver, although there is no direct electrical connection between the two.
The diagram in the accompanying illustration shows how the apparatus is arranged. The coils may be used several inches apart and the voice will be clearly heard in the receiver.
Such an outfit is, however, only experimental, and if it is desired to make a practical set, the coils, etc., must be much larger in diameter and contain a greater number of turns.
Larger coils are made by first drawing a circle four feet in diameter on the floor of the "shop" or attic. Then drive a number of small nails around the circumference, about four inches apart.
Procure two and one-half pounds of No. 20 B. & S. gauge cotton-covered magnet wire and wind it around the circumference of the circle. The wire should form at least sixty complete turns. About one foot should be left at each end to establish connections with. After winding, the coil should be tied about every six inches with a small piece of string so that it will retain its shape and not come apart. The nails are then pulled out so that the coil may be removed.
The coil may be used just as it is for experimental purposes, but if it is intended for any amount of handling it is wise to procure a large hoop such as girls use for rolling along the sidewalk, and make the coil the same diameter as the hoop so that upon completion they may be firmly bound together with some insulating tape. Two binding-posts may then be fastened to the hoop and the terminals of the coil connected to them.
Two such coils are required for a complete wireless telephone system, one to be located at each station.
It is also necessary to make a double-contact strap-key. Such a key is easily built out of a few screws and some sheet-brass. The illustration shows the various parts and construction so clearly that no detailed explanation is necessary.
Fig. 239.—A Double-Contact Strap-Key.Fig. 239.—A Double-Contact Strap-Key. The Dotted Lines show how the Binding-Posts are connected.
Fig. 239.—A Double-Contact Strap-Key. The Dotted Lines show how the Binding-Posts are connected.
The telephone transmitter and the telephone receiver required for this experiment must be very sensitive, and it is hardly possible for the young experimenter to build one which will be satisfactory. They can be secured from a second-hand telephone or purchased at an electrical supply house. The transmitter should be of the "long distance" type. An 80-ohm receiver will serve the purpose, but if you also have a wireless station, use the same 1000-ohm receivers belonging to your wireless set and you will secure very good results.
A battery capable of delivering about 10 volts and a good constant current is required.
The apparatus is connected as shown in Figure 240.
When the key is pressed, the coil is connected to the battery and the telephone transmitter. If words are then spoken into the transmitter they will vary the amount of current flowing and the magnetic field which is set up in the neighborhood of the coil will induce currents in the coil at the other station, provided that it is not too far away, and cause the words to be reproduced in the telephone receiver.
When the key is released it will connect with the upper contact and place the telephone receiver in the circuit for receiving, so that your chum at the other station can answer your message by pressing his key and talking into his transmitter.
Fig. 240.—The Circuit of the Wireless Telephone.Fig. 240.—The Circuit of the Wireless Telephone. When the Key is up, the Receiver is ready for Action. When the Key is pressed, the Transmitter and Battery are thrown into the Circuit.
Fig. 240.—The Circuit of the Wireless Telephone. When the Key is up, the Receiver is ready for Action. When the Key is pressed, the Transmitter and Battery are thrown into the Circuit.
The best plan is to mount each of the coils upon a tripod and experiment by placing them close together at first and gradually moving them apart until the maximum distance that the apparatus will work is discovered.
Be very careful to keep the two coils exactly parallel.
Much depends upon the battery. Be certain that it is capable of delivering a good strong current. Do not hold the key down any longer than is absolutely necessary, or the telephone transmitter will become hot.
By making the coils six feet in diameter and placing from 200 to 400 turns of wire in each coil you can make a set which is capable of transmitting speech 300 feet or more.
Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs.Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs. 1. The Telephone Coil. 2. The Telephone Transmitter. 3. Double-Contact Strap-Key. 4. The Battery. 5. Spark Coil. 6. Key. 7. Spark-Gap. 8. Aerial Switch. 9. Loose Coupler. 10. Detector, 11. Fixed Condenser. 12. Code Chart. 13. Amateur License. 14. Aerial. 15. Telephone Receivers.
Fig. 241.—A Complete Wireless Telephone and Telegraph Station for Amateurs. 1. The Telephone Coil. 2. The Telephone Transmitter. 3. Double-Contact Strap-Key. 4. The Battery. 5. Spark Coil. 6. Key. 7. Spark-Gap. 8. Aerial Switch. 9. Loose Coupler. 10. Detector, 11. Fixed Condenser. 12. Code Chart. 13. Amateur License. 14. Aerial. 15. Telephone Receivers.
The coil may be mounted on the wall of your shop in a position where it will be parallel to one located in your chum’s house.
The success of a wireless telephone system of this sort lies in making the coils of large diameter and many turns, in keeping the coils parallel, using a sensitive transmitter and receiver, and in employing a good strong battery. Storage cells are the best for the purpose.
ELECTRIC MOTORS