Telephones and Telephone Circuits
This is a means of transmitting speech over long distances by the use of electric conductors.
Simple Transmitter (See Figure 2 below)
1.The sound waves from the voice hits the diaphragm causing varying/changing amounts of pressure on the carbon grains.
2. Their overall resistance will vary according to these pressures, so that sound changes will be converted into resistance changes.
3.When a voltage is applied to the device a varying/changing current (a.c) is produced as its resistance changes.
Simple Receiver (See Figure 2 below)
1.When current in the coil varies, the magnetic force on the diaphragm will cause it to move. This movement sets up movements of the air thus converting the electric charges into sound waves.
More modern forms of telephones use crystal-type microphones and receivers. The use of relays and switches enables the same conductors between the hand-sets to be used for both ringing and speech circuits.
This is a means of transmitting speech over long distances by the use of electric conductors.
Simple Transmitter (See Figure 2 below)
1.The sound waves from the voice hits the diaphragm causing varying/changing amounts of pressure on the carbon grains.
2. Their overall resistance will vary according to these pressures, so that sound changes will be converted into resistance changes.
3.When a voltage is applied to the device a varying/changing current (a.c) is produced as its resistance changes.
Simple Receiver (See Figure 2 below)
1.When current in the coil varies, the magnetic force on the diaphragm will cause it to move. This movement sets up movements of the air thus converting the electric charges into sound waves.
More modern forms of telephones use crystal-type microphones and receivers. The use of relays and switches enables the same conductors between the hand-sets to be used for both ringing and speech circuits.
Creating Your Own Telephone Network