Telephone, Chemical.
A telephone utilizing chemical or electrolytic action in transmitting or
receiving. The electro-motograph is an example of a chemical receiver.
(See Electro-motograph.)
Telephone, Electrostatic.
A telephone utilizing electrostatic disturbances for reproduction of the
voice. In the cut D and C are highly charged electrophori. The
diaphragms A and B when spoken to affect the potential of the
electrophorus so as to produce current variations which will reproduce
the sound. Dolbear and others have invented other forms of transmitters
based on electrostatic action. Receivers have also been constructed. A
simple condenser may be made to reproduce sound by being connected with
a powerful telephone current.
Fig. 329. DIAGRAM OF EDISON'S ELECTROSTATIC TELEPHONE.
Telephone Induction Coil.
The induction coil used in telephone circuits for inducing current on
the main line. It is simply a small coil wound with two separate
circuits of insulated wire. In the Edison telephone the primary coil, in
circuit with the transmitter, is of No. 18 to 24 wire and of 3 to 4 ohms
resistance. The secondary in circuit with the line and receiving
instrument is of No. 36 wire and of 250 ohms resistance. The Bell
telephone induction coil has its primary of No. 18 to 24 wire wound to a
resistance of 1/2 ohm, and its secondary of No. 36 wire, and of 80 ohms
resistance.