Classification of Sets

Telephones may be cla ified under two general headings, magneto telephones and common-battery telephones, according to the character of the systems in which they are adapted to work. Magneto Telephone. The term magneto telephone, as it was originally employed in telephony, referred to the type of instrument now known as a receiver, particularly when this was used also as a transmitter. As the use of this instrument as a transmitter has practically ceased, the term magneto telephone has lost its significance as applying to the receiver, and, since many telephones are equipped with magneto generators for calling purposes, the term magneto telephone has, by common consent, come to be used to designate any telephone including, as a part of its equipment, a magneto generator. Magneto telephones usually, also, include local batteries for furnishing the transmitter with current, and this has led to these telephones being frequently called local battery telephones. However, a local battery telephone is not nece arily a magneto telephone and vice versâ , since sometimes magneto telephones have no local batteries and sometimes local battery telephones have no magnetos. Nearly all of the telephones which are equipped with magneto generators are, however, also equipped with local batteries for talking purposes, and, therefore, the terms magneto telephone and local battery telephone usually refer to the same thing. Common-Battery Telephone. Common-battery telephones, on the other hand, are those which have no local battery and no magneto generator, all the current for both talking and signaling being furnished from a common source of current at the central office. Wall and Desk Telephones. Again we may cla ify telephones or telephone sets in accordance with the manner in which their various parts are a ociated with each other for use, regardle of what parts are contained in the set. We may refer to all sets adapted to be mounted on a wall or partition as wall telephones , and to all in which the receiver, transmitter, and hook are provided with a standard of their own to enable them to rest on any flat surface, such as a desk or table, as desk telephones . These latter are also referred to as portable telephones and as portable desk telephones. In general, magneto or local battery telephones differ from common-battery telephones in their component parts, the difference residing principally in the fact that the magneto telephone always has a magneto generator and usually a local battery, while the common-battery telephone has no local source of current whatever. On the other hand, the differences between wall telephones and desk telephones are principally structural, and obviously either of these types of telephones may be for common-battery or magneto work. The same component parts go to make up a desk telephone as a wall telephone, provided the two instruments are adapted for the same cla of service, but the difference between the two lies in the structural features by which these same parts are a ociated with each other and protected from exposure. IMG:384091999325875926_fig142_t.gif.png:Illustration_ Fig. 142. Magneto Wall Set Fig. 142. Magneto Wall Set View full size illustration. IMG:384091999325875926_fig143_t.gif.png:Illustration_ Fig. 143. Magneto Wall Set Fig. 143. Magneto Wall Set View full size illustration.