Artist: Lars Magnus Ericsson
Date: 1900
Size: 135 x 57 cm
Museum: Fundação Portuguesa das Comunicações (Lisbon, Portugal)
Technique: Plastic
An Ericsson TEL. A.B. manual switchboard with ten phone lines and fifty possible extensions (secondary switchboards) for manual telephone communications between subscribers. The bottom of the structure consists of a sewing machine base on which lies a square wooden table. Towards the back of this stands an upright rectangular wooden structure. On the front of this, at the top, there is a set of jack sockets numbered from 1 to 50 that are protected by individuals covers which drop whenever the extension corresponding to the particular number is activated. Lower down the front of this same structure are fifty jacks numbered from 1 to 50 into which the plugs of the phone cords are inserted. There are also another 10 jacks numbered from 1 to 10 below these protected with a removable cover, and corresponding to each of the ten lines in the network, which drop whenever any of the lines are activated. At each end of this line of 10 jacks are two buttons with the letters “U” and “MI” written on them for the specific activation of communication. On the left is a metal rest for the microtelephone. At the back is a removable wooden cover with a lock for access to the inside to check or repair any of the electrical connections. On the cover of this is a brief schematic of the switchboard’s functional connections. On the nearest part of the table, laid out horizontally, are ten jacks into which the phone cord plugs are inserted; and also a set of ten horizontally moving switches to connect and disconnect each of the network’s ten phone lines, as well as three similar switches for placing in-coming calls on hold identified by the letters “T”, “I” and “B”. At the front of the table, on the right, there is a crank handle with a magneto which, when wound, creates the necessary induction voltage to establish communication with the outside or with any of the extensions. On the left is the input/fixing point for the microtelephone cable. At the back of the table is a set of metal terminals to attach the necessary phone conductors. Suspended from the underside of the table with weights are ten phone cords corresponding to the number of lines in the network, as well as the outlet for two telephone cables (with four conductors each) for connection to the public phone network
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