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Magneto telephone with special protection against high tension currents

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AB 5000
FRAMEWORK. Polished walnut, lined on the inside with tinned steel plates, which are connected to the earth terminal.

DUMMY MICRO-TELEPHONE. Suspended on a hook-switch.

The transmitter and receiver are enclosed in the case, the sound being carried by means of two vulcanised rubber tubes to the dummy micro-telephone.

The length of the rubber tubes is 39 inches.

GENERATOR. RH 5200, 5-magnet, which rings satisfactorily through a line resistance of 25,000 ohms.

RINGER. The resistance of the coils is 2000 ohms.

BATTERY. Two dry cells, RK 240 (Old No. 596).

PROTECTOR. This telephone is fitted with a carbon protector for one metallic line, which consists of :-

2 Carbons, SA 300.
2 Mica Insulators, SA 1 000.
2 Heat Coils, SC 10 (Old No. 703).

All exposed metal parts are insulated, the generator crank being made of ebonite and the hook-switch is also insulated from the frame by means of ebonite.

This telephone is specially designed for use in laces where there is any risk of the telephone lines being brought into contact with lines carrying high tension currents.

21.7 x 15.0 x 7.5 inches.

Weight: 38.5 lbs.

Telephone AB 5000 should be protected by using a double pole fuse, SD 50 (Old No. 748), which consists of two fuses, SB 100, mounted on a marble base, and provided with an enamelled iron cover. The latter is connected to the earth terminal.

Overall dimensions of mounted fuses, SD 50: 15.95 x 5.70 x 4.53 inches.

Weight: 7.7 lbs.

Originally numbered as the Model No. 445.

See also N2950.


Taken from the Ericsson Telephone Catalogues 1912 and 1923

Click here for an Ericsson Bulletin article on high voltage telephone lines

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Last revised: April 24, 2024