Burglar alarms, rescue equipment and electric fences


During the recession of the 1930s, demand for telephone equipment fell dramatically. To keep the production plants running, Ericsson broadened its product range. And broad was definitely the word. If anything could be manufactured with existing equipment and personnel, Ericsson was interested in trying it.

There were many examples of unusual products that bore the Ericsson name during this time.

The photo-electric burglar alarm: In 1934, F von Meissner published an article in Ericsson Review that Ericsson had developed. The introduction to the article contained the following enthusiastic description: "The new Ericsson burglar-alarm system with photo-electric cells is described below. At the present stage of technical development it constitutes the best automatic protection again burglary for apartments or whole buildings. Banks, offices where money or other valuables are kept, museums, libraries, shops - especially jewelers - factories, private houses with extensive grounds, etc. are by the Ericsson photo-electric system provided with a means of protection against burglary that even the most scientific burglar is incapable of avoiding or rendering harmless."

This for the time very modern system worked as follows. A small projector cast a ray of light on a light-sensitive cell, which in turn was connected to a power circuit. The cell carried current to the circuit only as long as it was subject to light. It the ray of light was broken, if even for a moment, the current stopped flowing and an alarm sounded. A filter could also be used to make the ray of light invisible.

Among the sales arguments advanced for the burglar alarm, one of the strongest was that maintenance costs for the system were extremely low. Trained personnel for monitoring and service were also not required.

Mine rescue telephones One of the earliest and most important of Ericsson's foreign subsidiaries was the British company Ericsson Telephones Ltd. Because Great Britain had a large and important mining industry well into the 1900s, it was perhaps not surprising that the Ericsson subsidiary together with the Mines Department Testing Station developed a telephone for mine rescue operations that was approved in 1938.

The system consisted of two parts, a base station and a moveable station linked by a cable. Because rescue personnel going down into a mine wore breathing masks and therefore could not speak on the telephone, they communicated with the base station using signals. From the base station, however, it was possible to transmit both voice and signals to the moveable station.

Electric fences The accompanying image shows an electric cattle fence made by Ericsson. Production probably started in the parent company in the 1930s. After the end of World War II, however, production was transferred to the newly established subsidiary AB Ermex, which also took over lock manufacturing. During the 1960s, Ericsson's resources were concentrated to core business areas, and Ermex was therefore sold in 1963.

Author: Pontus Staunstrup


The board approves the founding of a British subsidiary, The British L.M. Ericsson Manufacturing Company Ltd, at Beeston.


Central component of thief alarm system with infrared beams and cables.

© Telefonaktiebolaget LM Ericsson and Centre for Business History

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