CARE OF TELEPHONES

Evening Post, Volume CVII, Issue 146, 21 June 1924, Page 22

CARE OF TELEPHONES

Although, telephone receivers are apparently very sturdy pieces of apparatus, they need careful treatment, and are easily damaged. Special care should be taken not to drop them. This may result in dtrch damage as cracked cases or ear-pieces, and this will usually mean that the adjustment of the diaphragm »s impaired. It also results in weakening to some extent the permanent magnets, which are an important part, and this reduces the sensitiveness of the instruments. The diaphragms of the ordinary type 01' telephones should be perfectly flat, and if they' are dented or bent, new ones should be obtained. When the phones are worn for some time, a good deal of moisture condenses on the diaphragms. This should be lightly dried off with a bit of soft cloth or blotting-paper, but it is not necessary to unscrew the cap to do so. Some diaphragms become rusty. If this occurs, or in order to prevent it, take the diaphragms out and give them a very thin coat of varnish or of paraffin wax. The wax is highly satisfactory, and can be applied by putting the diaphragm on a plate heated to about the temperature of boiling water, and rubbing a piece of solid wax over the surface.

When telephones are used in connection with, a valve set, care- should be taken to have the B battery current go through them the right way. In most types of telephone one of the cords is marked either with a plus sign it with a red thread. This should be connected towards the battery. The reverse connection results in the steady current from the battery magnetising the soft-arm pole-pieces in opposition to the permanent magnets, which will thus be weakened. If the tip is not marked, the right end can be found with a little care. Remove a diaphragm and, by connecting a battery to the telephone both ways, see which connection increases the pull of the magnet. That is the correct .direction for the current, and the tip leading to the positive pole of the -battery should be marked.' If the telephones are not in a battery current the distinction betwen the cord tips is unimportant.