SLOT TELEPHONES

Otago Daily Times, Issue 23220, 18 June 1937, Page 16

SLOT TELEPHONES

THREE MINUTES FOR A PENNY The Post Office has almost completed the equipment of slot telephones with a timing device imposing a three-minute limit on the length of a conversation for a penny. To continue beyond three minutes involves payment of another penny, and this is operating effectively in restricting indefinitely long chats which may prevent the use of public call offices for urgent messages. Except for the clockwork mechanism, every part of this device is manufactured in the department's workshops, and it Was designed by its officers. Dropping in a penny to' open a conversation" trips a catch setting the clockwork in motion. It can be heard ticking away quietly until just before the end of three minutes, when a mild buzzing reminds the caller that further payment will be necessary if the conversation is to continue. There is no limit on the use of the slot telephone, but every three minutes has to be paid for.

Over 800 timing devices have been fitted to existing public call telephones operating through automatic exchanges, and'there is no need for this ingenious mechanism in connection with manually controlled exchanges because the operator checks tlfe duration of a call. A similar time checking system has been designed by the department for use in three-penny slot telephones. A rather difficult problem was presented by the fact that the threepenny bit is too light to operate any device with certainty. This problem has, however, been solved by reinforcing through electrical means the delicate pressure exerted by the weight of th<* coin. _____»_—