Telephone call timer comprising sand-filled hour-glass - has timing interval corresponding to telephone tariff period
Номер патента: DE3000570A1
Опубликовано: 16-07-1981
Автор(ы): Gerhard von 2104 Hamburg Glischinski
Принадлежит: Individual
Опубликовано: 16-07-1981
Автор(ы): Gerhard von 2104 Hamburg Glischinski
Принадлежит: Individual
Реферат: The timer comprises a transparent container divided into two compartments by a narrow restriction through which the sand passes. The size of this restriction and the amount of sand held in the container is such that it all passes from one compartment into the other in between 7 and 7 1/2 minutes, corresp. to the call tariff period for the German telephone network. The timer allows a subscriber to terminate a call before the elapse of the tariff period, so that a following tariff period which is not fully used is not paid for and the size of the telephone bill is thus reduced.
Time interval indicating device
Номер патента: US20120033532A1. Автор: Gayle E. Gordon,Ng Kwok-ho Victor. Владелец: Learning Resources Inc. Дата публикации: 2012-02-09.