VOLUME CONTROL CIRCUIT FOR USE IN PORTABLE TELEPHONE OR THE LIKE

摘要

A volume control circuit for a portable telephone set having two volume setting circuits. One of these circuits is activated when the telephone is used within a vehicle and the other is activated when the telephone is removed from the vehicle and carried about as a personal telephone. One embodiment selects between these two circuits by operating mechanical structures which are moved between two positions by physically attaching or removing the telephone to or from the vehicle. Another embodiment uses a microprocessor to make the selection responsive to the operation of a magnetically actuated reed switch.