| 摘要 |
A system for charging subscribers' batteries from a central telephone exchange without interference to normal telephone activity. During charging the subscriber's battery 4 is periodically disconnected from the line 3 by a switch 10 and line voltage sensed by a sensor 7 to ascertain whether a call is to be made or received. Line voltage equal to central battery voltage indicates non-use and causes line to be reconnected to subscriber's battery. Charging current pulse sensor 12 at exchange disconnects central battery 5 from line 3 on absence of charging pulses on the line or presence of ringing voltage on subscriber's exchange equipment 1. <IMAGE> |
