Abstract: A power supply circuit for powering components of a facility are disclosed. The power supply circuit may include a power transformer, a power input terminal, a power output terminal, a bridge, a relay, and a control circuit. The relay is connected between the power input terminal and the power output terminal. A primary side of the power transformer is coupled between the relay and the power output terminal. The bridge is coupled to the secondary side of the power transformer. In a normal power mode, the control circuit closes the relay and operates the bridge as a rectifier. In an emergency power mode, the control circuit opens the relay and operates the bridge as a pulse width modulator. In this manner, the bridge and the power transformer can be used both to charge a battery during normal operation and generate emergency AC power from the battery.

Abstract: An elevator cab includes primary and auxiliary light sources. A light sensor responsive to light from the primary light source causes activation of the auxiliary light source when the primary light source fails. The light sources are inside the cab for passenger use and/or outside the cab for maintenance worker use. A battery for auxiliary light is selectively charged by first and second current levels in response to the battery voltage being above or below first or second different thresholds.