A POWER ADAPTOR FOR A LIGHTING SYSTEM AND OTHER IMPROVEMENTS TO LIGHTING SYSTEMS

摘要

There are described power adaptors for powering an LED from mains source. The power adaptors are arranged to provide compatibility with dimmers whilst avoiding use magnetic components such as inductors. The power adaptors include a non-magnetic current limiter e.g. a linear current regulator, arranged in series with the power adaptor's output, and means to limit the power dissipated through the current limiter as the input voltage increase. This ensures the current limiter does not overheat. The current limiting means may be switched off when the input voltage is significantly above a forward voltage of the LED. The power adaptor may include a switched capacitive voltage converter arranged to reduce the voltage drop across the current limiter as the input voltage increases, whilst ensuring the current limiter still draw current. The power controller also includes a switch arranged across the output that is switched on when the input voltage is below the forward voltage of the LED so that the power adaptor, and thus a dimmer connected in the lighting circuit, continues to draw current to power the dimmer's controller.