Abstract: An amplifier including a difference amplifier, said difference amplifier including a first output and a second output which are adapted for providing a PWM signal output to a load by signal difference between said first and said second outputs, said difference amplifier being adapted for operating in at least first and second alternative operating modes which are respectively characterised by first and second operating voltages, wherein during transition from one operating mode to another, the pulse area of the pulses of said first and second outputs of said difference amplifier are changed according to a pre-determined manner so that the pulse area of pulses of said first and second outputs at the end of said transitional mode is equivalent to the pulse area of the pulses of said first and second outputs immediately after the change of operating modes.

Abstract: A battery charger comprising an AC power input, isolation switching means, isolation control means, battery charging circuitry and battery receptacle, said isolation switching means substantially isolates said battery charging circuitry from said AC power input unless and until actuated by said isolation control means, said isolation switching means connects said battery charging circuitry to said AC power input for battery charging when actuated, wherein the operation of said isolation switching means being linked to the state of electrical insulation of said battery charging circuitry, said isolation control means and said isolation switching means being cooperatively configured so that said isolation switching means is actuated when said battery charging circuitry is electrically insulated from a user and said isolation switching means is caused to isolate said battery charging circuitry and said AC power input when said battery charging circuitry is not electrically insulated from a user.

Abstract: A fast battery charger in which each one of the battery charging sections comprises a charging branch and a bypassing branch, the battery charger is provided with enhanced charging monitory and control circuitry and method for performance elevation with minimal additional hardware overhead.