A phase-controlled power supply is disclosed. The power supply includes a power conditioner with an input configured to connect to an external source of electrical power, the power conditioner being configured to provide conditioned power on its output. The power supply also includes a transformer having a primary winding and a secondary winding, and a switching module coupled between the output of the power conditioner and to the primary winding of the transformer. The switching module has two modes of operation and a control signal input configured to accept a first control signal. The switching module includes a switching element configured to connect the power conditioner output to the primary winding of the transformer. The switching module operates in the first mode when the first control signal is in a first state, switching the first switching element at a first frequency and first duty cycle. The switching module operates in the second mode when the first control signal is in a second state, switching the first switching element at a frequency and duty cycle according to the first control signal.