A two-wire load control device (such as, a dimmer switch) is operable to control the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) and has substantially no minimum load requirement. The load control device includes a bidirectional semiconductor switch (such as thyristor), which may be operable to remain conductive independent of the magnitude of a load current conducted through the thyristor and to conduct the load current to and from the load during a single half-cycle. The dimmer switch comprises a power supply that conducts a charging current through the load in order to generate a supply voltage. The dimmer switch comprises a control circuit that controls a gate coupling circuit for rendering the thyristor conductive each half-cycle. The control circuit may provide a constant gate drive to the thyristor after the thyristor is rendered conductive each half-cycle.