Abstract: Circuitry for driving an LED light source (100) from a mains supply (10) is shown. Before reaching the driver circuit (40) for LED (100), the mains supply (10) passes via a TRIAC dimmer (20) and a rectifier (30). The TRIAC dimmer (20) may comprise a dimmer switch in series with a TRIAC. The rectifier (30) is provided to convert the AC mains supply (10) to DC. The driver circuit (40), comprises a load switch (41) for controlling the driving of the LED (100), a ballast switch (42) for controlling the driving of a ballast resistance (43) and oscillator/driver (44) for controlling the load switch (41) and ballast switch (42). The oscillator (44) enables the LED (100) to be driven in a constant or pulsed manner and the ballast (43) to be driven in a pulsed manner. The pulsed current can be utilized to ensure that the TRIAC does not shut down when there is a low throughput of power, unlike the situation wherein an equivalent power is drawn via a steady state current of less than the TRIAC threshold current.