A device comprising: a power supply; a first light emitting device (111a, 111b, 111c, 111d) for generating light of a first color; and a boost converter having an input node electrically coupled to the power supply and having an output node, with the first light emitting device (111a, 111b, 111c, 111d) electrically coupled between the output node and a first reference node to receive a continuous electrical current from the boost converter, wherein the boost converter comprises, a switch electrically coupled in a current shunting path between the input node and the first reference node, wherein the switch is configured to shunt current from the power supply around the first light emitting device (111a, 111b, 111c, 111d), and a controller configured to generate a pulse width modulation signal to control a duty cycle of the switch to provide a pulse width modulated, PWM, electrical current through the switch and the continuous electrical current through the first light emitting device (111a, 111b, 111c, 111d); and characterised by a second light emitting device (121a, 121b, 121c) for generating light of a second color, different to the first color, electrically coupled between the input node and the power supply and/or between the first reference node and a second reference node, so that a current through the second light emitting device (121a, 121b, 121c) is equal to a sum of the pulse width modulated electrical current through the switch and the continuous electrical current through the first light emitting device (111a, 111b, 111c, 111d). a power supply; a first light emitting device (111a, 111b, 111c, 111d) for generating light of a first color; and a boost converter having an input node electrically coupled to the power supply and having an output node, with the first light emitting device (111a, 111b, 111c, 111d) electrically coupled between the output node and a first reference node to receive a continuous electrical current from the boost converter, wherein the boost converter comprises, a switch electrically coupled in a current shunting path between the input node and the first reference node, wherein the switch is configured to shunt current from the power supply around the first light emitting device (111a, 111b, 111c, 111d), and a controller configured to generate a pulse width modulation signal to control a duty cycle of the switch to provide a pulse width modulated, PWM, electrical current through the switch and the continuous electrical current through the first light emitting device (111a, 111b, 111c, 111d); and a switch electrically coupled in a current shunting path between the input node and the first reference node, wherein the switch is configured to shunt current from the power supply around the first light emitting device (111a, 111b, 111c, 111d), and a controller configured to generate a pulse width modulation signal to control a duty cycle of the switch to provide a pulse width modulated, PWM, electrical current through the switch and the continuous electrical current through the first light emitting device (111a, 111b, 111c, 111d); and characterised by a second light emitting device (121a, 121b, 121c) for generating light of a second color, different to the first color, electrically coupled between the input node and the power supply and/or between the first reference node and a second reference node, so that a current through the second light emitting device (121a, 121b, 121c) is equal to a sum of the pulse width modulated electrical current through the switch and the continuous electrical current through the first light emitting device (111a, 111b, 111c, 111d).