A control circuit configured for controlling current through a load, the control circuit comprising: a first terminal configured for connection to an alternating voltage source; a second terminal configured for connection to the load; a thyristor-type device connected between the first and second terminals and having a gate terminal; voltage regulation means configured for converting alternating voltage into a direct voltage, wherein the voltage regulation means is connected between the first and second terminals in parallel with the thyristor-type device; and gate current supplying means operable to supply current to the gate of the thyristor-type device, the gate current supplying means being powered by the voltage regulation means and including a variable input device operable to vary a first voltage waveform at the gate of the thyristor-type device in order to vary an output voltage waveform provided at the second terminal, characterised in that the gate current supplying means is arranged to supply, within a first half-cycle of an alternating voltage applied to the first terminal, the first voltage waveform at the gate of the thyristor-type device to supply a gate current to place the thyristor-type device in a conducting state followed by a second voltage waveform to supply a gate current to maintain the thyristor-type device in a conducting state, wherein: the first and/or the second voltage waveform (25, 29) is a sequence of pulses of the same magnitude; OR the second voltage waveform has a lower magnitude, absolute magnitude or average magnitude to that of the first voltage waveform. a first terminal configured for connection to an alternating voltage source; a second terminal configured for connection to the load; a thyristor-type device connected between the first and second terminals and having a gate terminal; voltage regulation means configured for converting alternating voltage into a direct voltage, wherein the voltage regulation means is connected between the first and second terminals in parallel with the thyristor-type device; and gate current supplying means operable to supply current to the gate of the thyristor-type device, the gate current supplying means being powered by the voltage regulation means and including a variable input device operable to vary a first voltage waveform at the gate of the thyristor-type device in order to vary an output voltage waveform provided at the second terminal, characterised in that the gate current supplying means is arranged to supply, within a first half-cycle of an alternating voltage applied to the first terminal, the first voltage waveform at the gate of the thyristor-type device to supply a gate current to place the thyristor-type device in a conducting state followed by a second voltage waveform to supply a gate current to maintain the thyristor-type device in a conducting state, wherein: the first and/or the second voltage waveform (25, 29) is a sequence of pulses of the same magnitude; OR the second voltage waveform has a lower magnitude, absolute magnitude or average magnitude to that of the first voltage waveform. the first and/or the second voltage waveform (25, 29) is a sequence of pulses of the same magnitude; OR the second voltage waveform has a lower magnitude, absolute magnitude or average magnitude to that of the first voltage waveform.