Control circuit for a detonator

A control circuit for a detonator which is configured to be connected to an end of a shock tube which, upon ignition, generates a shock tube event at an end of the shock tube, wherein the control circuit includes a fusible link which is mounted to be responsive to a first characteristic of a shock tube event, a sensor which is mounted to be responsive to a second characteristic of a shock tube event, an energy source at a first voltage level, a charge pump which is configured, when operative, to produce an output voltage at a second voltage level which is higher than the first voltage level, the charge pump including an inductor which is connected to earth by the fusible link, the control circuit further including a capacitor which is connected to the charge pump, a switch, and a logic unit, and wherein the fusible link, upon detecting said first characteristic, is fused and the connection of the inductor to earth is then open-circuited, and the logic unit, upon detection by the sensor of said second characteristic, places the charge pump in an operative mode whereby said output voltage is applied to the capacitor and, upon operation of the switch, the capacitor is caused to discharge through an ignition element of the detonator and so fire the detonator.