An explosives detonator system (10) comprises a detonator housing (13) within which is provided a detonation circuit (17) that comprises a conductive pathway (16) having a fuse head (14) integrated therewith such that the conductive pathway (16) passes along both electrodes and a resistive bridge of the fuse head (14). An uncharged chargeable voltage source (12) is also integrated with the detonation circuit (17) and is electrically sensitive to a charging property which is included in a charging signal. Exposure to the charging property charges the voltage source (12), thereby rendering it capable of generating a potential difference between the electrodes at least to equal the breakdown voltage of the resistive bridge. The charging property is any one or more of a charging light pulse, a charging temperature, a charging pressure and a charging radio frequency.
