Abstract: A detonator system wherein a detonator is connected via a down-hole harness to a bus extending from a blast controller and wherein a component is connected in series with the down-hole harness to limit leakage current in the harness to a level which can be accommodated by the blast controller.

Abstract: A detonator roll call method wherein each detonator is assigned a unique identifier and, at each detonator, in response to an enquiry signal to all the detonators a count is incremented and compared to the roll call identifier and, if the comparison is positive, a reply is sent by the detonator.

Abstract: A detonator roll call method wherein each detonator is assigned a unique identifier and, at each detonator, in response to an enquiry signal to all the detonators a count is incremented and compared to the roll call identifier and, if the comparison is positive, a reply is sent by the detonator.

Abstract: A detonator system (10) which has a plurality of segments (16), each segment having a respective plurality of detonators (14), and a synchronizer (18, 12), which may be a compound arrangement or a single device, which prevents the transmission of voltage modulated signals to the detonators (14) in one segment (16A) if current modulated segments are being transmitted from the detonators (14) in another segment (16B).

Abstract: The invention provides a blasting system which includes a plurality of electronic detonators which are configured in a blast array which has at least one row and a plurality of detonators in the row, each detonator including a memory in which is stored at least a respective identity code which is dependent, at least, on the row on which the detonator is, and on the detonator's position in the row, a harness which interconnects the detonators, and at least one control unit, connected to the harness, which generates a signal to fire the detonators.

Abstract: A detonator system which includes an array of a plurality of discrete time delay relays (16) connected in series to one another, and a plurality of detonators (28) which are respectively connected to the array at spaced intervals (22).

Abstract: The invention provides a blasting system which includes a plurality of electronic detonators which are configured in a blast array which has at least one row and a plurality of detonators in the row, each detonator including a memory in which is stored at least a respective identity code which is dependent, at least, on the row on which the detonator is, and on the detonator's position in the row, a harness which interconnects the detonators, and at least one control unit, connected to the harness, which generates a signal to fire the detonators.

Abstract: A detonator system (10) which has a plurality of segments (16), each segment having a respective plurality of detonators (14), and a synchroniser (18, 12), which may be a compound arrangement or a single device, which prevents the transmission of voltage modulated signals to the detonators (14) in one segment (16A) if current modulated segments are being transmitted from the detonators (14) in another segment (16B).