Abstract: A control circuit for firing an electrically actuable igniter in response to a firing signal having predetermined characteristics. For protection from inadvertent or accidental actuation, the control circuit includes at least one inductor in series with the fuse wire of the igniter and at least one inductor in parallel with the source of the firing signal. The series and parallel inductors are electromagnetically coupled to one another through a ferrite bead and are electrically connected so as to generate opposed magnetic effects when current flows through them. Electric detonators incorporating the control circuit are also detailed.

Abstract: An ignition system for the firing of a plurality of electrically actuable igniters (16) and methods for construction and use of the assembly. The ignition leading wire (17) of each electrically actuable igniter (16) is formed from a continuous length of insulated wire connecting its two electrical connection terminals. The leading wire is looped around a transformer core (14) having a movable portion (15) that is opened to admit the loop. A firing cable (12) coupled to a source of electrical firing energy (11) is also looped around the transformer core completing the formation of a transformer for coupling electrical firing energy from the source to each of the igniters to be fired. A plurality of transformer cores can be coupled to a single firing energy source by looping a continuous wire from the source, through each transformer and then back to the source, thereby electromagnetically coupling firing energy to each transformer.