Abstract: Detonator apparatus, such as a blasting machine detonator, is provided with a miniature transformer having multi-turn primary and secondary coils. The transformer feeds a bridge wire detonator element, and has sufficient impedance to permit impedance matching with a carrier that may be as long as 7500 m. The impedance of the detonator is such that the detonator resists firing when subject to stray currents or commonly present power or communications signals. A blasting machine is provided that is specifically designed to provide a signal having a frequency in the range in which the detonator is sensitive. The blasting machine relies upon semi-conductor switching and timing circuits to control the discharge from a pair of capacitors, rather than upon an output transformer.

Abstract: Shaped charge assembly for use as part of a perforating gun, particularly, channel finder gun. The shaped charge assembly includes a charge is configured to produce a jet which is substantially non-circular in cross section (in relation to the axial direction of travel of the jet) in which the assembly includes a base that is relatively rigid with respect to the liner of the assembly.

Abstract: This invention provides a method and electronic circuits for the testing of new initiation devices that use a small transformer whose heating element resistance can not be measured using traditional methods and instruments. A small current testing signal is applied to the primary winding of the detonator through its leg wires that are connected in a certain circuit configuration. The resistance of the secondary winding connected with the bridge wire is then reflected to the primary side and its effects are then observed. By calibrating the relationship of such effects with the value of loop resistance, the loop resistance can he displayed. Since the testing signal is very small in nature for safety considerations, the sampled effects (generally the voltage wave) are amplified. The amplified effects are displayed with analogue or digital meters or other display means.

Abstract: An apparatus for manufacturing a machined article from an elongated tubular workpiece is disclosed. A machining device is movable within a work area of the apparatus and a movable base having first and second spaced apart clamps secure a section of the article. A stationary third clamp is mounted independent of the movable base for holding the article in a stationary position relative to the movable base. A conveyor permits positioning of the article relative to the clamps.