Abstract: An electronic delay blasting cap (10) receives an input signal over leg wires (12, 14). The input signal is passed through a rectifier (16) to produce a D.C. signal on output lines (26, 28). The D.C. signal charges a storage capacitor (32). When the input signal is removed or the wires (12, 14) are opened or shorted, the charge storage capacitor (32) discharges through a resistor (36) to produce a voltage which charges a timing capacitor (38). When the voltage on capacitor (38) reaches the threshold voltage of a zener diode (48) the diode is rendered conductive which in turn activates an SCR (46). A resistive ignition element (44) is connected in series with the SCR (46) and the charge storage capacitor (32) and is ignited when the SCR (46) is turned on. The charge stored in capacitor (32) causes ignition of the ignition element (44).

Abstract: A method and device for the initiating of a number of electrical detonators by a blasting machine of the type in which a capacitor is charged, the level of the charge being measured by level-sensing units and detonators are initiating by the electrical energy stored in the capacitor by firing after the charge level has reached a given level. The charge level of the capacitor is limited to a range which takes into account the variations of the load between different initiation moments such that the current impulse provided to each detonator assumes a value between a minimum and maximum limit. The limits for each individual load within the operating range of the apparatus is regulated in accordance with the electrical and physical characteristics of the detonators so that safe initiation and a disburance-free firing process are obtained.

Abstract: The specification discloses a hand-held detonator or blasting device which includes a rigid housing dimensioned to be held in the hand of an operator. A pair of binding posts extend from the housing for attachment to an explosive charge. First and second switches are mounted on the housing and a battery and capacitor are disposed within the housing. An oscillator is provided for being connected to the battery in response to operation of the first switch to generate an A.C. signal. A transformer is connected to the output of the oscillator to apply the A.C. signal to full-wave rectifying circuitry which produces a D.C. signal in order to charge the capacitor to a predetermined voltage level. Circuitry is responsive to operation of the second switch to disconnect the capacitor from the battery and to connect the capacitor across the binding posts in order to discharge the voltage stored thereon to detonate the explosive charge.

Abstract: A water activated pressurized gas release device, especially suited for automatically controlling the release of the pressurized gas for inflating flotation equipment when dumped into water, which includes an electrically fireable primer for generating propulsion gas to drive a piercing pin into the closure of a container of pressurized gas to release the same, and fired by electrical energy derived from a battery arranged in a circuit maintained open on the ground side by electrically conductive elements providing two spaced apart electrodes until such space is filled with water for a predetermined duration of time as occurs upon immersion to close the circuit.

Abstract: A release apparatus, for example for releasing fire extinguishant, comprises an electrically-rupturable link such as, for example, an electrically-fired detonator; and a circuit responsive to a voltage applied to the apparatus to charge electrical energy storage means, such as a capacitor, while the applied voltage is in one state and at least partially to discharge the stored energy into the link to rupture the link when the applied voltage changes to another state, such as reversed polarity.