Abstract: Disclosed examples include firing control electronic circuits, such as electronic ignition modules (EIMs), electronic detonators and firing circuits for blasting applications, in which a Zener diode or one or more general purpose diodes is connected between a firing capacitor and charging voltage source in a circuit with a detonator ignition element to block voltage below a certain desired level so that the firing capacitor is not charged to enhance safety in the logger mode.

Abstract: A method of calibrating a coefficient of a pressure sensor for blasting operations, including striking a first piezoelectric sensor of a first unmolded pressure sensing apparatus; determining, with an interface circuit, a first peak voltage of the first piezoelectric sensor during the striking thereof, striking a second piezoelectric sensor of a second molded pressure sensing apparatus; determining with the interface circuit, a second peak voltage of the second piezoelectric sensor during the striking thereof, and calculating a piezoelectric constant of the second piezoelectric from at least the first and second peak voltages.

Abstract: Disclosed examples include firing control electronic circuits, such as electronic ignition modules (EIMs), electronic detonators and firing circuits for blasting applications, in which a Zener diode or one or more general purpose diodes is connected between a firing capacitor and charging voltage source in a circuit with a detonator ignition element to block voltage below a certain desired level so that the firing capacitor is not charged to enhance safety in the logger mode.

Abstract: A method of calibrating a pressure sensing apparatus for measuring borehole pressure during blasting operations is provided. The method includes: striking a first piezoelectric sensor of a first unmolded pressure sensing apparatus; determining, with an interference circuit, a first peak voltage of the first piezoelectric sensor during the striking thereof; striking a second piezoelectric sensor of a second molded pressure sensing apparatus; determining with the interference circuit, a second peak voltage of the second piezoelectric sensor during the striking thereof; and calculating a piezoelectric constant of the first piezoelectric from at least the first and second peak voltages.

Abstract: Pressure sensors and techniques are presented in which one or more piezoelectric discs are housed in a holder structure with a hole allowing exposure of the piezoelectric disc(s) to ambient pressure within a borehole, with wiring leads passing through the holder structure for conveying an electrical signal from the piezoelectric device to an external interface circuit or for conveying an electrical signal from an internal interface circuit to an external data acquisition system.

Abstract: A signaling system (10) in the form of a dispatcher activated response identification system is provided for responding exclusively to a predefined signal transmitted from a first location through a telephone service line interconnected thereby with a telephone at a second location to assist responding personnel in identifying the second location when the predefined signal is transmitted from the first location. The signaling system includes first and second electronic circuits (40, 60) at the second location. The first electronic circuit is adapted to generate a first signal (58) at the second location in response to receiving the predefined signal transmitted through the telephone service line. The second electronic circuit is physically separated from the first electronic circuit and is preferably placed where it is easily visible from the street such as in a window.

Abstract: A fuse or ignition conductor for conducting ignition from an igniter to a remotely located primer, as used in the detonation of explosives. The ignition conductor contains a light transmitting fiber optic cord bound to the ignition conducting material of the fuse in such manner that if the ignition conducting material is broken, the fiber optic cord is also broken. The claimed subject matter further includes assemblies containing means at the primer end for transmitting light back to the igniter end.

Abstract: A continuity checking system for detonating cord having four principle parts. The detonating cord has a fiber optic cord associated therewith to run from the blasting cap to a remote primer; a light return device is installed at the primer; a disposable testing head is installed at the end of the detonating cord adjacent the blasting cap; and a testing device is positioned a safe distance away from the disposable testing head. The testing head utilizes an LED with means for illuminating the end of the fiber optic cord, and a light sensitive device with means for sensing return light from the fiber optic cord. An electrical input signal, and an electrical output signal from the disposable testing head is communicated by electrical wires to the remote testing device.

Abstract: An object of the present invention is the provision of a new and improved vehicle anti-theft device wherein electrical switches are located in the operator compartment of the vehicle and must be actuated in proper sequence to transmit simple make or break functions through wires leading to electronic circuitry that is located in a locked area, and which controls the ignition circuit. Additional code actuated circuitry is provided to permit authorized personnel, e.g. parking attendants, to operate the vehicle.

Abstract: A control circuit utilizing: a counter which provides first and second output signals at spaced apart time intervals and delay means for stopping and starting the counter; and switch means having start and stop inputs and an output connected to the delay means of the counter. The switch means, being arranged to start the counter when the start input is energized, and being arranged to stop the counter when the stop input is energized. The stop input of the switch means being actuated by the first counter output signal.

Abstract: A homing system utilizing a loop antenna positioned at approximately 45.degree. to the vertical to provide an electromagnetic field having both horizontal and vertical components. These signal components are picked up by a vertical loop stick antenna alternately connected to one of two bifilar wound coils of a horizontal loop stick antenna to provide alternating signals. The strength diagrams for the alternating signals are cardioid shaped and are arranged back to back with their null point passing through the intersections of the back to back signals. The null point of both antenna systems occurs when the horizontal loopstick antennas are at right angles to the electromagnetic lines of force; and any time that the horizontal loop sticks are turned at an angle relative to their null point, a difference in signal strength exists between the two antenna systems. This is picked up, and is amplified at separate time intervals by a common amplifier.

Abstract: A sequencing system for a series of control circuits; each of which has its own control switch. A signal of spaced apart pulses is communicated simultaneously to all control switches. Separate normally closed grounding switches are provided for all but the first of the series of control switches to make them inoperative. Each control circuit after the first is provided with a connection which opens its grounding switch in response to power flowing through the preceeding control circuit of the series.

Abstract: A blasting machine comprising a pulse generator which delivers its pulses to a control signal transmitting circuit that in turn delivers the pulses to driven blast initiating circuitry. The control signal transmitting circuit includes an electronic switch which is not only turned on and off by the pulse generator but is also turned off by a deactivating circuit when the voltage of a power supply for the machine is below a predetermined level. When the voltage of the power supply is above this predetermined level, the deactivating circuit is made inoperative so that it can no longer turn off the electronic switch.