Timing and firing circuitry

Abstract

First and second ganged switches having first and second operative relationships are normally operative in the first relationship and are actuated by an external mechanism to the second relationship. In the first relationship, the first switch shunts and short circuits a pyrotechnic device and the second switch shunts and short circuits an energy storage member such as a capacitor. In the second operative relationship of the second switch, a battery charges the capacitor and also introduces a starting signal to an electronic timing circuit to institute a timing sequencer by the circuit for a pre-selected period that is selected via a series of inputs to the electronic timer. When the pre-selected time period has been timed out, the timing circuit introduces a signal to a solid state electronic switch which is normally in a non-conductive state to prevent actuation. The signal from the timing circuit causes the electronic switch to provide a low impedance. In the second operative relationship of the first and second switches, the capacitor discharges through a circuit including the second switch, the electronic switch, the capacitor and the pyrotechnic device. This discharge fires the pyrotechnic device.