Photographic lightning trigger devices

Abstract

A method and device for detecting and photographing unregulated light flash events such as lighting strikes during both daylight and night time conditions is disclosed by detecting the initiation of the lightning stepped leader event of the immediate lightning flash for photographic and detecting activities. The present device utilizes a photodiode sensor in conjunction with a photoresistor to control feedback gain of a transimpedance amplifier to detect an unregulated, omni-directional flash of light and produces an output signal that is input to an analog comparator circuit where a predetermined threshold level is set to prevent false triggering of the isolation relay(s) and/or camera shutter. The output from the comparator circuit is input to a timer circuit to produce a signal of sufficient duration to trigger the isolation relay(s) and/or camera shutter. The output signal from the timer circuit is sent to isolation relays and/or an infrared coded pulse generator depending on the features of the particular camera in order to release the camera shutter or to protect an electronic or electrical device from the damaging effects of the lightning return stroke. In an alternative embodiment the functions of the comparator circuit, the timer circuit and the coded pulse generator are carried out by a programmable logic device such as a mixed signal processor with analog, digital, real time clock and non-volatile RAM capability wherein the lightning event processing functions are incorporated into the program code. The device circuitry is incorporated into a compact enclosure which can be mounted directly onto the camera or, or in the alternative integrated into the camera housing.