Apparatus for the control of self-propelled gamma-flaw detector

In a device for the radiographic testing of weld joints in a pipeline, including a normally deactivated radiation emitter trainable upon a weld joint, a self-propelled carrier for said radiation emitter, and propulsion means on said carrier for driving same inside a pipeline to be inspected,

• the combination therewith of equipment aboard said carrier comprising:
• sensing means responsive to external radiation transmitted through the pipeline wall;
• memory means adapted to assume several different states, including a quiescent state and at least one operational state, and connected to said sensing means for switchover from one state to another by command pulses of said external radiation;
• a first signal channel jointly controlled by said memory means for activating said radiation emitter in response to a command pulse of predetermined minimum duration in a de-energized condition of said propulsion means;
• a second signal channel controlled by said memory means for de-energizing and energizing said propulsion means in said quiescent state and said operational state, respectively, of said memory means;
• pulse-width-discriminating means in said first signal channel for making same nonresponsive to command pulses of less than said minimum duration, said pulse-width-discriminating means including a logical coincidence circuit with a pair of parallel inputs and delay means in series with one of said parallel inputs;
• and
• timing means connected between said first signal channel and said memory means for switching the latter to deactivate said radiation emitter after a predetermined irradiation period.