Abstract: A circuit having indication lights for demonstrating when a flash trigger pulse has been fed to an X-ray photographic system or the like, is provided. The invention is especially useful in noting that a false triggering pulse, or prefire had inadvertently happened to a flash unit of an X-ray system before it was intended to be used, thus triggering it to photograph, ruining its film. This invention is also useful in that it marks which in a plurality of systems had been the one that had been falsely triggered, and additionally useful in marking that all of the said units had been properly triggered when a true pulsing had been engaged for all units, or of marking which unit had failed to fire.