Abstract: A punch press apparatus for perforating explosive sheet material has a cur plate containing multiple tubular cutters projecting below the plate. Each cutter contains a spring biased plunger for ejecting cutout sheet material from within the tubular cutter. The rearward end of each plunger projects above the cutter plate and contains a compression spring which returns the plunger to its original position after it has ejected the cutout material. A removable plunger protector plate is positioned above the cutter plate and a plunger ejector plate is located above the protector plate. The latter contains holes for receiving the projecting plunger ends so that the plungers are not depressed when the ejector plate is moved downward to press the protector plate onto the cutter plate to perforate the sheet material against an anvil. After the perforation operation, the protector plate is removed and the ejector plate is moved downward to depress the plungers which eject the cutout sheet material from the cutters.

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.