GB814805A - Improvements in and relating to igniters for explosives - Google Patents

Abstract

814,805. Electric blasting igniters. DYNAMIT - ACTIEN - GESELLSCHAFT VORM, A. NOBEL & CO. Aug. 9, 1955 [Dec. 24, 1954], No. 22934/55. Class 9(1) An electric detonator adapted to be fired by high frequency energy from a portable transmitter, more particularly by ultrashort waves, comprises a sheet metal or pasteboard casing enclosing a matchhead 1, a primary charge 4 and a base charge 5. The stopper surrounds leads 2a of a dipole receiver 2, the leads being connected by a filament within the match-head 1. A delay element 6 may be incorporated between the match-head and the charge 4. The transmitter may radiate either a single predetermined frequency or a plurality of predetermined frequencies whereby groups of detonators responsive to different energies or frequencies may be fired in succession. The same effect may be achieved by polarizing the signals transmitted for the different groups and arranging the dipoles of the groups in different polarization planes. Delay elements which vary from group to group may also be used and the dipoles may be provided with reflectors of pasteboard or paper covered with metal foil or sprayed with metal. The transmitter may be provided with an automatic switch cutting off transmission after each radiation.