GB1186758A - Improvements in or relating to Detonating Apparatus - Google Patents

Abstract

1,186,758. Control circuits for capacitor-type detonating apparatus. BLANICKE STROJIRNY, NARODNI PODNIK. 20 Nov., 1967 [19 Dec., 1966], No. 52581/67. Heading H2H. Capacitor-type detonating apparatus comprises the circuit arrangement shown, wherein the capacitor 4 is charged by a crank-actuated generator 1a, 1 and the components 10, 11, 13 ... 16 are provided to ensure that the length of the firing pulse is practically independent of the resistance of the firing circuit and that the voltage at the firing circuit varies according to the resistance to prevent electric stressing thereof. The values of inductances 13, 15 are chosen so that: (1) with the resistance at terminals 17, 18 equal to the maximum permissible resistance of the firing circuit, the members 4, 13 form a damped oscillating circuit whose period is twice the desired firing pulse length; and (2) with the terminals 17, 18 short-circuited, the members 4, 15 form a damped oscillating circuit whose period is also twice the desired pulse length. When the firing switch 12 is closed these two oscillating circuits interact to produce a pulse of the desired time duration at the terminals 17, 18. The impedance of the inductance 15 and the resistance of the firing circuit form a voltage divider and, by making the impedance equal to the maximum resistance of the firing circuit, the voltage at the terminals 17, 18 falls with decrease of resistance and vice versa. The connections 19, 20, 21 are associated with an ohmmeter incorporated in the apparatus.