ELECTRONIC SAFE/ARM DEVICE

An electronic safe/arm device is powered internally by a low-voltage, periodic power source (12) that has insufficient voltage by itself to fire the detonator (18). The circuit therefore includes a step-up transformer (14) from which sufficient voltage to fire the detonator (18) is obtained. The step-up transformer (14) charges an arming circuit (16) which stores high-voltage power to fire the detonator (18) and also powers the firing circuit (20) which discharges the stored high-voltage energy through the detonator (18) at the appropriate time, to fire the device. The low-voltage, periodic power source (12) may include a low-voltage battery (120) and a dynamic switch (126) for providing periodic pulses of low-voltage energy to the primary winding (140) of the transformer (14), and the dynamic switch (126) may be powered from the output of the transformer (14), so that the low-voltage battery (120) has insufficient voltage to power the dynamic switch (126). Accordingly, highvoltage energy derived from the output of the transformer (14) is required to operate the circuit, providing assurance that the device will not fire if the circuit is damaged.