| 摘要 |
An explosive device comprises a charge of explosive material which can be fired by feeding power from a firing circuit to an igniter circuit which includes an electrically-energizable fuse. In order to check the integrity of the igniter circuit, a monitoring circuit feeds a continuous stream of electrical pulses to the fuse circuit at such a low energy level that the pulses cannot cause ignition of the explosive charge, but they are sufficient to cause a light-emitting diode to emit short bursts of light. The production of these bursts is monitored by a receiver circuit via an optical fibre, and provided that corresponding signals are received continuously by a timer, a lamp indicates that the igniter circuit is ready for operation. If there is a break in the received signals, for example due to open-circuiting of the fuse, an alarm is operated. The connections between the igniter circuit and the monitoring circuit may be made via a demountable transformer.
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