FUNCTION VANISHMENT CHECKING CIRCUIT FOR FUNCTION CIRCUIT

摘要

PURPOSE:To enable a safe dismantling of an explosive matter incorporating a function circuit by arranging a timer circuit adapted to disable the function circuit upon the reaching of the set time in a specified time after the start of operation and a display for indicating the vanishment of function. CONSTITUTION:In response to the passage of a metal body near a magnetic detector 2, a signal of a large amplitude is outputted from the circuit 2 and applied to a level selection circuit 6 via a rectifier circuit 3, a differentiation circuit 4 and an amplification circuit 5. The level selection circuit 6 applies a voltage Vi to a magnetic checking circuit 7 when the voltage level of the signal applied exceeds the specified value. The magnetic checking circuit 7 is so arranged as to be enabled upon the reaching of the set time for a timer circuit [ I ] 8 while to be disabled upon the reaching of the set time for a timer circuit [II] 9. Therefore, the magnetic checking circuit 7 starts to function when the voltage Vi is applied from the level selection circuit 6 before the reaching of the set time for the timer [II] 9 after the reaching of the set time for the timer circuit [ I ] 8. On the other hand, as the voltage of a battery 10 falls below a fixed level, the light emitted from a liquid crystal display 18 goes out thereby enabling the confirmation of vanished function in the function circuit.