| 摘要 |
<p>The lock has give spring-biassed pushbuttons, operating in a low voltage circuit, which must be pressed in a specified sequence to permit a device to operate. The pushbuttons operate contacts which energise the coils of solenoids which in turn close contacts when energised. The various contacts are interconnected so that only the correct sequence of pushbutton operation permits the solenoids to remain engaged. If an incorrect sequence is entered the solenoids all reset and an audible or visual alarm is initiated. The installation may be battery powered for extra security and may include a facility for releasing gas or a coloured liquid if the alarm is activated.</p> |
