Arming of the AE 1. When the mine is first laid, a hydrostatic switch starts an arming clock with an adjustable delay time of 1/2 to six hours. After this delay period, the first set of contacts (1), figure 231, on the arming clock are operated. If the relay (2) or ??? safety switch (3) should be closed as a result of failure or a mistake, then these arming clock contacts switch a scuttling charge (4) into circuit, which destroys the mine.

Ten second later, the second pair of contacts (5) of the arming clock are closed, and connect the main battery (6) to the coil and contact of relay (7), also to the heater coil of heater-coil relay (8). The battery has a nominal rating of 31 ampere hours, 12 volt. Nearly all the batteries in the circuit utilize nickel cadmium cells.

Two minutes later the heater coil relay (8) switches on the microphone current from battery (9). It also switches on a small sterilizing motor (10), which operates four swit-ches as described below.

Ten seconds later three contacts are operated by motor (10). One disconnects the scuttling charge, and the other two connect the main detonator (11) into circuit. The mine is now armed.

If the mine comes to the surface, it is scuttled by a hydrostatic switch (12), which connects the scuttling charge into circuit.

Six month after laying, the mine is scuttled by the fourth contact operated by motor (10).

Figure 231 - AE 1 Unit Circuit