| 摘要 |
If a person treads on a cord or net connected to a magnet (7A) the magnet is displaced from the sensor (3A) and a resistor (8) is short-circuited. This produces a higher voltage to a light-emitting diode which shines more brightly and a buzzer (10) is activated This indicates to an operator that someone is in the vicinity of the sensor. Switches (as 17) are then actuated to supply direct voltage from a source (12) to an action device (5A) including a tape recorder and loudspeaker. Alternatively, a searchlight, or a smoke or toxic gas generator are provided. |
