| 摘要 |
An accessory maximum speed signalling device which is used with a motor vehicle having a first housing and a speedometer including a rotatable magnet in the first housing, the magnet producing a rotating magnetic field having field lines which extend outside the first housing. The accessory device includes a sensor adapted to be located within the field lines which extend outside the first housing but without the first housing, the sensor being sensitive to variations in the magnetic field lines which extend outside the first housing and emitting an electric signal representative of the variations. A second housing, connected to the sensor, includes a speed alarm, a control circuit for receiving the signal emitted by the sensor and actuating the alarm when the signal reaches a predetermined threshold, and a setting device for adjusting the threshold. |
