| 摘要 |
PURPOSE:To adjust the sound volume of a car audio equipment automatically according to whether an automobile is running at an ordinary speed or low speed, or it is stopped. CONSTITUTION:The equipment is provided with a noise sensor 5 sensing a noise in the cabin of an automobile and with a filter 6 extracting a low frequency component of an electric signal outputted from the noise sensor 5, a decision device 7 deciding whether or not the low frequency component outputted from the filter 6 is larger than the preset level, a sound volume changeover device 8 increasing the sound volume of the car audio equipment when the decision device 7 decides the low frequency component is larger than the preset level and restoring the sound volume to the original sound volume when the decision device 7 decides the low frequency component is smaller than the preset level. The sound volume changeover device 8 is made up of a resistor 8a connecting in series with a manual variable resistor 4 adjusting manually the sound volume of the car audio equipment and a relay circuit 8b having a relay contact 8c connected in parallel with the resistor 8a. |
