| 摘要 |
PURPOSE:To individually adjust sound volume in response to the content of broadcast, by providing a plurality of sound volume adjusting circuits for a device broadcasting with voice for the content in response to a command signal, and selecting them according to the command signal. CONSTITUTION:When a command signal 1 or 2 is H, a sound of the content corresponding is synthesized at a sound generating circuit 7 as a digital quantity. Since an output of an OR gate 9 goes to H, a transistor switch 12 is conductive. A voltage divided at a variable resistor 15 and a resistor 18 is inputted to a D/A conversion circuit 8 as a reference voltage. The circuit 8 converts the digital input of sound into an audio signal 8a of an analog output in the rate in response to the reference voltage. This is the same for the case with command signals 3, 4, 5 and 6. Thus, the content of broadcast corresponding to the signals 1-6 is broadcast with a sound volume adjusted with corresponding variable resistors 15-17, allowing to individually adjust the content of broadcast at normal state and on emergency in a suitable sound volume. |
