| 摘要 |
PURPOSE:To keep the reception mode desired by a user in the state of dual audio reception by monitoring a voltage fed to an output mode setting terminal and keeping a voltage at a reception mode detection terminal forcibly to a 1st value when the monitored voltage is a 2nd voltage. CONSTITUTION:Suppose that the user desires a sub audio reception and selects a switch 23 to the position of a 2nd voltage, then even when a received electric field is weaker and a voltage at a terminal 14 is going to reach a 3rd value, since a holding circuit 30 keeps closing a switch 21, the terminal 14 keeps the 1st value. Since the circuit 30 has a hysteresis characteristic, even when the value of the terminal 14 may change, the output of the circuit 30 is not immediately changed. when the user selects only the output of a sub audio signal from output terminals 12, 13, the selection information is fed also to the reception mode detection terminal 14. Even when the voltage at the terminal 14 changes at a weak electric field or the like and the automatic changeover function is going to select a monaural output, the level of the terminal 14 is forcibly kept to the voltage (1st value) in the dual audio reception mode and not simply selected to the monaural output state caused in a conventional receiver. |
