| 摘要 |
PURPOSE:To reduce shock sound at application of power at sound recording state or reproducing state by providing a circuit bringing temporarily an amplifier to the interrupting state just after application of power. CONSTITUTION:The amplifier 6 is brought into the operating state only when an ON signal is outputted from a terminal S. In applying power to a sound recording and reproducing changeover switch S1, a transistor (TR) 163 is turned on while a capacitor 165 is charged only and a potential of a point M is nearly coincident with a voltage P by the TR164. When the sound recording and reproducing changeover switch S1 is thrown to the position (a), since a voltage Vcc is applied to a resistor 154, a capacitor 155 is charged, a voltage at the point M increases slowly by taking the voltage P as the start point and when the S1 is thrown to the position (b), since the capacitor 155 is dischrged via resistors 154, 156, the voltage at the point M is decreased slowly by taking the voltage P as a start point. Thus, the amplifier 6 is interrupted while the voltage M changes from the voltage P to the voltage O or from the voltage P to the voltage Q and no shock sound is outputted to a terminal B. |
