| 摘要 |
PURPOSE:To control an output DC level to a prescribed value by controlling a voltage-controlled amplifier in the sound recording circuit of a tape recorder by comparing a DC component led out of the amplifier with a reference voltage. CONSTITUTION:A recording signal of a tape recorder, etc., is supplied to a signal input terminal IN1; and then supplied from an output terminal OUT2 to a recording amplifier RA and a meter amplifier MA by controlling a voltage-controlled amplifier 21 by adjusting a recording volume control VR at a DC control voltage input terminal IN3. The output of the amplifier 21 is applied to an error amplifier 22 through a DC component extracting circuit 26 consisting of a resistance R and a capacitor C and then compared with a refernce voltage at a terminal IN5. An obtained error component is supplied to the base of a transistor (TR) 2 forming a differential couple with a TR1 applied with the input signal. Thus, an output DC level at the terminal OUT2 is controlled to a prescribed value. |
