| 摘要 |
PURPOSE:To reduce the dispersion in level setting by providing an amplifier, a comparator, a clamp circuit, a buffer circuit and an attenuation circuit so as to set easily a maximum value of a control current to the attenuation circuit thereby preventing the fluctuation of a recovery time of a time constant circuit. CONSTITUTION:An input signal given to an input terminal 2 is given to the amplifier 46 via the attenuation circuit 24, its amplified output is extracted from an output terminal 12 and also compared with a reference level by the comparator 28. A potential output level of the comparator 28 is set by the clamp circuit 70 to a prescribed voltage or below and its output becomes a base input of a transistor (TR)74 as the buffer circuit. The operating current in response to the input flows to the TR74 and a capacitor 84 of the time constant circuit 82 is charged by a prescribed time constant. That is, an attack time and the recovery time to drive a TR42 are set by the circuit 82. The operating current flowing to the TR74 becomes a base input of the TR42 via the circuit 82 and a control current is given to the attenuation circuit 24 by the TR42. |
