| 摘要 |
PURPOSE:To sound record the voices of many persons in good condition by using a switch for discharging resistance of capacitors for signal rectification of an AGC sound recording circuit and another switch which performs the switch between an active and inactive actions of a filter consisting of a capacitor and a resistance. CONSTITUTION:A transistor 14 is turned off and a discharging resistance 13 is not earthed at the time of normal sound recording where a switch 23 is connected to the left side as shown in the diagram. While the AGC resetting time is usually set at the values between several seconds and several ten seconds in terms of the parallel value of the input impedance of a load variable circuit 8 and the output impedance of a signal rectifier circuit 7 as well as the capacity of a smoothing capacitor 7a. An LPF containing a resistance 21 and a capacitor 22 is added together with an HPF containing a capacitor 18 and the input resistance of a pre-amplifier 2. Thus the comparatively wide range characteristics are obtained when the switch 23 is switched to the left side. In such a way, the AGC resetting time is reduced and the bands other than the human voice bands can be cut and therefore the voices of conferences, etc., can be sound recorded with extremely high articulation.
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