| 摘要 |
PURPOSE:To enable to eliminate transient noise at switching surely, by detecting the lowering in rapid electric field strength produced at switching of a switch for a wireless microphone and using this detected output. CONSTITUTION:When a switch is turned off for a wireless microphone and the voltage level of the point A rapidly decreases, the change is given to the base of a PNP transistor (TR)42 via the 3rd time constant circuit consisting of a capacitor 40 and a resistance 41 to turn on the TR42. Thus, the voltage of the collector C of the TR42 is increased. This voltage is applied to a TR32 via a protective resistance 44 and a reverse blocking biode 46 to compulsively turn on the TR32 and turn off a switch section 16 at the same time. The period when the TR32 is compulsively turned on with the output of a detection circuit 38, is decided with the 3rd time constant circit and the period lasts until normal squelch operation sufficiently starts. |
