| 摘要 |
PURPOSE:To detect and suppress a noise generated during the operation of a nonshorting switch with extremely simple constitution by operating a muting circuit by the outut of an active element which turns on through the operation of the nonshorting switch. CONSTITUTION:When a voltage +B is applied to an AM circuit via a terminal 2, a contact 4 and a terminal 1, the movement of the contact 4 intercepts the voltage supply to the AM circuit and also intercepts the supply of the voltage +B to the base of a transistor (TR) Q, which turns on; and a voltage developed at its collector is applied to a muting circuit M to intercept a sound, and at the same time, a capacitor C is charged. The further movement of the contact 4 supplies the voltage to an FM circuit and applies the voltage to the base of the TRQ again, which turns off, but the muting circuit M is applied with the discharging voltage of the capacitor C to continue its operation. When its voltage drops, the muting mode is reset. |
