| 摘要 |
PURPOSE:To smoothly replace a sound by setting plural time limits, outputting a control signal to input and increase and decrease a switching signal outputted from a timer circuit to an electronic volume circuit, inputting the result to a signal adjusting circuit and switching a signal for broadcasting. CONSTITUTION:A timer circuit 1 outputs 1 or plural switching signals to switch at a time interval set by a time limit setting circuit 3. In accordance with these switching signals, plural two electronic volume circuits 4 and 5 are successively selected and two outputs are increased and decreased. In accordance with the output of these two increasing and decreasing electronic volume circuits 4 and 5, a signal adjusting circuit 6 amplifies and outputs two corresponding input signals and the output signal is outputted through an amplifier to a speaker 8. Thus, while two signals are simultaneously increased and decreased, a smooth sound is replaced.
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