| 摘要 |
PURPOSE:To enable switching in the generation of bell sounds and electronic tones without separate circuits by arranging at least two or more attenuated modulation circuits for cyclically attenuated modulation of different audible frequency signals to be switched so that output signals of both the circuits will overlap to generate a false bell sound while only a specified transistor in one attenuated modulation circuit will be turned on to generate a normal electronic tone. CONSTITUTION:Output signals R and S of two attenuated modulation circuits 30 and 40 which provide a characteristic of attenuating in steps sequentially at a cycle T=0.0625sec. are fed to a sound emission circuit 80 overlapping, which enables the generation of a false bell sound extremely similar to the bell sound by the conventional bell striking mechanism. When a selector switch is opened, the output signal F moves to H, an AND gate 68 is opened to turn the output signal of an inverter 72 to L. The output signal G of the AND gate 68 move to H only when intermittent sound control signals D and E are at H thereby producing an intermittent sound signal. The output signal I of an OR gate 66 is the same in the phase. As the output signal of the inverter H is at L, an AND gate 64 is caused to close. |
