| 摘要 |
PURPOSE:To give the control to the volume of the melody tone or the alarm tone by varying the capacity of the capacitor connected in parallel to the sound generator containing the piezoelectric element stuck to the diaphragm. CONSTITUTION:When the timing information of counter circuit 4 becomes agreement with set time 6, the coincidence detection signal is sent to AND circuit 8 from coincidence circuit 7. And signal f of 32Hz is applied to address counter 11 from circuit 8. Address counter 11 counts the signals sent from circuit 8 and then gives the count value information to code generation circuit 12. Thus the code information to the rhythm and musical scale is applied to frequency control circuit 13, and the clock pulse signal of the frequency corresponding to the musical scale is delivered from circuit 13. At the same time, pulse signals A-D are delivered from envelope control circuit 14 based on the code information to the sound volume sent from circuit 12, and thus MOS transistors 15a-15d which are connected in parallel to sound generator 18 are turned on. Thus the sound volume of gnerator 18 can be controlled in accordance with the capacity of capacitors 20a-20d each. |
