| 摘要 |
PURPOSE:To secure the proper tone for alarm by securing the operation of the radio's low-frequency amplifier circuit as the oscillator circuit and then inserting the impedance between the amplifier circuit and the power source to secure the intermittent oscillation. CONSTITUTION:When switches S3 and S4 provided to low-frequency amplifier circuit 51 of the radio are switched toward fixed contact (a), circuit 51 functions as the radio amplifier. And with switching of S3 and S4 toward fixed contact (b), the positive feedback is applied to circuit 51 via impedance 9 to generate the buzzer tone. Circuit 51 is reduced then for the power voltage via impedance 11 along with reduction of the amplification factor, and thus the oscillation becomes unsteady with repetition of the oscillation and stop. Thus the intermittent buzzer tones can be obtained. |
