| 摘要 |
PURPOSE:To obtain a miniature and lightweight unit and also to reduce its cost by reducing the number of components by oscillating a calling signal and howler signal by the same oscillation circuit. CONSTITUTION:Since a calling signal is an intermittent signal which is ON for one second and OFF for two seconds, a howler signal is oscillated in this OFF period of two seconds. Oscillation circuit 10 for generating the calling signal (16Hz) and oscillation circuit 20 for the howler signal (400Hz) are composed of a common circuit and under the control of oscillation control circuit 40, only either one is oscillated. Then, signals from oscillation circuits 10 and 20 are sent out via output transformer 60 after being amplified 50. Further, oscillation control circuit 40 controls circuits 10 and 20 on the basis of a signal of three seconds generated by oscillation circuit 30. |
