| 摘要 |
PURPOSE:To detect the variance of the frequency of an oscillator easily with a simple circuit constitution, by dividing frequencies of oscillators, where frequency precisions approximate each other, by a prescribed ratio to reduce the number of digits and detect precisions. CONSTITUTION:Quartz oscillators 1 and 2 oscillate, for example, 5MHz normally, and the fluctuating frequency of the oscillator 2 is denoted as 500Hz. Their frequency dividers 3 and 4 of frequency division ratio 1110<2> respectively, and outputs are mixed by a frequency difference detecting circuit 13, and a frequency of 5Hz is generated as the output. A pulse of a one-second width is taken out from the frequency divider 3 to open a gate circuit G3 for one second, and 5 pulses are counted by a counter 5. The count value is read into a latch circuit 6 and is displayed on 9. The output of the circuit 6 is compared with a set value of a preset counter 7 by a comparing circuit 8 and if this output exceeds the set value, the circuit 8 issues a signal to operate an alarm device 10. |
