| 摘要 |
PURPOSE:To minitor the output of an audible signal tone generator, by comparing the output of a testing audio signal tone generator with that of an audio signal tone oscillator, and using a coincident signal when both coincide with each other >=2 times. CONSTITUTION:The 2nd FF circuit 18 outputs a 1-level signal synchronously with a clock CLKB11 to drive an address counter 13 through the 1st OR gate 12 and next data is outputted from an RAM7 to make a comparison between the outputs of the 1st and the 2nd buffer memories 6 and 8 continuously. Thus, when >=2 coincidence signals are obtained successively in a comparison between the output of the audio signal tone oscillator 4 and the output of the testing RAM7, it is judged that the output of the oscillator is normal. The output of the 1st FF circuit 9, on the other hand, is inputted to the 2nd ANG gate 20 through an inverter 19 and at this time, the utput of the 2nd OR gate 21 is 1, so the output of the 2nd AND gate 20 goes down to 0, showing that the audio signal tone oscillator 4 is normal on a display pilot 22. |
