| 摘要 |
PURPOSE:To permit automatic detection of a power source frequency so that said frequency can be set to a control device by subjecting the voltage waveform of an AC power source to half-wave current rectification and counting the comparison output of said waveform and specified voltage. CONSTITUTION:A transformer 1 is connected to the AC power source and the voltage dropped by the transformer is inputted through a current rectifier circuit 2 and a power source circuit 3 to a microcomputer 4. A photoelectric sensor 5 which detects articles to be transferred on a conveyor and a belt driving part 8 are connected to the microcomputer 8. On the other hand, the voltage is supplied from a winding which generates the low voltage of the transformer 1. The output of a half-wave current rectifier circuit 6 is supplied to a comparator 7 from which the digital signal for frequency counting is outputted. The microcomputer 4 discriminates whether the power source frequency is 50Hz or 60Hz by monitoring the signal for counting for 1sec. The microcomputer automatically sets the result thereof as a preset value.
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