| 摘要 |
PURPOSE:To make it unnecessary to operate a switch in accordance with a power supply-frequency, by discriminating the power supply frequency on a basis of clocks, which drive a microcomputer, to count the time. CONSTITUTION:The sine wave of a power supply 1 is shaped to a square by a circuit 2 and is inputted to an input device 301 of a microcomputer 300. A control device 304 transfers the count number of square waves which are inputted to the input device 301 within a constant count of the signal of clocks 8. An operating device 303 compares preliminarily stored frequency data with this count number of square waves to discriminate and store the inputted frequency of the power supply 1. In accordance with this stored data, pulses of square waves are counted to calculate the time, and this time is stored in a storage device 302. This stored calculated value is sent to a time device 4 through an output device 305 and is displayed. |
