| 摘要 |
PURPOSE:To operate a timer accurately with the similar operation according to the power source frequency used by controlling the electric energization of a synchronous motor adapted to form timer discriminating the frequency of the power source supplied. CONSTITUTION:The commercial power source frequency and the 55Hz frequency are processed with frequency-voltage conversion circuits 11 and 12 of a frequency discriminator circuit 5. When the commercial voltage is 50Hz, the output of a comparator 13 moves to a high level and with a switch 7a of a control circuit 6 kept ON, a synchronous motor forming a timer is driven continuously with a 50Hz power source. On the other hand, when the commercial power source is 60Hz, the output of the comparator 13 goes down to a low level and the switch 7a is turned ON intermittently by a pulse with the duty ratio of 5/6 via an OR circuit 14 to feed the synchronous motor with a 60Hz power source intermittently, which is the same in the revolutions as when it is 50Hz. Therefore, the timer is operated accurately with the similar operation according to the power source frequency being used. |
