| 摘要 |
PURPOSE:To realize the switching between AM and PM through a simple circuit, by carrying out the correction of the time differential with rotation of the rotor and at the same time detecting the change of the contents of the time counter. CONSTITUTION:It is supposed that the time band of PM is shifted to the time band of AM while lamp 68 glows. In such case, reversible counter 15 counts 1 at 11:00 PM, and the output reverses the output of NAND gate 45 to 0 at 12:00. This reverse output reverses the state of FF31 and then lights up lamp 67 to display AM. On the other hand, the time is set to 1:00 AM. And in case the disk is turned counterclockwise under these conditions, counter 15 is switched to the side of the subtraction counter circuit with the first pulse supplied from NAND gate 40. At the same time, the contents of counter 15 changes to 0 from 1. When the disk is turned more counterclockwise, the outputs of terminals A1 and D1 of counter 15 are reversed to 0 and 0 each with the second pulse sent from gate 40. And the output of NAND gate 43 is reversed to 0. As a result, the state of FF31 is reversed to light up lamp 68 of PM. |
