| 摘要 |
PURPOSE:To properly cut off electric power for the saving of the electric power according which of an internal power source and an external power source supplies the electric power to the electronic equipment by prohibiting the electric power from being cut off when the electric power is supplied by the external power source. CONSTITUTION:In an electronic musical instrument main circuit 1, a microcomputer 2 controls the whole electronic musical instruments and a timer for various processes is incorporated. The computer 2 judges that AC electric power is supplied from a power supply circuit A based on the detection signal from a 2nd detection circuit 24 which has a logical level '1'. Consequently, when the main circuit 1 is energized by the battery power source 8, automatic power- OFF operation is performed, but when the electric power of the AC power source 9 is supplied, the automatic power-OFF operation is not performed. |
