Abstract: A CPU deactivates an A/D converter section before it stops operating in an idle mode. When any one of the keys in key matrices is pushed, the key matrix including the key pushed generates a voltage. The voltage is applied to the A/D converter section and one of buffer circuits. If the voltage is lower than the threshold voltage of the buffer circuit, the output signal of an AND circuit changes, and an interrupt-signal generating circuit generates a signal for releasing the idle mode. In response to this signal, the CPU starts operating and activates the A/D converter section.

Abstract: A filter apparatus has a current-detecting coil. The coil detects a high-frequency leak current flowing from the phase-windings of a motor to the earth terminal through the closed case of a compressor. A current-canceling circuit generates a current similar in waveform to the high-frequency leak current detected by the coil. The current thus generated cancels out the high-frequency leak current.