| 摘要 |
<p>PURPOSE:To avoid the burning of a solenoid, by delivering the electric signals to eject a cassette as well as to cut off a power supply in case the solenoid conduction time exceeds the set value. CONSTITUTION:A transistor TR1 is turned on and off by the input signals of an input terminal 6 of the input side and controls the conduction from a power supply terminal 7 to a solenoid 2. An arithmetic circuit 3 monitors the collector voltage of the TR1 and detects the state of conduction of the TR1. When the collector voltage of the TR1 is set at 0, that is, the solenoid 2 conducts, a prescribed positive integer K is stored in the address of a memory 4. Then 1 is subtracted every time the solenoid 2 conducts continuously for the prescribed T seconds. When the integer K is set at 0 (KT seconds later), the signals are applied to an ejection mechanism driving circuit 5 to eject a cassette as well as to cut off the power supply. Thus the burning of the solenoid 2 can be eliminated.</p> |
