| 摘要 |
<p>PURPOSE:To save power by disposing a switch between an output circuit and a power supply and switching the switch according to presence/absence of a load connected with the output terminal. CONSTITUTION:A magnetic recording/reproducing unit comprises a switch 8 disposed between a power supply 3 and an output circuit 2, two resistors 5, 6 connected in series between the power supply 3 and an output terminal 1 connected through a capacitor 9 with the output circuit 2, and a potential judging circuit 7 which reads out the potential between two resistors 5, 6 and opens the switch 8 when a high potential is read out whereas closes the switch 8 when a low potential is read out. In other words, when no load is connected to the output terminal the potential between the intermediate points of two resistors goes high whereas the potential goes low when a load is connected to the output terminal, and the switch is controlled based on the potential level. According to the constitution, power can be saved.</p> |
