| 摘要 |
<p>The battery supply (11) to the measuring instrument (10) is stabilised by a series transistor (12) whose base is controlled by a zener diode (14) and transistor switch (17). The base of the switching transistor is connected via a diode (18) to one of the input terminals (15) of the measuring circuit. A capacitor is connected between the transistor base and supply negative rail (20). If no input signal is present at the measuring circuit terminals (15, 16), the switching transistor is turned off and the power supply is disconnected from the instrument. The supply is only connected when a signal appears at the input.</p> |
