| 摘要 |
<p>A usage counter (10) has input terminals (11 and 12) connectable to the terminals of a jump-starting battery pack (15). The counter has an IC comparator (21) which generates an output signal when battery voltage drops below a predetermined reference level. If the output signal persists for a predetermined time period, indicating an attempt to jump-start an engine with the battery pack (15), an IC timer (31) is triggered to output a count pulse which is inverted by inverter (40) and then counted, as well as displayed by an IC counter/display circuit (45). The usage counter circuit (10) is powered by the battery pack (15) and has a Zener diode (17) which provides to the IC circuits a limited supply voltage which is unaffected by voltage spikes which might appear at the battery pack terminals. A capacitor (36) maintains the reference voltage level despite momentary drops in battery terminal voltage.</p> |
