| 摘要 |
A battery pack has a pair of input/output terminals adapted to be connected across a source of charging voltage, and a lead-acid battery connected across the input/output terminals. A Zener diode is connected in series with a resistance across the input/output terminals, the resistance forming part of a trigger circuit for triggering an alarm signal to actuate a visible and/or audible annunciator when the charging voltage exceeds a threshold level. In one embodiment the trigger circuit is an IC comparator having one input connected to a reference voltage drive from a voltage divider connected across the input/output terminals, and the other input connected to the trigger voltage across the resistance in series with the Zener. In another embodiment the trigger circuit includes a pair of transistors, one being turned ON by the trigger voltage and in turn ON the second transistor to produce the output signal and provide a feedback to latch on the first transistor.
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