| 摘要 |
First and second Zener diodes respectively connecting first and second output terminals of a differential amplifier to the base of a transistor, the collector of which is connected to an indicator lamp and the emitter of which is grounded. One input to the differential amplifier is connected to a point in the charging system for the vehicle battery such as the output winding of an alternator, and the other input is connected to a reference potential that varies with the rectified output voltage of the alternator. When the output of the charging system varies from predetermined levels, one or both of the Zener diodes break down to bias the transistor into conduction, thereby illuminating the lamp. Otherwise the Zeners effectively remove the bias voltage from the base of the transistor keeping it off.
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