| 摘要 |
An electrical meter has light-emissive display elements and a meter circuit featuring electrically floating input terminals relative to device ground, and offers a potentially significant cost advantage compared to available alternatives in low-accuracy measuring applications. A series string of the light-emissive display elements are physically arranged along a line in order of increasing turn-on current threshold of each element so that they are successively turned on along the line with increasing current to be measured. A control circuit included in the series string has first and second semiconductively-complementary active semiconductor devices, such as an NPN and PNP transistor, each with base, emitter, and collector. The input-sensing conductor, such as a base, of each active semiconductor is a respective floating input of the meter. The semiconductors have at least two output control conductors, such as collector and emitter, two corresponding control conductors being wired together (as emitter to emitter) and the other two being wired into the series string. The light-emitting elements are suitably semiconductor diodes (LEDs), incandescent bulbs, neon bulbs, or other devices, with resistive shunting where necessary. Two such meter circuits are wired back-to-back with their light-emissive elements arranged physically back-to-back to form an uncomplicated galvanometer device for measuring electrical currents of either positive or negative polarity.
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