| 摘要 |
Circuitry for an LED indicator which can enable and disable the LED indicator at appropriate times. An LED indicator, for example an array of LEDs, is driven by a driving circuit including a control circuit. An input is configured to sense an input line voltage in the LED driving circuit. A further circuit is connected to the input and outputs a first signal or a second signal based on whether the sensed input line voltage is above or below a threshold value. Further, a signal line connects an output of the further circuit to the control circuit of the driving circuit. The control circuit disables driving of the LED indicator based on the further circuit providing an indication whether the sensed input line voltage is above or below the threshold value. The LED indicator may find particular application in an LED traffic signal. With such circuitry in the present invention, a signal which is not intended to illuminate will not in fact illuminate.
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