piclist 2002\09\06\104537a >
Thread: BI-COLOR LED
www.piclist.com/techref/displays.htm?key=led
picon face BY : Morgan Olsson email (remove spam text)



Hej Harold Hallikainen. Tack för ditt meddelande 15:09 2002-09-06 enligt nedan:
>Another trick on 2 pin bi-color LEDs is to put a couple resistors in series (I use about 240 ohms) between +5V and ground. Put the LED between the junction of the resistors and the PIC pin. Tristate the pin to turn the LED off (note that PIC power dissipation will go up a bit since the pin is held at half Vcc by LED leakage current).

The bigger power waste is that current also flows in the resistor that is parallel to th elit diode.  And when both are off, current flows in both resistors.

One method is to replace both resistors with zeners, and add one current limiting resistor in series with the led.  (if we don´t dare to rely on totla series resistnace of PIC+LED+zener, which i don´t).

/Morgan

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