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Can I put Color-changing multi-color RGB LEDs in series??

I need to run a bunch of slow-changing multicolor off of 12vdc.  The LEDs are each rated 2.5-3.4V 20ma.  I'd like to keep efficiency up by reducing the number of series current-limiting resistors and the voltage across them.  So... 

Can you put 3 multi-colored LEDs in series with a current limiting resistor (typ 150 ohms) to run off 12vdc... like you do with standard LEDs?  The datasheet specs a operating voltage range and 20ma current.

Or...  Does the current draw (effective resistance) of the LED change as the colors change??... Example: When displaying purple, red & blue are both lit. But for red, only the 1 internal LED is lit.

If the current changes and the different LEDs are out of time, it would change the voltage across the different LEDs and the series resistor.

(I know you can't run an on-off flashing LED off a higher-than-spec'ed voltage because the current goes between almost 0ma and 20ma, putting nearly the full supply voltage across the LED when it is OFF.)

So, can I put them in series successfully??


Also, how accurate is the color-changing timebase?   Will they quickly go out of sync.. assuming the same brand and lot.

steveastrouk3 months ago

Are they nominally sold as "12V" leds ? These often are, and contain their own current limiting.

They will probably lose sync very quickly./

You can and they WILL lose sync fairlly quickly however this can be an advantage as the colours then mix to give a wider range.