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Two decoders; one loco (Was "12V LED and decoder output")

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Posted by tstage on Friday, April 19, 2019 9:24 PM

Mark R.
There is no such thing as a 12 volt LED - it either has an internal or external resistor to allow that 2.2 volt LED operate on 12 volts.

Thanks, Mark.  I seem to recollect reading that here on the forum at some point.

Do different color LEDs operate at slightly different voltages?  I'll find out on Monday whether the LEDs come with internal or external resistors.  I'm guessing internal.

Tom

https://tstage9.wixsite.com/nyc-modeling

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Posted by wvg_ca on Friday, April 19, 2019 9:14 PM

most LEDs range from 2.2 volt [red] to 3.2 volt [white], and already include resistors to operate at twelve volts ... they also -usually- are operated at maximum brigtness as well [-usually- 20 milliamp]  .. i would recommend adding extra resistors to reduce brightness, but that's just what i prefer ...

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Posted by Mark R. on Friday, April 19, 2019 7:44 PM

There is no such thing as a 12 volt LED - it either has an internal or external resistor to allow that 2.2 volt LED operate on 12 volts. That being the case, the resistance chosen will no doubt be calculated to operate that LED at its full potential on 12 volts. 

You don't need to add any more resistance, unless .... it is too bright for your liking, or you plan on living longer than the LED itself ! Smile, Wink & Grin

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

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Two decoders; one loco (Was "12V LED and decoder output")
Posted by tstage on Friday, April 19, 2019 7:40 PM

I will be using a 12V red LED with a TCS FL4 "light-only" decoder.  The FL4s have 12V output, if I understand the description correctly from the TCS website.  Like operating a 12V incandescent at a lower voltage to make it look more realistic and last longer, would it still wise to add a small value resistor to lower the intensity of the beam?

Thanks,

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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