How do I determine resistor type for LEDs?

Model Railroader Electronics and DCC
1

I have a soundtraxx Tsunami2, TSU-2200 decoder for my LIRR Alco FA1 soldered in with a speaker. Runs great. Now I just need to install a headlight and red classification lights when it runs in reverse.

I have the LED’s i want to install. The light functions for the decoder puts out 100mA of current but I don’t see the voltage output. How do I determine what resistor to use? thanks

2

I have never gone wrong with a 1,000 ohm 1/4 watt resistor.

https://tonystrains.com/installing-leds-with-dcc-decoders/

3

Thanks! I was just reading that page too.

And I only need 1 resistor if doing 2 LED’s in series correct?

(Nevermind. That article just answered it.)

4

And the answer is, yes, two LEDs wired in series for the same function can share a single resistor.

Rich