If you use 1 resistor on the common lead for 2 LEDs attached to different functions, just be sure to not EVER turn them both on at the same time. This is somewhat acceptable for directional headlights so long as you never change the programming from directional, thus only one or the other can be lit, but in general you should use 1 resistor per LED. If space is tight, a small surface mount resistor will work, a pair of 805 size resistors will fit in the same or less space than a single axial lead 1/8 watt resistor. Or you cna take a small scrap of PC board and cut a groove down the middle and straddle the gap with the resistor and use it as a terminal strip of sorts. Ulrich even has such a board already made up with the resistors attached.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Below is a useful link with a link to a resistor color code chart which I see you need. This fellow is in some Yahoo DCC Groups.
http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Thank You, I appreciate your gentle guidance and advice. Algebra--Ohm's Law was never a long-suite so I am very appreciative of the help.
Russ
Much appreciated advice, thanks for taking time to guide a fellow model rail.
Spike,
A 1K (1000) ohm resistor would be a good starting point. If it's too dark then go with an 830 ohm or smaller. Generally speaking, 1K resistors are just about right.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
A 33K resistor is a little large. Orange-orange-brown is a 330 resistor. If it were 33K the colors would be orange-orange-orange.
If the resistor supplied was 330, then you could get away with a single 1K resistor for both. Brown-black-red.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
I,m upgrading some of my diesels ultimately to DCC, but for the moment my question relates to wiring the resistors to the forward and rear main lights. I'm using two of the 1.8 mm LED at each end, due to space limitations one resistor to one side of the led set (wired parallel)would be convenient. For individual use a [thirty three k ohm (orange orange brown) ?] resistor is supplied. What value or what would be a good starting point to use a single resistor. I am working in HO, and power will be supplied from the pc board out of an Athern AC 4400 engine.