With a 1K resistor you should be good around 12 volts. The extra 150 ohm resistor is to adjust the relative brightness of the red or green LED in the bicolor unit. You probably should have 2 of those if it's a two head signal. You'll notice when you apply power that either the red or the green aspect will appear brighter as you switch back and forth. Put the 150 ohm resistor int he lead for whichever one is brighter and it should be more balanced out. Normally it's the red that is brighter than the green.
--Randy
Modeling the Reading Railroad in the 1950's
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So do I need a seperate 150 ohm resistor for each green wire? Only one came in the package. Also what voltage would you recommend. I don't want to burn them out.
Thanks
I have a pair of HS-2 South Bend duel head target signals that I would like to wire thru my Tortoise switch contacts to show the way the turnout is aligned. The problem is that the signals come with 2 different resistors, a150 ohm the directions says go to the green wire and a 1K ohm to the yellow. There are 2 red wires, 2 green wires and a common yellow wire for the 2 bicolor tri-state LEDs.
It seems to me that I only need one resistor for the yellow common wire for both LEDs depending on the brightness and voltage. South bend's directions seem confusing to me. Any ideas out there on how to wire and voltage recomendations?