Model Railroading > Tortoise Panel LED Indications

Hi All,

I've got a few Tortoise switch machines for my layout and I'm planning to operate them from a control panel. I want to have indicator lights on my control panel to display switch position. From what I've seen, the best way to do this is to have a bi-color LED to show red when diverging and green when lined straight.

Looking at bi-color LEDs, it looks like some of them have 3 leads while others only have 2. Which do I want to use for this application? I'm assuming I want the 2-lead ones to place in-line between my DPDT and the Tortoise itself (I don't know where that third lead would be wired to if I used those....)

Thanks in advance!
-Caleb

Assuming that you want to place the red/green in series with one wire to the Tortoise (the easiest way), then you must use a two wire, bi-polar red/green LED. If you decide to follow the advice to use two LEDs then you can wire the two LEDs in reverse parallel (that is, wired opposite polarity) and put that combination in series with the Tortoise.
In either case the polarity of the LED will determine which lights, simplest to try it and reverse the wiring to the LEDs if the wrong one lights.

Barry Draper

Thanks for your responses! I think I will go with the suggested 2 led approach. Thanks for the help!

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