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Hi i would like to install a by color led red and green to my layout, the led would be for my turnouts [switches]so that when the points are throwen in one direction it would light red and throwen the other it would light green. if anyone outthere help me it would be appriciated thanks robert



Robert, you have 2 choices.

Bi-color LEDs come in two types, either 2 leads or 3 leads. The 2 lead style show RED when the DC voltage is connected with the positive side to one of the leads and shows GREEN when you reverse the connections.

The 3 lead type has one color connected to one lead and the other color connected to one lead and one lead common. Typically you would connect the common lead (the center lead of the three) to the DC negative and connect the DC positive to one of the other two with a switch which is operated by your turnout. Arrange the switch connections so tha you get the color you want. This is probably the easiest way to do it.

If you want to use the 2 lead style then one way to make this work would be to use and AC current supply. Connect one lead to one side fo the AC supply. Connect the opposite ends of two diodes together and connect the other end of each diode to one of the poles of the switch that is opperated by you turnout. Connect the other side of the AC supply to the common diode connection and the operating contact of the switch to the other LED lead. Again, aarange the switch connections to get the color you want.

I hope you understand this - I don't know how to draw a picture in this note.

Dale Gloer

-- Dale Gloer (dgloer@ca.ibm.com), February 20, 2001.

Hi dale i thank you fore the info,i will the three lead led. but on the two lead i am a little confused as to which diodes to use if you could hand draw a rough diagram i would be gratefull thanks again robert


Hi dale i just received a message that i do not understand the meaning,please explaine i am new at this computor stuff. I responded to the answer that i received from you regarding turnout indication,i will try the three pole led.the problem is that i use atlas switch machines and when i press the button for either side, the points move,but as soon as the button is released the power is no longer there,and therefore the led. does not light up. if you can scetch out a rough diagram for the two pole led with the diodes i think that may work. thanks for your time



the solutions that I suggested require separate switch contacts that are operated by the turnout mechanism. The switch contacts are used to control the LEDs. There is no easy (my opinion anyway) way to indicate the position of an Atlas (or other twin coil switch mechanism) without using contacts to sense the position.

Here is a rough diagram of how to connect a 2 lead LED

AC -------->|---------------- \ 2 lead LED in | -------------->|--------- ------|<---------------- -|<- SPDT switch operated by turnout mechanism

For 3 lead LED

------------>|------ / | DC +ve ----------------------------- 3 lead LED --- DC -ve | ------------|<------ SPDT switch as above

Hope this helps

Dale Gleor

-- Dale Gloer (dgloer@ca.ibm.com), February 21, 2001.

Robert, I found your question in the Wiring for DCC page, so, assuming that you are using a DCC system you can do the following with a three-lead bi-color LED. Wire the common lead to the turnout frog, then wire one other lead to one of the stock (outer) rails(or its feeder), and the third lead to the other stock rail. The constant DCC voltage will keep one or the other color of the LED lit, depending on which way the turnout is thrown. Piece of cake! Doesn't need switch machine contacts, and there's negligable drain on the DCC power supply, even with a whole mess of indicators. Doesn't work with regular DC block control. I use this method, using individual LED's on the differing route lines on my control panels. Good luck--Brad

-- Brad Taylor (joinhands@aol.com), February 21, 2001.

Robert, If you are using Atlas switches and Atlas twin coil switch machines there is no place to directly connect up turn-out indicator LEDs. I suggest....

1. Use an Atlas brand accessory known as a snap-switch to provide the switch contacts to operate indicator LEDs. Wire the control coil wires in parallel with those of the switch machine so that they work together. There should be an indicator light connection diagram included with the snap-switch.


2. Use a Tortiose switch machine instead of the Atlas twin coil unit to control the turnout. The tortoise has auxilliary contacts that can be used to control indicator lamps. A wiring diagram is included with the Tortiose unit.

Either of the above schemes may require a power source other than simple track power. But rectified DCC from the track will provide ~14 Vdc. Be sure to include a resistor to limit current to the LEDs. The other replies failed to mention that.

[Actually the method of connecting a 3 wire bi-color LED to a polarity corrected powered frog & the stock rails is quite clever for a simple works-only-with-DCC indicator. But again be sure to include a resistor to limit LED current (from the LEDs mid connection to the frog), and 2 diodes, one connected in series with each LED, to protect them from reverse voltage breakdown.]


-- Don Vollrath (dvollrath@magnetek.com), February 28, 2001.

Just wire a two wire bicolor (red green) LED in series with one leg of the power to a tortoise. When the tortoise reverses the LED changes color. It's easy. I'm using 12 volt LED's from Mauser.

If your LED shows red when the switch is green, just reverse the leads on the LED.

-- Steven Barkley (BaylorMax@aol.com), June 24, 2001.

I use the Atlas Switches on my control panel. Each switch is wired and marked the same. So I know what the state of the switch is since the position of the button, which is where the button was last used, shows the position of the switch. If the button is to the right, I know that the switch is in the closed position. If to the left, the thrown position. All without any lights.

Bob Guercio

-- Robert Guercio (rguercio@monmouth.com), January 30, 2002.

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