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DC Locomotives - Installing Directional LEDs

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DC Locomotives - Installing Directional LEDs
Posted by A214943 on Tuesday, January 29, 2013 5:33 PM

Where can I purchase boards containing the circuit to connect front and back locomotive LEDs? 

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Posted by Doughless on Tuesday, January 29, 2013 6:36 PM

The manufacturers use printed circuit boards for directional lighting in their DC/DCC ready locomotives.  Try searching for replacement boards from their parts department.

LED's will require the use of resistors between the board and the LED, ie. in the circuit..  1000 Ohm resistors are common for this.

- Douglas

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Posted by Texas Zepher on Tuesday, January 29, 2013 8:08 PM

I don't know, but I do know you can build your own for only the cost of the LEDs and 6 diodes.

This is a well known circuit and can be found all over the internet such as this:

http://www.mrollins.com/constant.html

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Posted by A214943 on Wednesday, January 30, 2013 6:27 AM

Thanks to all for your comments and help!

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Posted by richg1998 on Wednesday, January 30, 2013 6:20 PM

Texas Zepher

I don't know, but I do know you can build your own for only the cost of the LEDs and 6 diodes.

This is a well known circuit and can be found all over the internet such as this:

http://www.mrollins.com/constant.html

Notice, he uses 1.5 volt light bulbs. That circuit will not work with LED's.

LED's usually require two to three volts.

Rich

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.

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Posted by bobwrght on Wednesday, January 30, 2013 6:52 PM

You can just use Led's and resistors. Led's only light in one direction. Use the 1000ohm resistor on one wire to each led. 1000ohm is good up to 12v. Take the led with the resistor attached and touch each rail with power on with each wire and you will see it will only light one way. Flip it over and reverse your power pack and it will light in the other direction.

Bob

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Posted by richg1998 on Wednesday, January 30, 2013 7:33 PM

It appears the OP is asking about DC locos running on a DC layout.

The LED will not light until the voltage gets high enough.

At 12 VDC with a 1k resistor, the LED draws about 9 MA. 

Lower voltages, a lot dimmer.

DC layouts rarely ever get to 12 VDC.

If he is using DCC, he did not say.

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.

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Posted by A214943 on Thursday, January 31, 2013 4:13 PM

Thanks again for all of the comments.  Yes, it is a DC layout.  Sounds like LEDs are not the best application.  I will try a circuit as noted in the material referenced using 1.5 volt bulbs. 

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Posted by Texas Zepher on Thursday, January 31, 2013 8:04 PM

richg1998
Texas Zepher
I don't know, but I do know you can build your own for only the cost of the LEDs and 6 diodes.
Notice, he uses 1.5 volt light bulbs. That circuit will not work with LED's.

Ah, good point.  It requires a modification so it will work with LEDs.  I should have been  more careful and hunted up a proper circuit.

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Posted by bobwrght on Saturday, February 2, 2013 5:08 AM

Try the 1000ohm resistor and leds. No diode needed. I have installed bunches in Athearn and Bachmann engines and they all work. At low voltage the lights will come on. The 1000ohm resistor is to limit the top end of the voltage so you don't burn out the led at top speed.

Bob

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Posted by BigDaddy on Sunday, January 17, 2021 2:05 PM

Sorry this was supposed to go in the Bachmann Mikado thread.

There are constant voltage circuits,  how directionality works, unless you use 2 cirucuits is over my paygrade.

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by rrinker on Sunday, January 17, 2021 2:09 PM

 That simple circuit with the LED and the CL25N3 driver is directional as is. The LED will only light when the polarity is correct, so on one ond of the loco, the LED conencts to the right rail and the driver connects to the left rail, for the other end of the loco, flip those connections. If they are backwards (rear light goes on when loco moves forward), just reverse both circuits.

                               --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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