2671 tender lights

[Michael6268]

Recently acquired really nice Lionel 2671 tender. I want to install the lights/ 3 light bar in the back. I know it's been discussed before, but what do most people do for colors? I'm thinking the outsides red and the center clear.

[rtraincollector]

Jeff at train tender sells the kits with the set up all there. [e-mail]

[ADCX Rob]

rtraincollector

Jeff at train tender sells the kits with the set up all there...

The Train Tender

[rtraincollector]

But to answer your actual question most are red out side with white inside, that I have seen

[Michael6268]

I'll be odering one from Jeff in the morning!   And the outside red lights wins!   Thanks guys! Anyone know of a good red dye for plastic? 

[teledoc]

Have you considered using Nail Polish??

[lionelsoni]

I used 3-millimeter LEDs.  The white middle lamp lights when backing up.  The other two are red and are lit in both directions.

[Michael6268]

Sounds complicated. I would prefer leds.      Easy enough to have all 3 constantly lit with a resistor and leds at a constant voltage.  But how bout variable voltage?  And making the center directional?  Any tips? 

[lionelsoni]

My opinion is that regulating LED current for constant brightness is not worth the trouble.

An incandescent lamp's light output varies approximately as the 3.5 power of voltage and its color also varies substantially, making track-voltage fluctuations very obvious.  LEDs on the other hand put out light directly proportional to current and absolutely steady in color.  An LED's low forward voltage makes it easy to supply that current through a simple ballast resistor nearly in proportion to the track voltage.  The bottom line is that one is likely not even to notice an LEDs' brightness variation.  At least I don't.

To get directional lighting in the tender, I have added a tether from the locomotive.  This also carries a wire for the coupler, which I control from the locomotive.

[Michael6268]

Sounds like the way to go. I like leds too because i don't want to risk melting the shell due to the heat of the 14v bulb.

[Michael6268]

What did you use for rectification? Did you use a FWB and a capacitor?

[lionelsoni]

I have a rectifier for the entire motor, associated with other stuff that I'm doing in the locomotive.  But if I were modifying a conventially-wired locomotive for this, I would use a half-wave rectifier, that is, just a series diode, no capacitor, and a ballast resistor for each LED, connected to track voltage supplied by the tender's wheels and pickup.  Full wave rectification and filtering are harmless, but the LEDs will look the same without them.  It wouldn't be a bad idea to put a reverse-biased shunt diode downstream of the rectifier diode, to catch any high-voltage spikes that might exceed the rectifier's peak reverse voltage.

----->|---------------...
         |    |    |
         |    |    |
         |    /    /
         |    \    \
         |    /    /
        ---   |    |
         ^    |LEDs|
         |    v    v
         |   ---  ---
         |    |    |
         |    |    |
----------------------...

For a directional light, I would use the same circuit, but connected between the track voltage and one of the locomotive's motor brushes, through a tether.

Although not needed for the lights, as long as I were implementing a tether, I would add a wire between the locomotive and tender pickups.

 

[Michael6268]

Sounds like a good plan.  My first after holidays project!  Thanks LS.

[mxz583]

Hello is it possible to post more information on installing led's i would like to add this to my tender thanks 

[lionelsoni]

First, if you have it or can get it, look up the article I wrote about LED circuits for the September, 2008, issue of CTT, p. 62.  I did, and it reminded me of a trick that should make the tender-lights project a little easier.  In any case, here's my advice about how to do it:

The two red lights:  Instead of the circuit I posted above, wire the two LEDs in anti-parallel.  That means that the anode of each LED connects to the cathode of the other LED, so the two LEDs light alternately, and each one when conducting protects the other from harmful reverse voltage.  The red-LED pair connects to a single series ballast resistor, and that's the entire red-LED circuit, which connects directly to track voltage.  The resistor value can be computed conservatively as the maximum RMS track voltage multiplied by .45 and divided by the rated forward current of the LED type used.  If this is too bright, the resistance can be increased to make it dimmer, but you should not use a resistor of any smaller value.  The resistor's power rating should be at least the square of the maxumum RMS track voltage, divided by the resistance, but it is a good idea to use an amply higher power rating.

Then the white LED:  For this, use the circuit I posted (but with only one LED of course).  For the voltage value, use not the track voltage but the maximum voltage between the motor brushes.  As above, the resistance should be the RMS voltage multiplied by .45 and divided by the LED's forward current rating.  But, the minimum resistor power rating may be half that given above, that is, half the square of the RMS voltage, divided by the resistance.  As I wrote above, this circuit should connect to the center-rail pickup and to one of the locomotive motor brushes.