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Attached is a PDF describing a way to convert LionChief passenger cars from incandescent lighting to LED lighting.  (In this example, Santa Fe streamline passenger cars.)  It reduces current draw from about 154 mA down to about 12 mA.  Also, you won't have to change burned out incandescent bulbs anymore.

Lionel has produced the cars with both incandescent and LED lighting.  Lionel's LED lighting approach has a small circuit board at each end that includes a keep alive capacitance.  Each truck independently powers a board, so the boards are in parallel and their total current draw is about 36 mA.  Pretty good, but not as low as this conversion.

While the conversion does not have a "keep alive" capacitance, it does wire the trucks in parallel so all wheels and rollers are used to power all of the LEDs.  This should go a long way to prevent flickering from dirty track.

The  conversion is a bit physically crude, but it is simple and works.

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Describes converting a LionChief passenger car from incandescent to LED lighting
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@jjm posted:

Thanks.  The pics are very helpful.  In addition to the LED part number, would you supply part number references for the other components?

The other parts (diode and resistor) are extremely common items available from many sources.

The diode is a 1N4001 as shown.  The particular ones I bought were on Amazon as "(Pack of 100 Pieces) Chanzon 1N4001 Rectifier Diode 1A 50V DO-41 (DO-204AL) Axial".  You can also get these from electronics distributors like Mouser Electronics or Digi-Key.  Many other diodes will also work.  For example, you can use a 1N4001, 1N4002, 1N4003, 1N4004, 1N4005, 1N4006, or 1N4007 as each of those simply has a higher voltage rating so they are all suitable.

The resistor I used is a 1% tolerance "metal film" type from an assortment I bought long ago, also from Amazon, as "ELEGOO 17 Values 1% Resistor Kit Assortment, 0 Ohm-1M Ohm (Pack of 525) RoHS Compliant".  But you don't need a 1% resistor.  A cheap carbon resistor will be just fine.  Again, you can get such resistors from many sources such as Mouser Electronics or Digi-Key or Amazon.  (In case anyone wonders why there is a thing such as a "0 Ohm resistor", they are used in place of jumper wires.  More commonly seen in situations where circuit boards have parts loaded by machine - the machine knows how to load something shaped like a resistor and they can be provided on long rolls like regular resistors.)

The wire is another staple item and in this case I just bought some from the local hobby shop that had a fairly small quantity in an assortment of a few colors in a bag.  The bag is labeled "Hobby Unlimited" with their part #VHB-AD-5697.  I'm not sure you will be able to find that particular package.  But any 26 gauge stranded wire (or even other sizes) will do.  Such wire is available at Amazon, Mouser Electronics, Digi-Key, and elsewhere.  And you can certainly use smaller wire such as 28 gauge or even 30 gauge.  Those smaller sizes are typically used for wiring DCC decoders such as in HO locomotives so can often be found in small quantities in model train shops.  You can buy 30 gauge wire by Miniatronics and others from from Walthers and that would work fine as the current draw is so small.  But really small wire is more delicate to work with and a bit pricey.  So I used 26 gauge for this.  If you search for "26 gauge wire" on Amazon you will find many choices.

@jjm posted:

Thanks, again, Chuck.  I am fine with following instructions (especially pics and vids), but not as well schooled in the flexibility around what is acceptable tolerance in component parts!

On something like this, even though a simple circuit, if not very familiar with such things it can help to first rig up a quick test (before soldering anything).  I've got over 50 years of electronics experience and still do this.  (I believe in the adage, "One test is worth a thousand opinions".)  In this case, I just used a bunch of alligator clip leads to connect the parts together and a bench power supply.  You could also attach to track voltage, the output of a LionChief Wall pack directly, or whatever will produce about 18 volts DC.  There are various "alligator clip test leads" usually in a package of 10, on Amazon and elsewhere.  I find them very useful.  Below is a photo of my "mad scientist" set up where I first tested this - mainly to pick a resistor value for a brightness level I liked and to measure the current to make sure it was what I expected.  You can see the four LEDs lit up and to the right of them the resistor and to the right of that the diode and to the right of that a power supply.  Out of picture range to the left is a multimeter, also connected in series, measuring current.

LED Lighting Mod 5 - LoRes 

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  • LED Lighting Mod 5 - LoRes

Thanks for those links to other projects.  I was aware of many ways to do it.  My goal was what was the cheapest most simple way.  Not shooting for elegant here.  And to use through-hole LEDs in a way that provided halfway even lighting even with their directionality.  These cars are part of a project where I am building a toy train layout (about 80 sq. feet of layout surface in a dogbone configuration) for a local Exploration Discovery Center for children.  (Previously I made a smaller one for the San Luis Obispo Railroad Museum.)  Since I'm running two trains from one Wall Pack, and probably a 36 watt one, I didn't want power wasted on incandescent bulbs.  I also didn't want anybody saddled with replacing burned out bulbs because I would expect some ruined roofs on cars by the time somebody figured out how to break into these things.  I also wanted lighting that would likely last forever.  I'm using 30 mA rated LEDs at 12 mA so they should last forever and then some.  I also went with CREE LED's for top quality instead of nameless Chinese ones.  In fact, I was involved in the control system design, software, and support of some of the machinery CREE uses to manufacture the things.

I'm thinking the combination of (cheapest,Cree,thru-hole), might have to give up on one of those.

Design and have made a long thin circuit board? And populate the board yourself?

I bought two PCB from Royz Troyz for brass Sunset passenger cars, they have thru hole LEDS, maybe buy boards and replace the LEDs?

I didn't use a circuit board.  The LED leads merely go through some holes in existing plastic cross structures to keep them in place.  The LEDs (used 4) were 21 cents each, the diode 6 cents, and the resistor 3 cents.  That's a grand total of 93 cents for the parts.  (Not counting whatever a little hookup wire cost.)  I think anybody would be pretty hard pressed to do it for much less.  Unless they dropped the design to 2 LEDs and lowered the resistance (would then have to be a 1/2 watt one probably) and in that case it could be done for 50 cents.  Or perhaps buy really cheapie LEDs.  But I got more even lighting using 4 LEDs oriented like they are.

There is a package offered on Amazon that includes LEDs and resistors.  Would these work along with the diodes listed below?

LED & resistor Specs:

  • Product Overview: 100 pcs LED Diodes + 100 pcs Resistors
  • Product Features: Warm White Lights / 3mm Diffused Round Lens / White Lens
  • Product Parameters: 29mm Long Lead / DC 3.0V-3.2V (IF=20mA) / 0.06 Watts / 2pin / DIP LEDs
  • Product Parameters: Luminance Brighter Up To +20% / Wavelength 1200K-3500K / 120° Viewing Angle / Single LED Diodes Wight: 0.16g
  • Accessories: 100pcs 430ohm (For DC 6-12V) 1/4 Watt Metal Film Resistors Include / ±1% Tolerance


Diodes: (Pack of 100 Pieces) Chanzon 1N4001 Rectifier Diode 1A 50V DO-41 (DO-204AL) Axial 4001 IN4001 1 Amp 50 Volt Electronic Silicon Doorbell Diodes

@jjm posted:

There is a package offered on Amazon that includes LEDs and resistors.  Would these work along with the diodes listed below?

LED & resistor Specs:

  • Product Overview: 100 pcs LED Diodes + 100 pcs Resistors
  • Product Features: Warm White Lights / 3mm Diffused Round Lens / White Lens
  • Product Parameters: 29mm Long Lead / DC 3.0V-3.2V (IF=20mA) / 0.06 Watts / 2pin / DIP LEDs
  • Product Parameters: Luminance Brighter Up To +20% / Wavelength 1200K-3500K / 120° Viewing Angle / Single LED Diodes Wight: 0.16g
  • Accessories: 100pcs 430ohm (For DC 6-12V) 1/4 Watt Metal Film Resistors Include / ±1% Tolerance


Diodes: (Pack of 100 Pieces) Chanzon 1N4001 Rectifier Diode 1A 50V DO-41 (DO-204AL) Axial 4001 IN4001 1 Amp 50 Volt Electronic Silicon Doorbell Diodes

That all looks like it should work.  Current will be just a little higher with a 430 ohm versus a 470 ohm, but not much.  About 12.6 mA.  And only about 0.07 watts for the resistor which is well below the 1/4 watt resistor rating.  As you have noticed on Amazon, such parts, especially the Chinese ones you mentioned, hardly cost anything.  With 20 mA rated LEDs, that should be fine.  But I have some reliability problems with some of the cheap LEDs.

If you want to know how the "math" works.  First, there will an approximate 3 volt drop across each LED and approximate 0.6 volt drop across the diode.  With four LEDs and one diode that is a 12.6 volt drop total.  Assuming an 18 volt supply, the voltage across the resistor is whatever voltage is left which is 18 V - 12.6 V = 5.4 V.

Current is from Ohms law arranged as I = E/R (current is voltage divided by resistance) and is 5.4 V / 430 ohm = 12.6 mA.

Power dissipated by the resistor will be I squared times R or 0.0126 amp x 0.0126 amp x 430 ohm = 0.068 watts,  (Meaning it shouldn't be able to melt a plastic roof - but it is always good to temporarily connect a circuit idea together on the bench and test it first.)

One problem with any scheme which does not have the keep alive capacitor is 60hz flicker. The random flicker caused by uneven conduction to the pickup rollers does not bother me. However 60hz flicker drives me nuts and makes my eyes ache. Strange thing about 60hz flicker many people cannot even see it but if you can it is very hard on the eyes.  If you can tolerate the 60hz then Chucks scheme is great. Though there is an even simpler scheme just string together 10-12 leds they will work fine no resistor no diode.  Just add or subtract till you have the brightness you want. Then watch the 60hz till your eyeballs explode and your head cracks.  Attached photo 9 led, transformer set to 18v, no resistor no diode.  If you run DCS you better add a 22uh choke to the string of leds, Chucks scheme also.            j        

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Last edited by JohnActon
@JohnActon posted:

One problem with any scheme which does not have the keep alive capacitor is 60hz flicker. The random flicker caused by uneven conduction to the pickup rollers does not bother me. However 60hz flicker drives me nuts and makes my eyes ache. Strange thing about 60hz flicker many people cannot even see it but if you can it is very hard on the eyes.  If you can tolerate the 60hz then Chucks scheme is great. Though there is an even simpler scheme just string together 10-12 leds they will work fine no resistor no diode.  Just add or subtract till you have the brightness you want. Then watch the 60hz till your eyeballs explode and your head cracks.  Attached photo 9 led, transformer set to 18v, no resistor no diode.  If you run DCS you better add a 22uh choke to the string of leds, Chucks scheme also.            j       

You can get away with doing what you are doing.  But just so people know, you should generally avoid any situation that reverse biases an LED.  it is typical that they be safe up to about 5 volts reverse bias, but might have the breakover voltage at 12 to 20 volts at which point the LED is destroyed.  Also, a resistor would normally be used for limiting current to a safe value.  What is happening with the string of diodes is sort of a "workaround" where there are enough forward voltage drops of the series LEDs so there isn't enough voltage across any LED for it to overcurrent.  And the reverse bias is divided between all the LED's (theoretically anyway) so any one LED shouldn't see a very high reverse voltage.

@Chuck K. posted:

You can get away with doing what you are doing.  But just so people know, you should generally avoid any situation that reverse biases an LED.  it is typical that they be safe up to about 5 volts reverse bias, but might have the breakover voltage at 12 to 20 volts at which point the LED is destroyed.  Also, a resistor would normally be used for limiting current to a safe value.  What is happening with the string of diodes is sort of a "workaround" where there are enough forward voltage drops of the series LEDs so there isn't enough voltage across any LED for it to overcurrent.  And the reverse bias is divided between all the LED's (theoretically anyway) so any one LED shouldn't see a very high reverse voltage.

That's why you need to start around 8 leds for 18v.  That will be as bright as you get add more leds to dim it down. But like I said I don't use this I don't like the 60hz. Three years ago I hooked those in my photo up to the transformer and left them on non stop for nearly two months. The passenger cars I gave to the grandkids all have this scheme for lighting.  It's stable.           j

Here's a link to a OSHPark project to buy constant current LED control board: Passenger Car Lighting Board on OSHPark.

This small board supplies flicker-free operation with adjustable intensity and DCS protection.  Build cost is around $2/ea, maybe less with off-shore components.  This is based directly on my commercial LED Lighting Regulator and has the same functionality.  Many people have built these and are using them.  If you're looking for a quantity more than a handful, going off-shore to one of the many PCB houses would probably be warranted to keep the costs down.

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I have used John’s lighting kits in all my passenger cars.  I just completed this small set.  I swapped out a truck to light the baggage car as you really only need one truck with pickups when using his kit. The baggage car and the observation car have only one pickup truck. They are moving at slow speed through an 072 switch.

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