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I am attempting to add lighting to an FM Trainmaster dummy (MTH 30-2617-3). Just looking to light the number boards and add the red/green LEDs at the front/rear of the engine.

I have all the pieces to get track voltage (pickup rollers, etc.) and have a “20110 LED Lighting Regulator” to get DC voltage for the lights. I have read a lot about using this regulator for passenger car LED lighting conversions.

I have the 6V grain of wheat bulbs for the number boards (leftovers from previous PS2/3 upgrade kits).

I also have the small red/green 6V LEDs for the front/rear of the engine (CC-0000015 is the MTH p/n).

I have a few questions before I wire and power the lights.

The LEDs must be DC, but are the 6V grain of wheat bulbs also DC voltage?

Is the 20110 LED Lighting Regulator the correct thing to use to feed these 6V lights? What is the DC output voltage of the regulator if it is connected to 18VAC of track power? I do not want to burn-out the LEDs or the grain of wheat bulbs as soon as I put voltage to them!

Thanks in advance. This is my first post here. There is so much knowledge to gain from this community!

Last edited by LOVETJ
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@LOVETJ posted:


...

The LEDs must be DC, but are the 6V grain of wheat bulbs also DC voltage?

The GOW incandescent bulbs can be driven by DC or AC.

Is the 20110 LED Lighting Regulator the correct thing to use to feed these 6V lights?

No.  The 20110 is an awesome contribution to the hobby, but is not appropriate for the matter at hand.  First what you want is a widget that puts out a constant/regulated voltage.  The 20110 delivers a constant/regulated current.

What is the DC output voltage of the regulator if it is connected to 18VAC of track power?

Related to above answer, the 20110 outputs a constant current.  It does this by varying the voltage output until it matches the desired current.  So the DC output voltage can vary by many volts depending on how many LEDs are being driven.

You actually have many options.  Here's one.

6V DC constant voltage

For about $3 (free shipping from Asia), you can get an AC-in, DC-output converter module that delivers a constant voltage.  Just set the converter to a 6V output and then attach your 6V bulbs and 6V LEDs.  The photo above shows a digital voltmeter but that's just to show this converter was adjusted to 6V; presumably you have a DC voltmeter available to adjust the output to 6V DC.

If you are, or will be using DCS, you need to add a 5-cent DCS-inductor between the power pickups and the converter module.   Unfortunately, there are minimum quantities where the DCS inductor ends up being quite expensive if you only need 1!  Both these items are also available more quickly thru Amazon though typically 2x-3x the cost of eBay/Asia.

ac dc buck converter

Now here's something you (or anyone) can answer for me about the CC-0000015.  I am not familiar with this.  But if it's called a 6V light, it needs to have a current-limiting resistor under the black heat shrink as I've circled below.  Is this the case?

6v mth cc-0000015 led ceramic stem

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  • 6V DC constant voltage
  • 6v mth cc-0000015 led ceramic stem
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Last edited by stan2004

@stan2004 or @gunrunnerjohn My AC/DC buck converter finally made it here from overseas and I have a question for either of you. Do I need to use resistors on the 6 volt LEDs if I am giving them 6 volts DC from the convertor? The CC-0000015 harness from MTH has the positives all tied together at the molex connector. So are these LEDs in parallel? Would I need one resistor or four, one for each LED? I just don't want to destroy these LEDs as soon as I put voltage to them. Thanks so much again for your help.

6v%20mth%20cc-0000015%20led%20ceramic%20stem

I am not familiar with that MTH LED harness that is supposedly a 6 Volt LED.

As I asked earlier, can you "feel" a resistor underneath the black heat shrink tubing?

Here's what MIGHT be underneath the black heat shrink.

is there a resistor under the black heatshrink

If that component (a resistor) is present, then it most likely is a 6 Volt LED and you don't have to provide the resistor.

BUT.  To be safe, just adjust the converter output to as low as it will go...probably about 3V or so.  Briefly power up the harness.  I suppose this might involve jamming a small bare wire into the "holes" of the molex connector.  If the LEDs seem dim/dull then continue to crank up the voltage to ~6V.  Does it look "normal"?  I figure everyone looks at LEDs in zillions of devices every day.  You kind of know when an LED is "too bright".

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  • is there a resistor under the black heatshrink
@Alan Mancus posted:

most of the LED's are only 3 volts not six volts! the older engines use gra11in of wheat light and were 6 volts ! if you put 6 volts on a LED you WILL BURN THE DIODE OUT! adjust the buck converter for 3 volts or less depending how bright you want the LED 1

Alan

Alan- MTH advertises this LED harness as 6 volts (CC-0000015) which is why I am confused. I am trying to power a couple 6 volt GOW bulbs off of the same buck converter. This is why I want to run the output of that converter at 6 VDC. I'm trying to determine if I can feed that MTH LED harness at the advertised 6 volts or if I need to add resistors for the LEDs. Thanks for any suggestions you might have.

CC-0000015

As I re-read what you have posted, and looking at the MTH photo, I am almost certain there are tiny resistors at each LED.  Two observations for my reasoning:

(1) why is that black heat shrink so long...about 3/4"...and space is always a premium in mounting lights in an engine.  If it was just the red/blk wires soldered to the LED, then it would not have to be that long.  Hence I think there is a resistor under there.  And,

(2) there are 2 green and 2 red LEDs in parallel (like you've been saying all along ).  if there are no resistors at the LEDs, the red LEDs would steal all the current since they turn on at, say, ~2V whereas the green LEDs turn on at ~3V.  Installing resistors at each LED is standard/simplest method to equalize the 2 colors.

But easy for me to sit back drinking coffee telling you to blow up your LED harness followed by an "oops, my bad" .

So if you have a resistors lying around and want to play it really safe... then insert 1 resistor in-series between your 6V DC power and the molex connector on the harness.  You might have, say, 470 Ohm lying around...or maybe 220 or 1000 (1K) are other common values.  I believe if you do this, the LEDs will all be quite dim.

Or, if you'd have to go out and purchase quantity 1 resistor for this experiment, I'd simply dial down the regulator module to as low as it will go (should be maybe 3V) and then briefly touch the 3V to the harness.  I believe the LEDs will be VERY dim.  Then slowly work up the voltage toward 6V.  If touching 3V to the harness for a fraction of a second causes the LEDs to flash brilliantly, then we need to re-group.   

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@stan2004 posted:

CC-0000015

As I re-read what you have posted, and looking at the MTH photo, I am almost certain there are tiny resistors at each LED.  Two observations for my reasoning:

(1) why is that black heat shrink so long...about 3/4"...and space is always a premium in mounting lights in an engine.  If it was just the red/blk wires soldered to the LED, then it would not have to be that long.  Hence I think there is a resistor under there.  And,

(2) there are 2 green and 2 red LEDs in parallel (like you've been saying all along ).  if there are no resistors at the LEDs, the red LEDs would steal all the current since they turn on at, say, ~2V whereas the green LEDs turn on at ~3V.  Installing resistors at each LED is standard/simplest method to equalize the 2 colors.

But easy for me to sit back drinking coffee telling you to blow up your LED harness followed by an "oops, my bad" .

So if you have a resistors lying around and want to play it really safe... then insert 1 resistor in-series between your 6V DC power and the molex connector on the harness.  You might have, say, 470 Ohm lying around...or maybe 220 or 1000 (1K) are other common values.  I believe if you do this, the LEDs will all be quite dim.

Or, if you'd have to go out and purchase quantity 1 resistor for this experiment, I'd simply dial down the regulator module to as low as it will go (should be maybe 3V) and then briefly touch the 3V to the harness.  I believe the LEDs will be VERY dim.  Then slowly work up the voltage toward 6V.  If touching 3V to the harness for a fraction of a second causes the LEDs to flash brilliantly, then we need to re-group.   

Thank you for all of your time that you are spending with me on this. This forum is great!

I guess the easiest thing to do will be to delicately remove the heat shrink near the LEDS and find out what is under there. I will keep you posted, thanks.

@LOVETJ posted:

@stan2004 I cannot feel any resistors under the heat shrink. What value resistor should I try? Since all of the positive leads are bundled together at the molex connector would I need just one resistor or four, one for each LED? Thanks for all of your help with this.

There are no resistors under that heatsink, those are series connected LED's and they're used in a current limited circuit.

Never mind, I'm thinking of a different harness!  Sorry for the mis-information!

Last edited by gunrunnerjohn

CC-0000062

Actually that caused me to scrounge for a photo of what I think you may be referring to.  To my earlier observation about heat shrink length:

The heat shrink AT THE LEDs in this harness is much shorter (about 1/2") than the 4-LED version under discussion.  This suggests there is NO resistor on this 2-LED version.  OTOH, the heat shrink length AT THE 2-pin CONNECTOR is much larger...suggesting something is "going on" underneath!  I believe this is where your series connection is made.  On the 4-LED version there is no such heat shrink at the connector and you see the red and black wires going right thru.

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@stan2004 posted:

CC-0000062

Actually that caused me to scrounge for a photo of what I think you may be referring to.  To my earlier observation about heat shrink length:

The heat shrink AT THE LEDs in this harness is much shorter (about 1/2") than the 4-LED version under discussion.  This suggests there is NO resistor on this 2-LED version.  OTOH, the heat shrink length AT THE 2-pin CONNECTOR is much larger...suggesting something is "going on" underneath!  I believe this is where your series connection is made.  On the 4-LED version there is no such heat shrink at the connector and you see the red and black wires going right thru.

@stan2004 and @gunrunnerjohn I carefully removed the heat shrink. There are no resistors. I agree that these LEDs are in parallel and must be fed by a current limited circuit in their original home (FM Trainmaster).

Can I feed the four GOW bulbs for the number boards directly from the buck converter at 6 VDC and also feed the “20110 LED Lighting Regulator” 6 VDC from the coverter and have the current regulator feed the four LEDs for the marker lights? Or just use the buck converter for the GOW bulbs and use the “20110 LED Lighting Regulator” to power the LEDs?

Here is the pic of the harness with the heat shrink removed.

LED Harness

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  • LED Harness
Last edited by LOVETJ

I'd rewire them in that case.  The green LED's light at a higher voltage than the red LED's.  So, with green and red in parallel, it's common to see the red ones light and the green ones not light or be very dim.  MTH did this on their subway cars with predictable results.  I ended up rewiring a couple of sets of cars for a customer because of the design screwup with the lights, the green ones didn't light!

DUH!!! I wonder why?

Last edited by gunrunnerjohn

I'd rewire them in that case.  The green LED's light at a higher voltage than the red LED's.  So, with green and red in parallel, it's common to see the red ones light and the green ones not light or be very dim.  MTH did this on their subway cars with predictable results.  I ended up rewiring a couple of sets of cars for a customer because of the design screwup with the lights, the green ones didn't light!

DUH!!! I wonder why?

Do you have any suggestions on rewiring them? Can I feed them with the “20110 LED Lighting Regulator”? Would just the green ones need resistors? Thanks.

I can't believe my own eyes!   I don't understand how they can call this a 6V light.

I think the simplest solution is to cut the harness in two places as shown.  In each cut, splice in a resistor (value to be supplied if this is acceptable).  More complicated/involved solutions would be to make 4 cuts and splice in 4 resistors...or re-wire the harness for a different series/parallel configuration, and so on.

CC-0000015

Do you have any resistors at all lying around???

This method would allow you to power the harness with the 6V regulator module.

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Last edited by stan2004

Any time you put dissimilar LED's in parallel, you need balancing resistors to insure that the higher voltage ones aren't starved for power.  If you have a high enough voltage available, it's possible to run them in series, then you can just use a single current limiting resistor for the whole string.  If you're running from track power and using the 20110 LED Lighting Regulator, no resistors needed, just wire the LED's all in series and adjust the intensity with the pot on the regulator board.  The 6V lights, OTOH, will need their own source of power, which from previous posts here I think you have covered with your adjustable voltage module.

No argument there. Since he already has your LED regulator board in-hand, that only requires re-wiring the harness but no additional out-of-pocket cost.  Sounds like a plan.

I was suggesting an approach using just the existing 6V regulator output that is already driving (apparently) some existing 6V bulbs.  This method would require soldering in 2 resistors which would involve some out-of-pocket cash if his parts cupboard is bare.

But as a completely separate question, what was MTH thinking calling their CC-0000015 a 6V light?

I see your comment about fixing subway cars that apparently had this incestuous relationship between red and green LEDs.

OTOH I can see where there might be applications where one would want to plug in an LED based 6V light into the molex connector of a PS2 or PS3/2 LAMP output (headlight, tail-light, interior light, etc.) that is meant for a 6V incandescent bulb(s).  This would give you DCS on/off command-control of the 2 red and 2 green LEDs.

Well, if nothing else, maybe all these buzzwords (let me throw in a couple more below) will get caught by a future "search" on this topic!

Two series connected red ceramic stem LEDs on molex harness: CC-0000062

Last edited by stan2004

No resistors needed Stan, if he has two greens in parallel and two red's in parallel, he can just put those in series/parallel and use the LED regulator board.

When you say series/parallel do you mean connect the red (+) of the RED LEDs to the (+) 20110 LED Lighting Regulator, then connect the black (-) of the RED LEDs to the red (+) of the GRN LEDS and then finally the black (-) of the GRN LEDs back to the (-) input of the regulator? No resistors needed? Similar to the diagram below?

Diagram

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  • Diagram

To beat a dead horse, I don't understand how/why MTH calls their part number CC-0000015 a "6V" bulb!

mth cc-0000015

So let me repeat the part number here a few times in hopes that a "search engine" will find this thread to hopefully save someone else grief, headache, or angst in the future!

CC-000015 CC0000015

CC-000015 CC0000015

CC-000015 CC0000015

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  • mth cc-0000015

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