# Question about 19v lamps while moving to DCC



## Chata86 (Dec 5, 2010)

My goal is to eliminate all of my wiring around the track as I switch to DCC. One obvious first step is to ditch all the EPL wiring and stuff decoders into the EPL switch motors. At that point the only wiring I'll be left with is the ambient lighting in my buildings and semaphores. I believe these are all 19V lamps powered by 18VAC from my analog power supply. I've been reading that when switching to DCC, I will be running 25VDC on the track - so I'll need to address that higher voltage for the lamps. One person suggested "adding diodes" to me. I've found some websites that discuss current limiting resistors for LEDs, but nothing for lamps. Any suggestions?


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## Trains West (Oct 4, 2008)

whos dcc system ? most do not go over 19 volts ......

and how many lamps ? just worndering about how much current you will be drawing from the system


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## Greg Elmassian (Jan 3, 2008)

Well, while LEDs operate on current, lamps operate on voltage. 

Controlling current is easily done with resistors, you can "set" the max current. 

Lamps operate on voltage, so you need to "set" the max voltage. 

Diodes have a fixed voltage drop of about .7 volts, so if you want to drop it from 24 to 19, you need 5 volts 

Yes some diodes in series can drop the voltage, and you will want to drop it, 19v lamps were not chosen assuming a constant track voltage, but a much lower voltage... the marker lamps in my Aristo steamers are all 18v, and are all burning out. 

You probably won't be running over 24 volts, but that's what I run so I speak from experience here... 

so 7 diodes would drop 4.9 volts, so probably 8 diodes in series... they can be really cheap 1 amp or less diodes you buy in bulk. 

Regards, Greg


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## Axel Tillmann (Jan 10, 2008)

Here is the most important fact, try to be consistent, or at least make datasheets for each engine, so that you can look up what you did. If you are from engine to engine consistant you will be able to rely on memory for any changes/repairs.... afterwards. Or you will always have to use the datasheets to look up the info.

Stay away from regulating the voltage thorugh the function output (PWM). Always use proper input voltage. Some higher end DCC boards have multiple voltage outputs (e.g. 5V, 10V, and adjustable 1.5V-trackpower), some HO style decoders have dedicated LED outputs.

I run my track also at +28V in order to set reliably my decoder to MAX voltage of 18V throughout my entire track, inlcduing the reversing loops. No matter where I am in the layout I have at least 20V and that give enough room for the MaxV to be 18V.

I would stay away to current limiting resitors becuase they have to be 1W to 2W type since the bulbs have a much higher current. Better to use lower voltage (e.g 5V output with 5V bulbs).


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## Chata86 (Dec 5, 2010)

Greg, I was looking at that current limiting part on your webpage. I couldn't find it on digikey. I had been considering switching to LEDs. Does anyone make an LED with integrated 10mA current limiting - that'd be hand for scale modeling where size is of concern. 

Anyway, for lamps - it sounds like you're recommending adding several diodes in series with the lamp to get the voltage down for the 19V lamps. Heck, it sounds like the first modification to any Aristo steamer should be adding a diode in the lamp circuit to give them some longevity. I prefer my lamps to be a little dimmer anyway.

Thanks!


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## Dan Pierce (Jan 2, 2008)

Myself, I would not use DCC track power for the buildings. It may be easy as the track goes everywhere, but a separate source would keep the load off the DCC system. 

If there is a short, there are too many places where this can happen with lights connected to the track. 

I run 12 volt low voltage (malibu power packs) around my layout and use the 4 watt bulbs in the light posts. Cost of a lighting kit in the fall was $10 when stores dumped them. That was a power pack and 10 lights. The posts keep my buildings from moving in the wind!!


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## Greg Elmassian (Jan 3, 2008)

The CL2 is made by Supertex. 

Try Mouser:

*http://www.mouser.com/Search/Refine...pertex+cl2* 


Greg


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## ddevoto (Jan 22, 2008)

If you're considering LEDs check the website below. They have "all in one" LEDs ( rectifier + resistor) for DCC at a very low price. 

http://www.modeltrainsoftware.com/ledlights1.html


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## Chata86 (Dec 5, 2010)

Thanks for sending that. Their welding kit light is pretty interesting too!

I don't think the T3/4,T1, T1-3/4 LEDs would work for replacement in an LGB semaphore - since they would emit light upwards, not forward through the lens. Perhaps the chip LEDs with DCC option though.

Their universal LED kit is supposedly viable for track power, but only goes up to 19V? That won't work.


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## ddevoto (Jan 22, 2008)

One more thing they say 7 to 19V. on the website but are actually 8 to 25V.


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## Chata86 (Dec 5, 2010)

http://www.youtube.com/danstrains
nice layout btw!


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## ddevoto (Jan 22, 2008)

Thank you, lots O fun!


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## Cougar Rock Rail (Jan 2, 2008)

I believe these are all 19V lamps powered by 18VAC from my analog power supply. I've been reading that when switching to DCC, I will be running 25VDC on the track - so I'll need to address that higher voltage for the lamps. One person suggested "adding diodes" to me. I've found some websites that discuss current limiting resistors for LEDs, but nothing for lamps. Any suggestions?

I would suggest you change to the 24V bulbs that Massoth sells--they are direct replacements for the LGB lamps. I'm not sure why(or even how) you're running 25V on the tracks but Zimo and Massoth systems will let you adjust the track voltage. I run the LGB MTSIII which gives me 22.5V at the tracks so that's why I use the 24V bulbs.

Keith


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## Axel Tillmann (Jan 10, 2008)

Dear Keith:

Just for completion of your knowledge, LGB, Proline (hence TrainLi) we all have 24V plugins in stock. But of course that exchange is only needed if your decoder doesn't have a 5V low voltage output


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## Trains West (Oct 4, 2008)

the decoder does not need to have a 5 volt output the lgb board will have it if it has 5 volt lights


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## Axel Tillmann (Jan 10, 2008)

Only if you keep the LGB board with is not a given in all installtions


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## Greg Elmassian (Jan 3, 2008)

The original post:

My goal is to eliminate all of my wiring around the track as I switch to DCC. One obvious first step is to *ditch all the EPL wiring *and stuff decoders into the EPL switch motors. At that point* the only wiring I'll be left with is the ambient lighting in my buildings and semaphores.* I believe these are all 19V lamps powered by 18VAC from my analog power supply. I've been reading that when switching to DCC, I will be running 25VDC on the track - so I'll need to address that higher voltage for the lamps. One person suggested "adding diodes" to me. I've found some websites that discuss current limiting resistors for LEDs, but nothing for lamps. Any suggestions? 


The first bolded part says to me the old LGB circuitry is history.

The second one says the same, or that there's just bulbs and no decoders...

Don't see how we are finding any 5v supplies on any sound boards... did not see any sound boards mentioned...


Greg


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## Chata86 (Dec 5, 2010)

Correct. It probably goes without saying that while I'm ripping out all the EPL wiring I'm also converting all the switches and semaphores over to DCC control. My concern is for the factory specification bulbs around the layout and what repercussion there might be in moving them to track power (in an effort to remove even more wiring) knowing that the track could be near 24V.

It sounds like the 24V lamps are the ticket. Thanks!


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## Greg Elmassian (Jan 3, 2008)

The one thing I would say about that is that you can start pulling a significant amount of current depending on the lamps you use, get the milliampere rating and add it up. 

Since lamps usually draw several times what LEDs do, you may want to total up what you are planning and see if you are going to significantly affect the current to the rails.

Another hint, in a building, with 24v supply, you can put several LEDs in series and still only draw 20 milliamperes, another power savings. 


Greg


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## ddevoto (Jan 22, 2008)

Posted By ddevoto on 28 Nov 2011 09:07 AM 
One more thing they say 7 to 19V. on the website but are actually 8 to 25V. I really think LEDs are the way to go. You have color options as well as low power usage. I have had no trouble running them at 22.5v. from Model Train Software.


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