So I have this idea and wonder if it can be built.

[Lemosteam]

As I finish my layout extension, and from the start it's purpose was intended to be a photo module for outdoor and remote photography, particularly at night. 

This is what I am wondering based on these givens and druthers listed below;

-DCC control
   -No loco running
   -Loco and passenger car lighting only
-Battery operated only
-Compact, small tackle box type system
-4 powered tracks ( @peteski ) to light the cars
-12v or 18v Cordless power tool-type battery connection if possible
-Loconet connection?

Can a battery operated DCC controller be constructed that is powerful enough to only power four tracks, light a loco(s) headlight(s), and several passenger cars?

Would I really need a complete command station for this or could a box be made to only transmit the lighting packets to the loco decoder, assuming the passenger cars would light up from battery track power.

Is it always required to address each loco as well?

Could the system use an Arduino to "read" each loco's decoder and allow control (micro JMRI)?

Thoughts, ideas?

[peteski]

Your request does not seem to be clear as to whether you want decoders in the cars, or just power them from the DCC (packet) track power.

I don't believe that there is such a system where only lighting/functon packets would be sent. Not even sure why that would be needed.  The power to all the decoder-equipped vehicles (locos, illuminated cars, cabooses) is carried by the packets sent through the track, many times a second.  The power supply part of the decoders doesn't care what types of packets the power comes from.  To simplify things, all the decoders can be programmed for the same address, or if you want to control individual pieces of rolling stock, program them  for different addresses,

to me there doesn't seem to be a reason to design a dedicated DCC system just for lighting.  Just use one of the entry level DCC systems like Digitrax Zephyr, NCE Power Cab, or several other less known command stations, to just power all the tracks. 

Most of the entry-level DCC systems come with a wall-wart type of power supply which can easily be replaced with a battery.  Make sure to install a fuse near the battery so protect from any unforeseen accidental shorts. Unlike wall-warts, a battery can supply very high current and if there was s short, it can melt the wiring.  A fuse near the battery will protect from any such incidents.

As an owner of one, I think that NCE Power Cab would be ideally suited for this project.  It is a fully-featured DCC system in a handheld throttle (easily fits in a tackle box), can supply 2A of current to the track (likely more than enough for your needs), and is is quite intuitive to learn and use.  But if you need LocoNet then a Digitrax system would be needed.  OR one of the less kown DCC systems which can interface with LocoNet. Number of tracks is irrelevant - only the total amount of needed amperage is what counts.

As far as the motor in the loco goes, you can keep the original mobile decoders and just keep the speed dialed at zero (stopped). To be sure the model doesn't move, you can also disconnect the motor from the decoder.  Or you can likely set the speed table in the decoder to all zeros (never tried that).  Or install function-only decoders in the loco.  Alternately you can just disconnect the motor leads/wires from the decoder. That way it is guaranteed the loco will not move.

[Lemosteam]

Your request does not seem to be clear as to whether you want decoders in the cars, or just power them from the DCC (packet) track power.

I don't believe that there is such a system where only lighting/functon packets would be sent. Not even sure why that would be needed.  The power to all the decoder-equipped vehicles (locos, illuminated cars, cabooses) is carried by the packets sent through the track, many times a second.  The power supply part of the decoders doesn't care what types of packets the power comes from.  To simplify things, all the decoders can be programmed for the same address, or if you want to control individual pieces of rolling stock, program them  for different addresses,

to me there doesn't seem to be a reason to design a dedicated DCC system just for lighting.  Just use one of the entry level DCC systems like Digitrax Zephyr, NCE Power Cab, or several other less known command stations, to just power all the tracks. 

Most of the entry-level DCC systems come with a wall-wart type of power supply which can easily be replaced with a battery.  Make sure to install a fuse near the battery so protect from any unforeseen accidental shorts. Unlike wall-warts, a battery can supply very high current and if there was s short, it can melt the wiring.  A fuse near the battery will protect from any such incidents.

As an owner of one, I think that NCE Power Cab would be ideally suited for this project.  It is a fully-featured DCC system in a handheld throttle (easily fits in a tackle box), can supply 2A of current to the track (likely more than enough for your needs), and is is quite intuitive to learn and use.  But if you need LocoNet then a Digitrax system would be needed.  OR one of the less kown DCC systems which can interface with LocoNet. Number of tracks is irrelevant - only the total amount of needed amperage is what counts.

As far as the motor in the loco goes, you can keep the original mobile decoders and just keep the speed dialed at zero (stopped). To be sure the model doesn't move, you can also disconnect the motor from the decoder.  Or you can likely set the speed table in the decoder to all zeros (never tried that).  Or install function-only decoders in the loco.  Alternately you can just disconnect the motor leads/wires from the decoder. That way it is guaranteed the loco will not move.

I am not dropping $200+ into this, I do not have the funds to pay for a Zephyr or NCE (I think you are on their payroll  ).  I want to build this as inexpensively as possible and do something different for the fun.  So no new decoders in the locos or cars, etc. or reprogramming of decoders.

I don't even want to RISK driving a consist off the end of the module, so I want to bypass the throttle altogether, i.e., not even a CHANCE that the loco could move.

[peteski]

That's why I described multiple ways to immobilize a loco.  Disconnecting or removing a motor is the most reliable way to prevent a loco from moving.

Sorry that I wasted my time posting my message. Best of luck with your project.   
Curious what other brilliant DCC ideas others will come up with.

[Scottl]

DCC-Ex can do this.  Easy DIY insrructions

[turbowhiz]

The super cheap option:

You could just put 12V DC to the tracks, and your DCC lighting should just work; You IMPARTIVELY need to disable DC compatibility on any locomotive as it will just runaway full speed, but that is a plain good idea if you’re using anything DCC on an open-ended short section regardless, in case whatever command station craps out and the DCC signal stops being generated the same result will happen. I always disable DC operation on DCC locomotives for this reason. (Maybe because I’ve always used homebrew command stations, built my own in 1996, but anyhow…)

However, you won’t obviously be able to control anything, so just depending on the previous state/decoder behavior you might not get desired results.

Your probably better option:

I’d build a DCC-EX setup for this.

You can assemble Arduino+Motor Shield+ESP for a lot less money than a commercial option. The DCC-EX setup/configuration is well documented and fairly straightforward.

There is a warning about powering the Arduino with >12V input from the motor shield. Just don’t feed the motor shield with more than 12V, and you’re golden. It simplifies the setup for your remote use case. Supply 12V DC or a little less to the motor shield, and the Arduino/ESP are also powered, making it an easy setup. Get 12V DC from whatever battery setup you want.

Control this setup using a mobile device connected to the wifi using a throttle app, and you’re done. That is super easy, and for basic function control a superior UI then any commercial command station anyhow.

This is my "show demo table" setup. Cheap/easy/effective.

(As a point of clarify, there is no such thing as a DCC “lighting” packet)

[Sokramiketes]

Here's another vote for DCC-Ex.  There's probably a cheaper way, but the DCC-Ex route makes sure you can deliver what you're trying to do without DCC becoming your new hobby. 

[Lemosteam]

That's why I described multiple ways to immobilize a loco.  Disconnecting or removing a motor is the most reliable way to prevent a loco from moving.

Sorry that I wasted my time posting my message. Best of luck with your project.   
Curious what other brilliant DCC ideas others will come up with.

@peteski , you did not waste your time. I appreciated the comment. I guess I thought I wrote it in such a way as to imply homemade.

What I am looking to accomplish is pulling the module out, setting it up, connecting it quickly (and your point regarding battery voltage is well taken) turning on the lights and taking pictures. Not sure I could do that quickly with a multi device modular (and still quite expensive) off the shelf system.

Looking at the DCC-EX, it may be quite a viable setup for my needs, although, I may have to settle for using the throttle.

[peteski]

@peteski , you did not waste your time. I appreciated the comment. I guess I thought I wrote it in such a way as to imply homemade.

What I am looking to accomplish is pulling the module out, setting it up, connecting it quickly (and your point regarding battery voltage is well taken) turning on the lights and taking pictures. Not sure I could do that quickly with a multi device modular (and still quite expensive) off the shelf system.

Looking at the DCC-EX, it may be quite a viable setup for my needs, although, I may have to settle for using the throttle.

Fair enough. 
I'm still unclear about your lighting requirements.
Let me see if I understand this correctly.  You don't want to put DCC decoders in every illuminated car, right?  Just standard lighting circuit powered from the track?  DCC signal is only needed for the locomotive headlights? And you don't even need them to tun on or off - just continuously stay turned on for the photo session?

[Mike C]

   @Lemosteam    Ok so the car lights are easy , just use a 9 v battery .  The loco headlights will need some type of DCC system to turn them on .  However , how are you at Photoshop ? Could you just photoshop the headlight ?     Mike

[Lemosteam]

Fair enough. 
I'm still unclear about your lighting requirements.
Let me see if I understand this correctly.  You don't want to put DCC decoders in every illuminated car, right?  Just standard lighting circuit powered from the track?  DCC signal is only needed for the locomotive headlights? And you don't even need them to tun on or off - just continuously stay turned on for the photo session?

Yes. The cars are already track powered by DCD (or DC).

Just don’t want to have any movement.

[Lemosteam]

   @Lemosteam    Ok so the car lights are easy , just use a 9 v battery .  The loco headlights will need some type of DCC system to turn them on .  However , how are you at Photoshop ? Could you just photoshop the headlight ?     Mike

I got no skillz for that! Lol.

[turbowhiz]

   @Lemosteam    Ok so the car lights are easy , just use a 9 v battery . The loco headlights will need some type of DCC system to turn them on . 

No, no they don't. They turn on just fine with a 9V battery.... At least here with a Loksound 5 in some random loco I just picked off the layout to prove the point. And yeah, in this case, the sound turns on too. I'm an ESU guy, although I also tried the one and only loco with a dinotrax decoder in my fleet and it worked perfectly too..... Reverse the polarity of the 9V if the wrong lights come on in that case.

Like I previously mentioned, just disable the DC operation..... A very good idea anyhow in my opinion, especially if the concern if the locos are going to accidentally run. Its arguably the "safest" option given the "I don't want a throttle to accidently run stuff" requirement.

The cheap option I previously mentioned is entirely viable.

[peteski]

Yes. The cars are already track powered by DCD (or DC).

Just don’t want to have any movement.

Ok, so you will need some sort of DCC command station/booster which will be capable of addressing the decoder in the loco.  I have never worked with DCC-EX, but after looking at the website it doesn't' seem las easy as just buying a low-end DCC system.  Looks to me like some learning curve is required to get all the things assembled into a working DCC system.  Others more familiar with it will likely give you some help.

I also strongly agree with other comments that it will still be safer to put some mechanical stops at the track ends.  Never trust electronics. Maybe just a piece of clear acrylic?

[peteski]

No, no they don't. They turn on just fine with a 9V battery.... At least here with a Loksound 5 in some random loco I just picked off the layout to prove the point. And yeah, in this case, the sound turns on too. I'm an ESU guy, although I also tried the one and only loco with a dinotrax decoder in my fleet and it worked perfectly too..... Reverse the polarity of the 9V if the wrong lights come on in that case.

Like I previously mentioned, just disable the DC operation..... A very good idea anyhow in my opinion, especially if the concern if the locos are going to accidentally run. Its arguably the "safest" option given the "I don't want a throttle to accidently run stuff" requirement.

So even with DC operation disabled the headlights will illuminate? I never tried that, and I'm surprised.  Seems counter-intuitive. I thought "no DC" meant "no DC". or no motor, sound or lights.