Friends:
I am brand new to this forum. I was advised that there is a wealth of expertise on this forum, so I am hoping you all can help me out. I am Looking for some advice on powering lights on a G scale Spectrum 2-6-0 Mogul #81498 (DCC ready). This is my first crack at converting a Bachmann Spectrum 2-6-0 locomotive to battery power and wireless DCC control, so I feel like I am flying blind. But I am learning a lot in the process and making progress. I am adding an Airwire G3 DCC board w/wireless control, Phoenix P8 sound and 14.8v Li-ion battery power supply to the locomotive. I am installing the Airwire and Phoenix boards, speaker and the battery all in the tender (yes it all fits). The loco and tender have two connections between them. A two pin to the chuff trigger which has been connected to the P8 board. The four pin connector I plan to use to run power to the lights on the locomotive and the smoke generator (one pair for the lights and one pair for the smoke generator). Finally I am adding a third two wire connection from the Airwire board direct to the motor on the locomotive. I have also disabled/removed all track power pickups on the loco and tender, so only the battery can provide power.

My first question is this: It appears there is a resistor in the lead to the headlight, but I cannot find any resistor in line to the LED’s that light the ashpan and firebox. With the 14.8 V battery being used (which actually runs at 16.2 V), will I need to add a resistor in the line from the battery to the ashpan/firebox LED’s, and what size resistor should I use. But I need to know if I need to protect the LED’s in the ashpan/firebox with a resistor using the 14.8 v battery. The headlight and ash pan/firebox LED’s all are on the same circuit from the loco’s main internal board.

Also, I have a follow up question for you all. Does the wattage of the resistor matter (i.e. quarter watt, half watt, 1 watt, etc.)? On the Bachmann forum a subscriber recommended I use a 480 ohm resistor. I was experimenting with a 1K ohm resistor (1 watt) last night, and when I put it in series with the headlight and firebox/ashpan LED’s, the headlight barely lit while the firebox/ashpan LED’s seemed to work okay with flicker. As I previously noted, there is a small resistor under shrink wrap in one of the leads to the headlight, so it makes sense the 1K ohm resistor I added dropped the voltage too low for the headlight. I did not see any resistor on the little LED board for the ash pan light LED’s. I could access it when I removed the motor cover under the chassis to access the motor. I cannot get to the firebox LED’s without disassembling the boiler from the chassis (which I am trying to avoid at this point). The schematic in the Bachmann loco manual does show the resistor in line with the headlight only, but does not show a resistor in line with the firebox/ashpan LED’s. But all lights will be powered from the same G3 decoder terminal, so I just have to determine the right resistor value to place in the line so all lights work correctly.

As noted above, I am placing the Airwire G3 decoder in the tender (rather than in the locomotive boiler) with the battery and Phoenix sound card. So I wanted to use the existing four wire plug between the loco and tender to bring power from the G3 board terminals for the smoke generator and one of the separate light driver terminals. I was going to power the lights direct from the battery, but decided to go through the G3 board after all, so I can turn the lights off when running in broad daylight (to reduce battery draw) when the lighting effects would be minimal anyway.

I have pulled the main board with the smoke generator attached to it, out the front of the smokebox. Bachmann kindly put in enough lead length that I can pull it all the way out and access it). I have traced the leads from the four wire plug at the rear of the locomotive to the locos internal main board and figured out which two pins send power to all the lights (headlight, firebox/ashpan LED’s), and which two pins send power to the loco’s internal board circuit for the smoke generator. So I believe I will be able to use the four pin connector between the loco and tender to supply power to both lights and smoke gen. separately from the appropriate decoder terminals on the G3 board. I have added a third two wire lead w/connector between the tender and loco to bring the battery power through the Airwire G3 card motor driver terminals direct to the motor. I actually removed the track power leads from the locomotive driver frames motor, and disconnected the tender track power pickups so that all locomotive functions are powered only by the Li-ion battery. The motor seems to be working perfectly wired direct to the G3 motor terminals. I can use the Airwire throttle to control the motor speed and direction.

So I am down to just figuring out what will be the best resistor values to use in the power leads from the battery through the G3 board, to the lights and also the smoke generator. The 14.8 V Li-ion battery is actually putting out 16.2 V. I think I have the smoke gen figured out as noted below. So I just need to get the light circuit fine tuned with the right resistor in line so I don’t burn out the lighting LED’s but send through enough voltage so they all work correctly.

For the smoke generator, the Bachmann manual that came with the locomotive recommends not to exceed 16 V input to the smoke generator circuit. So of course my battery is running at 16.2 V. With the 1K ohm resistor (measured 975 ohms) added in line to the smoke gen, it wont make smoke and has less than 1 V (.88 V) measured at the generator. With a 1 ohm resistor added in line it makes smokes like crazy with a reading of 11.8 V at the smoke generator, so I think that will work. I experimented with hooking up a track power MRC Tech II power pack rated at 10.6 V output to the smoke generator, and it produced “moderate” smoke at wide open throttle max output. So the 1 volt increase from 10.6 to 11.8 V greatly enhances the smoke produced, and is well below the Bachmann recommended safe max voltage of 16 V.

So that is where I am at. Thanks again for any help you all can provide on this electrical puzzle and any other advice you can share on this overall conversion to battery power and wireless control.

Best to all,

Mark

Mark,

A couple of thoughts.

Li-Ion batteries may have 16.2 volts when fully charged, but not for long. It will drop to 15 volt fairly quickly.

I dropped the output voltage with a 10A diode as my ESC doesn’t like 16.2V.
https://www.aliexpress.com/item/10A10-6A10-rectifier-diodes-6A-1000V-25pcs-lot/32832151957.html?spm=a2g0s.9042311.0.0.27424c4dNp12oo
which drops about 0.5V and you can add many in series if you need to drop more (I used 4 and got ~15V.) However, if your smoke unit works on 11.8, then go for it.

A 1K resistor obviously works for you for the ashpan, so why not use it? I haven’t found it critical that the LED should be at maximum brightness.

There is Ohms law that tells you how to calculate the resistor for a LED…

Or you can read about LEDs and figure it out.

Or you can use an LED calculator program.

I get this question all the time, and I have a page explaining things and with a link to LED calculators

https://elmassian.com/index.php/large-scale-train-main-page/dcc-battery-rc-electronics/misc-electronics/led-lighting-basics

Greg

Welcome Mark

Welcome, Mark.

If you are running outside, there’s a very good chance you will never even notice any lights except the headlight. Heck I never even knew my ashpan was lit as I was always running outside. Inside is a different story, but I’m not sure how it ends. (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-foot-in-mouth.gif)

Batteries and smoke typically don’t go together as smoke generators seem to consume lots of power.

OK, not any help, but it may be time to decide on what you really need? (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-embarassed.gif)

Welcome aboard, Mark.

Gentlemen:

Thanks for the welcomes to the forum. I hope to contribute as well as learn a lot on here. I am new to large scale model railroading and outdoor garden railroading. I am excited to have the time to do this having retired in 2018. I feel like I have been going back to school learning about wireless control and battery power conversions, etc.

Bruce:

Good points about the lights and smoke. I am setting up a large outside layout and hope to sit in the gazebo at dusk and run trains when it’s cool. I would hope the ashpan lights and headlight would be visible at these times. The smoke is more about just being able to do it. Probably won’t use it that much as if there would be any breeze on a given day, the smoke would be instantly blown away anyway. But who knows, I might run indoors occasionally as well. Maybe my wife will let me run a spur line through a window or a dedicated hole in the wall. LOL

Greg:

I’m sure you do get a lot of questions on this forum from newbies, but isn’t that what these forums are for, to help us learn from each other? Please give this newbie a break. As I noted, I’m just getting into large scale outdoor model railroading to keep me from playing with my toes, and it has been years since I did any significant electronics hobby work. Yes, I know Ohms law, but have had almost nil experience with applying it to LED’s and calculating voltage drops. I actually did come across your web site before I got signed up and approved on this forum and read some of the material you have there. It was very helpful and a great resource. Thank you for making that available to model railroading hobbyists. I have your site bookmarked for future reference. I did try some calculations that I think are correct, but I was still looking for some affirmation that I was on the right track (pun intended) with what I came up with. Was just hoping to draw on someone else’s prior experience.

All that being said, I am very excited about getting seriously into this hobby. I was a model railroader (HO scale) back in the late 80’s/early 90’s, and I still have all that equipment, but my how times have changed. I have a lot to learn to be able to utilize the advancements in technology that now exist in model railroading. And I look forward to learning from all of you.

Best regards,

Mark

Mark

The locomotive you are asking about is the first release of the Spectrum 2-6-0 which is quite old. The newer release has totally different wiring and has a much better drive. Even on this older locomotive, most of the electronics for controlling the light features is on a single board.

Looking at the Bachmann parts site they list the same board for the 4-4-0, 2-6-0 and the outside frame 2-8-0.

(https://estore.bachmanntrains.com/index.php?main_page=popup_image&pID=5028)https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_145&products_id=5028

This board has the current and voltage regulation on it. I believe it also has the firebox flickr circuits on it so if you are removing it you will need either current regulation or the simpler resistor between your power source and the lighting.

Hope that helps.

Stan

Bruce;

Just visited your web site and looked at your beautiful outdoor JBRR. Well done!

Mark

Mark,

Since you’re in Illinois, you might want to consider a trip to Nashville, IL for a session during one of Andy”s BS Ops weekends. Even if you’re not into operations, it’s a great time to ask questions and see how things can be done.

Stan:

Thanks for your thoughts. This 2-6-0 locomotive has had an upgraded drive gear installed. I also have a 4-4-0 of that same era I purchased that I had to put a new NWSL gear in as well. Both locomotives are in excellent condition otherwise. But time will tell on reliability. Apparently, the drive gear is the weak link in Bachmann steam locomotives. I am actually leaving the internal board in the locomotive and running the battery power through the Airwire G3 board to the appropriate connections on the Bachmann board for the lights and smoke. Conversely, I direct-wired the locomotive can motor to the motor terminals on the G3 board and removed all track power pickups from the loco and tender. I have totally committed to the Li-ion battery power source, so hope it doesn’t let me down. I want to stay dead rail, so i don;t have to worry about removing tarnish and oxidation from the rails every time I want to run. Okay, there will still be the issue of sticks, leaves and deer poop! Maybe I can mount a blower on a flat car to push ahead of the locomotive! Hmmm… LOL

Mark

Great idea Bruce. My wife and I do like Nashville and this would be a great excuse to go again! Thanks for the lead.

Mark

Mark said:

Great idea Bruce. My wife and I do like Nashville and this would be a great excuse to go again! Thanks for the lead.

Mark

You mean there’s something else to do in Nashville besides visit Andy and Jane??? (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

Bruce D. Chandler said:

Mark said:

Great idea Bruce. My wife and I do like Nashville and this would be a great excuse to go again! Thanks for the lead.

Mark

You mean there’s something else to do in Nashville besides visit Andy and Jane??? (https://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)

Well, yea. A good breakfast at the Little Nashville Diner.

Okay, there will still be the issue of sticks, leaves and deer poop! Maybe I can mount a blower on a flat car to push ahead of the locomotive!

There’s a guy somewhere makes a motorized counter-rotating brush or sandpaper mounted on an old tender for clearing the track.

Try Reindeer Pass.

Doc

Gonna have to get me one of those track clearing cars!

Here is a short video with mine in action…

Mark said:

Stan:

Thanks for your thoughts. This 2-6-0 locomotive has had an upgraded drive gear installed. I also have a 4-4-0 of that same era I purchased that I had to put a new NWSL gear in as well. Both locomotives are in excellent condition otherwise. But time will tell on reliability. Apparently, the drive gear is the weak link in Bachmann steam locomotives. I am actually leaving the internal board in the locomotive and running the battery power through the Airwire G3 board to the appropriate connections on the Bachmann board for the lights and smoke. Conversely, I direct-wired the locomotive can motor to the motor terminals on the G3 board and removed all track power pickups from the loco and tender. I have totally committed to the Li-ion battery power source, so hope it doesn’t let me down. I want to stay dead rail, so i don;t have to worry about removing tarnish and oxidation from the rails every time I want to run. Okay, there will still be the issue of sticks, leaves and deer poop! Maybe I can mount a blower on a flat car to push ahead of the locomotive! Hmmm… LOL

Mark

Mark

If you have kept the board in the locomotive that control the lights and this board is indeed the same as the 2-8-0s, then no additional resisters are needed. You can follow the instructions for converting the board from DC wiring to DCC wiring.

Using the following link scroll down to the bottom which shows the wiring for the board using both DC and DCC.

https://www.bachmanntrains.com/home-usa/dwg/dwgs/81294.pdf

Stan

Stan - yes I am keeping the Internal Bachmann board in the locomotive and feeding the power from the battery through the Airwire decoder to the Bschmann board to the lights and smoke Gen. Thanks for the input. That sounds great!

Mark