I'm Considering Changing my Bulb Signals to LED Signals

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I'm considering changing my incandescent-lit HO scale crossing signals to LED signals though I've been hesitant to do so. One reason, bad experiences with LEDs and another, for cosmetic purposes. But now I'm coming to the realization that using incandescent bulbs isn't helping, especially now that I'm trying to light up crossing gates in addition to crossbuck signals. If I'm not mistaken, I think trying to flash too many bulbs will not only use too much energy but also might fry your flasher units and I've burned out three of my flasher units (all from Circuitron) trying to flash crossbucks and gates with bulbs, one or two of them I repeatedly burned out, to Circuitron's annoyance. Plus according to what I've read and especially what I've been told, LEDs seem to be the better option, they're more energy efficient and they last longer (and work better as long as you wire and operate them right and always use resistors!)

I will show you which signals I'm talking about and what LEDs I am thinking of using for them.
Bachmann 42421 crossbucks
Sakai Seisakusho crossing signals (after their lights were replaced with 3.2mm grain of wheat bulbs)
Train Tronics (or TrainTronics) 510 crossing signals with their original bulbs
NJ International 1190 Boulevard/Over-The-Road (cantilever) signals. Left signal's lights replaced with 3.2mm bulbs, right signal retains original bulbs, which are smaller.

LEDs I was planning to use are 3mm LEDs, 1.8mm LEDs, and perhaps 4mm or 5mm LEDs, all red. I mean I wanted all of them to have 3mm LEDs but they might be too big or too long for my TranTronics signals and too small for my Sakai signals. So for the TrainTronics signals, I might use 1.8mm LEDs since the domes don't stick out too far, and I don't want my signals looking too silly! For the Sakai signals, being they have large brackets/housings/back-holes, I figure 4mm or 5mm LEDs might be better, they'll be less likely to move around, especially without the bulb holders these signals came with when they had their original lights. One of the signals still has its bulb holders but the others went missing! Because of that, 3mm bulbs and LEDs wouldn't be good for these signals and they can get loose and fall out of the signals too easily! But with the light holders, the light sources would have tighter spaces.

But 3mm LEDs should still be able to work with the Bachmann and NJI signals. I'll also need to buy the proper resistors for these. I prefer the blue resistors but may have to use beige resistors for different LED sizes.

I won't know until I acquire the LEDs and see if they fit. Thankfully LEDs don't cost that much, especially if you buy one individual LED.

And although it's settled I'm using SMD LEDs for professionally-made HO crossing gates, for my home-made crossing gates, which are wider and longer, I would prefer slightly larger LEDs. Would like it if I could use LEDs that looked like 7" gate lights. They won't be circle-shaped though like real gate lights. The 1.8mm LEDs are a good size, at least for 4" lights, but they have square bottoms instead of circle-shaped bottoms and I wish 1.8mm LEDs with round bottoms existed. 3mm LEDs have round bottoms but the domes are too long, in fact I think the whole LED that size is too wide and would over-hang the gate arm. I do not want to use 2mm LEDs, they look ugly to me and wouldn't be appropriate for my crossing equipment! I'll have to see what I can do, may even have to settle for 4" lights. Would also be nice if they made wider 1.8mm LEDs, LEDs that are just as flat as the 1.8mm LEDs but have wider and round bottoms, and perhaps wider domes, that or maybe flatter 3mm LEDs! I would prefer not to have square-shaped gate lights if at all possible, although they wouldn't be if I had the LEDs pointing up instead of outward. I'd do that with 3mm LEDs as well, I'd like them to point outward to get a more circular view but the LED dome as I kind of mentioned earlier, will overhang the gate arm, so probably best to have the LED point upward.

But I'm considering switching to LEDs and not just for efficiency but also to allow for more lights to be used now that I'm trying to light both crossbucks and crossing gates. I wanted to stick to incandescent bulbs for nostalgic purposes because bulbs were used on older real crossing signals up to the late 1990s, which was when LEDs started being used on real signals though some continued to be incandescent, plus incandescent lights fade as they flash, LEDs don't unless you have something that makes them do so. My NJI flasher module (now discontinued) is really good at making lights fade, even LEDs, but my Circuitron flashers will make LEDs turn on and off without fading, which is okay, I'll settle for that, but I would like it if I could make the LEDs fade in and fade out (I know Logic Rail has a flasher unit that makes LEDs fade as they flash, I think it's called Grade Crossing Pro, but I am wondering if there's anything I can add to flasher units from other brands to make LEDs turn on and off [more] slowly. See this thread asking that question https://modelrailroadforums.com/for...ny-way-to-make-leds-fade-as-they-flash.34233/) I also prefer to use transparent LEDs but still red both when they're shining and when they're off.
NJ International Flasher Unit.png
NJ International flasher unit (now out of production.) This can make LEDs fade while flashing, at least SMD LEDs.

I'm also thinking of using LEDs because I'm tired of burning out and frying my flasher units trying to flash multiple bulbs. Back then I was anti-LED but now I'm seeing using bulbs isn't such a good idea and now I understand why others won't use bulbs on their signals or anything else, be them model railroaders like myself or signal manufacturers, and others have been telling me something like "it's better to use LEDs," or "LEDs use less energy," or something like those. So now I'm thinking of riding the bandwagon when it comes to lighting! Plus I believe LEDs are less likely to fry the circuits on the flasher units!

Of course my other option is to just not light up my crossing gates at all, which I should go with, but gates without working lights on them is boring to me and they're harder to see in the dark, even with the crossbucks flashing. But I would like to be more energy efficient so that I won't have to keep replacing batteries as frequently!

So my new goal, at least this is what I'm considering, is to replace my bulbs with LEDs on my signals, using mainly 3mm LEDs, but also possibly 1.8mm LEDs and 4mm or 5mm LEDs. If anyone has advice on what LEDs to use, I'm open!

Thanks for reading.
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Well-Known Member
You can use whatever LED's that look right for the signal, 1.8mm round bottom LED's are available, but you'll have to look to find them, unless you have a specialist shop. I would stick with 1.8mm and 3mm as their easier to hide in the signal, 5mm would look out of place, remember to check for brightness, probably have to add a larger resistor to "dim" it down sufficiently or it's going to look like a Red Light District. :D
Thanks @Smudge617 . I was planning to order one LED each (one 1.8mm, one 3mm, one 4mm, and one 5mm) for trial, to see which ones worked and if any of them worked then I'd order more of them and not the ones that don't. When I say "work" I don't just mean their ability to light up or function but also their ability to fit.

I was trying to find round-bottom 1.8mm LEDs on Google but couldn't find any, then again maybe I didn't look long or hard enough. I've been referring to LED charts like this one


or maybe this one

I thought there were other charts, ones that labeled the LEDs by size like the second picture but more like the first picture that just shows the LEDs! But the 1.8, the smallest one shown, looks to only be square-shaped.

Perhaps you're right on the 5mm! Looking at it, that probably won't fit even into my Sakai signals! Maybe I better go with 4mm. It's just that with the holes so big in my Sakai signals, where the lights are inserted into, 3mm bulbs (which are currently in use) are thin and not confined, they wiggle around so-to-speak, especially without the aforementioned bulb-holder that you insert into the housings but insert the bulbs into. But if 5mm is too big, I better not!

And I believe you on the "Red Light District" thing! I've double-resistored my SMD 603 LEDs (added two resistors to a single LED) and they still shine brightly. I would use a 9.1-14V resistor and a 5.1-9V resistor together or a 9.1-14V and a 1-5V and the LEDs would still be be bright. Maybe time to triple-resistor them or use two 9.1-14V resistors! (I got my resistors from Amazon when getting my 603 LEDs and they came with 3 sets of resistors for each LED https://www.amazon.com/gp/product/B07P6L7P6V?ref=ppx_pt2_dt_b_prod_image&th=1.) I also found out how bright the even smaller NANO LEDs from MicroModz can be, they are bright as all get out and they come with resistors wired right in! https://modelmodz.com/Ultra-Nano-SMD-LED-with-pre-wired-resistor-p140972083 But they can be dimmed if you add them to the flasher unit that comes with the Busch 5934 crossing signals. By the way if you live in the US do not order from ModelModz, it took over a month for me to get my LEDs after I ordered from them! I'm looking for a place within the US that sells similar LEDs and will come faster! And it's expensive, I paid 11 US Dollars (forgot if it included shipping or was plus shipping) when I ordered from ModelModz.

But I'll look around some more for some round-bottom 1.8mm LEDs. Square ones I can use with signals, but round ones I would like to use on gate-arms just like the 4" and 7" lights. Although I want my gates to have 7" lights, I may just have to settle for 4" lights, which I think most railfans like better anyway! (For gate light information https://trains-and-locomotives.fandom.com/wiki/Crossing_Gate_Arm_Lights)


Well-Known Member
Try Amazon for your LED's, I find most of my electrical stuff there, fleaBay for the rest. As I don't live in the US, I use various suppliers, but save the good ones on my computer for next time, it's trial and error, someone will be along who can point you to good suppliers of stuff.
Your making work for yourself, triple resistors, that has to be a US thing, just try one, increase the size, try a 4K, check the ones you got factory fitted, so you know not to get any lower than those, if still too bright, go up from there till your happy, it's a trial and error thing really, you can get packs of various resistors for a few $'s, phone your local hobby shop, they might have or know where to get them, and you'll use most of them somewhere on your pike.
Somewhere on another thread, there's a pic of my pike all lit up, (I'm at work) think there's 40+ LED's/SMD's on there, and more to go, plus all the directional lights fitted to my loco's thats another 30+ all with resistors, so you will use them.


Active Member
You can get a resistor assortment pack from sites like Amazon, for incredibly cheap. All the values you would ever need. Remember different colour LEDs may need different resistor values for the same brightness. Once you know the values that match your LEDs you can order packs of those too, in a single value. I order in 100's quantities, only a few dollars.

D&J RailRoad

Professor of HO
Instead of the LEDs with the stiff leads on them, there are surface mount LEDs with very fine wire on em that can be routed down through the signal tubing.

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