Lights for a converted DCC loco

[John-NYBW]

I finally successfully installed a decoder in a my DC Atlas RS-1 and it is running fine with the shell off. I now need to install the headlights. I believe I've read in the past that I should replace the incandescent bulbs with LEDs although I've been unable to find any of the threads where this was discussed. Several weeks ago I purchased these from Amazon thinking they would suffice and would be easy to install:

https://www.amazon.com/gp/product/B06XPV4CSH/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

I hooked them up to the appropriate tabs on the decoder but they failed to light up. I then took one of the bulbs and touched the prongs directly to the rails and it gave a quick flash of light then went out and now won't light at all. I'm thinking maybe it got too much juice touching it to the rail. These lights are pretty cheap so there's no harm done but I need to know if I bought the wrong kind of lights or if I need to do something other than just hook the two prongs to the decoder tabs. Having finally gotten a decoder installed without frying it, I don't want to kill it now by making a mistake with the wrong bulb.

[Bayfield Transfer Railway]

LEDs run on about 2 to 3 volts, so yeah, that one died and went to LED heaven.

Get some 1000 ohm/1K ohm 1/4 watt resistors, which cost about 2 cents each, and put it in series with the LED.

Modern LEDs are quite bright, so you don't have to worry about getting the lowest resistance possible.  My LED headlights are too bright on 1000 ohms, and I use more like 2000.

But 1000 guarantees you'll be safe.

Also, LEDs have polarity.  Make sure the plus and minus are correctly connected.

 

[BigDaddy]

I can't tell from your link if these are daylight white or warm white.  Warm white is more prototypical for your model.

5mm is bigger than most of us use.  3mm work for me but some use surface mount, tiny LED's

There is a polarity to led's that must be observed, or they won't light at all.

Some decoders have resistors, some may require a specific trace on the circuit board be cut and some need resistors.  We can't see what you have.

You can also make your own LED tester with some scrap styrene and brass strip, wire and aligator clips

[hon30critter]

John-NYBW

I need to know if I bought the wrong kind of lights

Hi John-NYBW,

First, congratulations on your first decoder installation, and congrats on choosing to use an LED.

Micheal has addressed the need to use a resistor with most decoders so that doesn't need to be repeated, other than perhaps to say that it doesn't matter which lead the resistor goes on.

To answer your question about whether or not you got the right LED, that depends on the colour and the size. If you look at the eBay listing there are several options with regard to colour. The 'all white' option shows a 'cool' white LED which isn't particularly representative of an incandescent bulb, which most locomotives used. If you look at the selection that offers an assortment of colours, one of the LEDs is 'warm' white. That is a much better representation of an incandescent bulb.

If you got the cool white bulbs by mistake, keep them. They are great for mimicing florescent lighting. If you search eBay you should be able to find listings for warm white 3 mm LEDs for low prices.

The size that you ordered may or may not work for you depending on how much space there is to fit the LED in to. Yours are 5 mm. Most people use 3 mm LEDs and many are now using much tinier 0603 or 0402 versions that take up almost no space at all but are still very bright.

Here is a listing for pre-wired 0603 warm white LEDs. These even come with the resistors already installed:

https://www.amazon.com/uxcell-10pcs-Prewired-White-Emitting/dp/B07VXSPWCN/ref=sr_1_1?crid=AVH4Y39VAKCV&dchild=1&keywords=0603+led+warm+white&qid=1588816645&sprefix=0603+warm+white+led%2Caps%2C168&sr=8-1

The advantage to the 0603 LEDs is that you can do away with the light bars and mount them right behind the headlight lens so the light is phenominal. I use 90 second epoxy to hold them in place. I mount them with the LED illuminated so that I can see whether it is lined up with the lens properly, and they have to be held in place until the epoxy has set hard.

Otherwise, if you want to stay with round top LEDs that's just fine. Here are some warm white 3 mm LEDs:

https://www.amazon.com/100pcs-2pin-round-white-Lihgt/dp/B073QFHJ4B/ref=sr_1_148?crid=2Z88JER8Z61HM&dchild=1&keywords=3mm+led+warm+white&qid=1588817484&sprefix=3+mm+led+warm+white%2Caps%2C167&sr=8-148

Don't hesitate to ask more questions, or on the other hand, don't hesitate to tell me to stop giving long winded answers!

Dave

 

 

[tstage]

John,

Off-the-shelf white LEDs emit too harsh a white beam for an early diesel - like an RS-1.  What you want is a "warm" LED, which emits a slightly yellowish hue that mimics an incandescent bulb.

I like the 3mm Miniatronics "Yeloglo" LEDs.  The smaller, warm SMD (surface mount device) LEDs are nice too.  However, wires can be a challenge to solder to them - unless you have some good soldering experience.

Does your Atlas RS-1 use lightpipes to transfer the beam through the headlight lens?  Or, did the original incandescent bulb lay in a groove in the chassis?

Tom

[hon30critter]

tstage

The smaller, warm SMD (surface mount device) LEDs are nice too.  However, wires can be a challenge to solder to them - unless you have some good soldering experience.

My soldering skills with the 0603 LEDs used to be mediocre. I messed up the connections regularly and I wasted a lot of LEDs, and it seemed to take forever to get the wires attached. All that changed when I went from a Weller soldering station to an Xytronics one. A few days ago I soldered magnet wires to a half dozen RG 0605 LEDs with four wires each. It only took a few minutes and not one of the joints got fouled up.

Check them out:

http://www.xytronic-usa.com/shop/

Here is the current model of the station that I am using:

http://www.xytronic-usa.com/shop/item.aspx?itemid=253

I know that lots of people love their Weller stations. AFAIC, I wasted years struggling with mine.

Dave

[John-NYBW]

Bayfield Transfer Railway

Also, LEDs have polarity.  Make sure the plus and minus are correctly connected.

 

 

Did not know about polarity. Good to know.

[John-NYBW]

BigDaddy

I can't tell from your link if these are daylight white or warm white.  Warm white is more prototypical for your model.

This is a variety pack with lots of different colors, 10 to a pack. One of them is warm white. Another is just simply white. No daylight white.

[John-NYBW]

hon30critter

 

 

John-NYBW

I need to know if I bought the wrong kind of lights

 

 

Hi John-NYBW,

First, congratulations on your first decoder installation, and congrats on choosing to use an LED.

Micheal has addressed the need to use a resistor with most decoders so that doesn't need to be repeated, other than perhaps to say that it doesn't matter which lead the resistor goes on.

To answer your question about whether or not you got the right LED, that depends on the colour and the size. If you look at the eBay listing there are several options with regard to colour. The 'all white' option shows a 'cool' white LED which isn't particularly representative of an incandescent bulb, which most locomotives used. If you look at the selection that offers an assortment of colours, one of the LEDs is 'warm' white. That is a much better representation of an incandescent bulb.

If you got the cool white bulbs by mistake, keep them. They are great for mimicing florescent lighting. If you search eBay you should be able to find listings for warm white 3 mm LEDs for low prices.

The size that you ordered may or may not work for you depending on how much space there is to fit the LED in to. Yours are 5 mm. Most people use 3 mm LEDs and many are now using much tinier 0603 or 0402 versions that take up almost no space at all but are still very bright.

Here is a listing for pre-wired 0603 warm white LEDs. These even come with the resistors already installed:

https://www.amazon.com/uxcell-10pcs-Prewired-White-Emitting/dp/B07VXSPWCN/ref=sr_1_1?crid=AVH4Y39VAKCV&dchild=1&keywords=0603+led+warm+white&qid=1588816645&sprefix=0603+warm+white+led%2Caps%2C168&sr=8-1

The advantage to the 0603 LEDs is that you can do away with the light bars and mount them right behind the headlight lens so the light is phenominal. I use 90 second epoxy to hold them in place. I mount them with the LED illuminated so that I can see whether it is lined up with the lens properly, and they have to be held in place until the epoxy has set hard.

Otherwise, if you want to stay with round top LEDs that's just fine. Here are some warm white 3 mm LEDs:

https://www.amazon.com/100pcs-2pin-round-white-Lihgt/dp/B073QFHJ4B/ref=sr_1_148?crid=2Z88JER8Z61HM&dchild=1&keywords=3mm+led+warm+white&qid=1588817484&sprefix=3+mm+led+warm+white%2Caps%2C167&sr=8-148

Don't hesitate to ask more questions, or on the other hand, don't hesitate to tell me to stop giving long winded answers!

Dave

 

 

 

I have a handful of resistors left over from a previous project so I'm going to see if I can get these LEDs to work. If not I'll look into your suggestions. Thanks.

[hon30critter]

John-NYBW

I have a handful of resistors left over from a previous project so I'm going to see if I can get these LEDs to work. If not I'll look into your suggestions. Thanks

That's great John.

One small suggestion - don't use track power to test your LEDs even with the resistors attached. You will be pushing the limits of the LEDs. Henry showed an excellent set up for testing LEDs in an earlier post (without the resistors installed).

Dave

[richg1998]

This link is a little old.

http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm

I used a pot and got all the current readings for different resistors some years ago up to about 2.5 k but I have worked with LED's since 1972.

Rich

[markie97]

Bought the slightly yellow ones(forget the exact name) from the auction site. 3mm and also 1.8 mm with resistor already wired in. 20 for $10. Installed the 3mm ones in a couple of engines and very happy with the results. Direct replacements for the connections to the light bulbs only had to figure the polarity.

[rrinker]

 And as long as the resistor is there, trial and error is fine for figuring polarity, since if you hook the LED/resistor up backwards, it just won't light up. To reduce the number of 'errors', remember that the common on a decoder (blue wire for those with wires) is the + side of the circuit. For a regular 3mm type LED, this will be the side with the longer lead (before you clip them off to size) or, the lead closest to the rounded side (the other lead withh have a small flat in the base of the LED, this is the - side). 

 Here's a video showing 5 ways to figure out which lead is which on the LED:

https://www.youtube.com/watch?v=SRDgNR_yCms

 

 Resistors do not matter, they have no polarity. Plus they can go on either side of the LED, it makes no difference electrically. Good practice though is to make them all the same, always put the resistor in the positive side, or always put the resistor in the negative side. Just for consistency sake. The resistor itself can go either way as well - with the older stype markings, the color code started on one edge and didn't reach the other edge, so again it was good practice to line them all up the same way. Even though it doesn't matter electrically. Neatness counts, and engineers tend to be at least a little OCD about such things. 

                               --Randy