I use 12 volt 3mm warm white LED's for most of my headlights and don't need the resistor as it is built into the LED. I get mine from LED-Switch company or All Electronics, both good sources for LED's. Just another option when doing LED installations for headlights. If your DCC decoder is set up for 3 volt lighting then you just need the regular LED, not the 12 volt one and no resistor. Hope this doesn't confuse you but I like to keep my wiring as simple as possible.
-Bob
http://www.led-switch.com/12%20volt%20LED.htm
Life is what happens while you are making other plans!
CNWman:
Don't be afraid to ask more questions.
Glad we could help.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Wow, this is the LED info. I've been looking for! So glad to have found it, guys. Thanks!
Your answers are not long winded. they were very helpful. I may not be young, but sometimes i need help. I not fond of reading thru books. so when im able to get info without a bunch of other stuff to filter thru always is a great help. thanks again.
Paul
Yodarian:
You are most welcome. I'm glad you were able to make it through my long winded answers.
I'm looking forward to practicing some of the things you have told me. i will be sure to let you know how things work out. I can't thank you Dave enough for all the help. I'm so thankful i found this forum.
Sincerly,
Hi Yodarian
Sorry, I forgot that you had mentioned the Bachmann DCC system. Brain fart.
It doesn't matter which way the resistor goes.
thank you for breaking that down for me...i will be looking up your suggestions. as for if im running DC or DCC...as stated in my first reply, I have installed EZ bachmann DCC decoders in all the loco's I wanted and am running with a basic Bachmann EZ command throttle. the one thing i didn't see in your reply was does it matter which way the resistor is installed.
Those are all legitimate questions. No need to apologise.
You can tell the positive side of an LED in a couple of ways.
If you are working with 3mm or 5mm round LEDs you will see that one lead is slightly longer than the other. The longer lead is positive. If you are looking at the small SMD 0603s there will be a symbol on the back, usually in green, that is shaped either like a triangle or a 'T'. The wide end of the triangle or the top of the T point towards the positive solder tab.
The other method is to simply test the LEDs. I have a power supply attached to my workbench that puts out 12 volts. It has red and black aligator clip leads, red being positive. If you are going to use 12 volts you MUST have a resistor in series with the LED (I'll explain 'series' lower down) or you will blow the LED instantly. Just hook up the LED and resistor and turn on the power. If the leads are connected with the proper polarity, i.e. positive to positive, negative to negative, the LED will light. If it doesn't light you won't have done any harm. Just reverse the leads and the LED should light up.
There are two basic ways that components can be connected - 'series' and 'parallel'.
'Series' means that the second component is connected to one lead of the first component so the power flows first through one component and then through the other. In the case of an LED and a resistor, one side of the resistor is attached to one of the LED leads and the other side of the resistor is attached to one side of the power supply. The other LED lead is attached directly to the other side of the power supply. Therefore, the electricity flows from the power supply through the resistor and then through the LED and then back to the power supply. It doesn't matter which lead the resistor is attached to.
'Parallel' means that two components are wired so the power goes to both components at the same time. For example, if you had two LEDs wired in parallel the positive sides of both LEDs would be connected to each other and to one side of the power supply, and the negative leads would be connected to each other and to the other side of the power supply. You would still need resistors so the way you would normally set it up would be to solder a resistor to each LED in series and then connect one side of the power supply to the other side of both resistors. The effect would be that each LED and its resistor are wired in series, but the two LED/resistor assemblies are wired in parallel.
I hope I haven't made this too complex. If you are confused, let me know and I can post some diagrams.
Also, somebody may be able to suggest a web site that explains basic electricity, or just google 'basic electricity' yourself.
One thing you have to figure out is how much power is being supplied to the existing light bulbs. You will need a multi meter to do that or you can consult the manufacturers' websites. Multi meters can be purchased for about $10, sometimes less. If your locomotive is using 12 volts to power the light bulbs all of the above applies. If it is using 1.5 volts then that isn't enough to light an LED and you will need a few extra bits to get the LEDs to work. That's a whole new subject.
Also, if you are running DC the LEDs may not light at very low throttle settings.
By all means, ask more questions if you need to.
Please tell us if you are running DC or DCC.
Thanks for the info, but sadly there are a few things I did not understand.
1. How do you know the positive side of an LED?
2. what side of the LED does the resistor get soldered to?
3. does it matter what side of the risisttor is soldered to the LED?
4. and lastly, what is meant by soldered in series?
sorry for sounding so dumb, but I'm just learning to work with electrical stuff.
I'm not sure what you know about LEDs already so be patient with me if some of this is too basic.
First, 'white' LEDs come in several versions of white ranging from 'ultra' white to 'warm' white. For your purposes I would suggest using warm white or 'sunny' white. The ultra white LEDs have a decidedly blue tint to them which doesn't look particularly like an incandescent bulb.
LEDs come in several sizes. The best size for your applications may vary a bit from locomotive to locomotive depending on the headlight configuration. Typical sizes are 5mm, 3mm, 1.8mm for the type of LEDs that come with built in solid leads, and '0603' or '0402' LEDs to which the wires have to be added directly (no leads unless you buy them with wires already soldered on). '0603' refers to the size i.e. .060" x .030". They are often referred to as 'SMD' LEDs (Surface Mount Device).
For your FT A unit you may find that a 3mm LED will fit very nicely where the existing headlight lens is now. I'm not familiar with the insides of the other units but you likely have some choices in terms of where the LEDs are going to be mounted. You can put them where the existing light bulbs are now, but often that doesn't give the best illumination. The advantage is that in most cases your number boards will still light up if the system is only using one bulb to light everything. If you have separate bulbs for the headlights and number boards then you should use separate LEDs obviously.
The other option in terms on locating the LEDs is to eliminate the light tubes and attach the LEDs directly to the back of the lenses. That often opens up a lot of space inside the shell if you are considering sound. I like to use 0603s for this because they take up so little space and they give out just as much light. If you have twin headlights and want to get the best lighting I suggest using two LEDs.
One trick I have learned is to apply power to the LED when you are gluing it into place so you can see exactly where the light is shining. They have to be centered in the lense. I use 90 second epoxy. Don't use CA because it may craze the lens.
As for wiring them, the most important thing is to make sure that the voltage applied is correct. For most installations the decoders put out 12 volts for lighting so you will need a resistor wired in series with one side of the LED. It doesn't matter which side but I try to always put the resistor on the positive lead just for consistency. LEDs are polarity sensitive but if you get the polarity reversed it's no big deal, it just won't light. A 1000 ohm resistor is most commonly used where the power supplied is 12 volts. You can go lower if you want the LED as bright as possible, or you can go higher if you want to dim the LED say for installation in an old timer steam engine. If you are not sure how much voltage the decoder supplies to the lights, either test it with a meter of check the manual on line. For most decoder wiring the positive lead is blue, the headlight lead is white and the reverse light lead is yellow. Also, check the manual to see if the decoder has a flashing light function. If so, the hook up will be no different than installing any other LED but you will use another coloured wire as the negative.
Soldering to the larger LEDs is a no brainer, although if you have clipped the leads really short you are safer using some sort of heat sink between the LED and the solder point. A pair of small needle nosed pliers with an elastic band on the handles to hold the jaws clamped shut works great.
Soldering to the 0603s is quite doable with a little practise. Expect to fry a few at first. Many people just use a piece of tape sticky side out to hold them. I prefer a set of spring loaded bent needle nosed pliers:
If you look carefully you can see an 0603 LED in the jaws. Looks daunting but like I say, once you have done some its relatively easy. You have to prepare everything properly. Apply soldering flux to the wires and the LED solder pads, tin the wires (30ga. or finer), tin the LED contact points, put them together and touch the soldering iron to the joint. Actually, if you have done the proper prep the solder flows instantly and you're done in less than a second. You will need a pencil tip iron with a constantly clean tip. I strongly recommend solder designed for electronics, not the stuff you installed your plumbing with.
You can buy the 0603s and 0402s prewired on eBay. I used to solder my own 0402s but I got lazy and now I buy them prewired on eBay.
There's tons more details but I've gone on long enough. Please ask if you have any questions.
thanks for the welcome. I have 4 Bachmann GP40's, 1 Athearn GP40, 1 Spectrumm by Bachmann SD45, 1 Bachmann FT A unit, 1 Bachmann Hogwarts Express, and 2 GE Dash 8-40CW. some came already with DCC, the others I installed Bachmann EZ command decoders into. I'm just running a basic Bachmann EZ command throttle. I have other Locos but they are dummies or i have decided to leave in DC configuration. If you are willing to help with some info...i would really love to learn how to wire a LED and possible make a flashing LED. any help would be awesome.
Hi Yodarian:
In case nobody has said it, WELCOME to the forums.
I'll second the suggestion to use LEDs instead of incandescent bulbs for all the reasons mentioned by MisterBeasley. If you tell us which specific locomotives you are working on we will probably be able to make some more detailed recommendations as to what size LEDs to use and how to mount them. Also, are you using DC or DCC control?
Bottom line is that bulbs will eventually burn out. LEDs will literally last for thousands of hours. Don't forget the resistors if your decoder doesn't have them built in!
I would recommend replacing your old bulbs with Light Emitting Diodes, LEDs. 3mm or 5mm ones work best, depending on the size of the openings in the engines. Get a 1000 ohm (1K) resistor for each LED. LEDs are polarized so if you're using DC you must get the polarity right. As long as you have a resistor in series with the LED, wiring them backwards won't hurt - they just won't light.
I personally like the "yellow white" or "warm white" LEDs to better model older locomotives. "Bright white" will work for modern engines.
If you are using DCC, you may (or may not) get by without the resistor, because some decoders have them built in.
LEDs have several advantages for headlights. They are cool, and won't melt your shell no matter how they are installed. They are bright and give a very direction beam, just like real headlights, so they cast a nice light down the track. They will also likely last forever, so the next time you need to remove the shell, it won't be to replace a headlight.
It takes an iron man to play with a toy iron horse.
Im new to all this and have aquired a few Loco's that have burnt out bulbs. Im good on the soldering, but not so good on figuring what size grain of wheat bulbs i should be looking for. What Voltage/Ma should I be looking for. I have mostly Bachmann with 1 Athearn. Any help ing the right direction would be greatly apreciated. THANKS