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Home :: Resources :: LEDFAQ

LED Light Frequently Asked Questions

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"Help me Decide... Pico, Nano, Chip, 5mm, 3mm, and 1.8mm Lights?”
What we are referring to when we mention size is the measurement across the width of the bulb.
If you are unsure of the size you need, you can try measuring the opening that you plan to fit the bulb into.
  • 3mm LEDs are a great size, suited to locomotive headlights, warning beacon lights, train running lights, ditch lights. Also for 1:18 and 1:43 Die Cast modifications and most RC uses, diorama street lighting, and many more projects! Brightness-wise there is not too much difference between the 3mm and 5mm LEDs
  • 1.8mm LEDs are small, used in 1:160 scale and 1:144 twelth scale models, and for 1:43 scale and 1:87 scale die cast vehicle modifications. These bulbs are great for models where there is not much space to fit a bulb. The 1.8mm are still extremely bright at 3,000mcd.
  • 5mm is a largest sized light we offer, we suggest using it for building lighting, passenger car lighting, or larger scale train running lights. If the bulb will not be seen, 5mm is a good choice since it throws the light around more than either the 3mm or 1.8mm We often use 5mm bulbs with our LED Fire Kit and our LED Welding Kit when they are staged inside of a building.
"Why Switch to LEDs?”
LEDs do not get hot like an incandescent, so you will not melt the roof of your building or the housing of your train, your diorama, water tower, or emergency vehicle!
  • LED’s last and last!! Over 10 years: 100,000 hours! You won't have to take apart your building model, diorama, Die cast vehicle, or train to change out the lighting. An incandescent bulb will last 750 hours or so. We guarantee our lights for two full years with free replacement.
  • LEDs give lots of light in a very small package. The LED’s we sell have a minimum of 5000 millicandels of light, approximately 1.45 Lumens. Some colors, like white, have 15,000 mcd. . Compare to a GE 14 volt Midget bulb which gives approximately .3 lumens
  • LED’s are tough and shock-resistant. There isn't a filament to break like those old incandescent. The light emitting diode is encased in solid epoxy which can even be sanded if desired.
"Do I need AC LEDs or DC LEDs?”
Universal LEDs
If you are
  • running your LEDs directly on your railroad track power,
  • hooking them to the DC accessory outlet on your train's power pack,
  • to your dolls' house transformer power supply...
  • or other existing power supply
  • Get the Universal AC LEDs, guaranteed to work.

DC Trains switch polarity (whenever you back up) and train transformers have "spikes" or "ripples" as well as surges and interruptions.
There is nothing wrong with this uneven power for most devices, but for LEDs this spells trouble. To protect the lights from this, we have added a full wave bridge rectifier and a smoothing capacitor along with the resistor. Even if you have a DC train, and you only run your train at 12 volts or less as with the N Scale Kato power supplies, we still recommend getting the universal LEDs.

Running your LEDs on a 9V Battery or Regulated 12V DC wall adapter... Get our DC LEDs , they have the correct resistor and connector wire, all set to go, guaranteed.
How do I wire the Universal LEDs parallel? Fed by how much power?
Wire lights in parallel. Gather 1 wire form each LED and bring to + then gather the remaining 1 wire from each LED bring to ground. That's all that is needed! Each LED draws 20 milliamps so 20mA x say 5 LEDs is still only 100 milliamps. The lights already have a resistor rated for 7-19 volt operation so no worries on voltage input. The accessory side or trains side of your transformer will work just fine.
"DC and Universal, what's the difference and advantage / disadvantage of each?"
Universal LEDs have more protection built in to compensate for AC / DCC which switches polarity

and protection from non-regulated DC power supplies which can look like this and often deliver more than the listed amount of power. So for example a listed 12V non-regulated adapter can put out as much as 17 volts of power due to the low draw of LEDs. The little section covered by shrink tube you see in the picture has a full wave bridge rectifier for reverse polarity protection and a filtering capacitor to remove voltage spikes/dips. Then a resistor is added just as in the DC bulbs. The Universal are built for unstable power supplies, and ensure that the power making it to the LED is "smooth" DC power.

If you use a high quality regulated 12V DC adapter you will not need any extra protection since you will have "smooth" regulated DC power that the LEDs require. The DC lights are less costly since the do not have the bridge rectifier and capacitor. DC lights will run just as long as Universal, provided they have the correct power supply.

If you use an existing train transformer for some or all of the lights, you will need to get the Universal LEDs.
”Can I get more light spread?”
The LED’s we sell are “wide angle” LED’s, most have an average of 35 degrees of light spread. If you find you need more light spread, you can sand off the rounded top of the LED without harming the diode. This will increase your light spread to 100 degrees or even more.
”Can I fit my LED into a tight space?”
Yes, LED’s can be bent at the stalk up to 90 degrees to perpendicular and still light! LEDs used in computer keyboard and cellphones are often bent in this way. If you need a really small light, try our new 1.8mm LEDs.
"I have a Decoder Board....?”
The boards are only made to take care of the locomotive it has been installed in. You can add LEDs in addition to the ones on your board, going directly to the track power and leave the board alone.
If you have a burned out light or want to go ahead and change to LEDs, call Tech Services of the manufacturer to get their advice how to proceed. Or, talk to a certified technician such as J&J Trains
”How much power do these lights draw?”
The LED's draw only 20 milliamps of power. Less than 1/3 of an incandescent at 65 milliamps power. You can connect quite a few LEDs to your power source without dropping your power to your model trains.
DC Flashing LEDs, using a single 9 volt battery, how many could I install in a Project like a Police Car?
You can put as many lights in as you need to get a great effect.

We have installed the lights in many types of police cars and firetrucks. They really so much more real when lit up, and the LEDs are super bright! For modern emergency vehicles, we like to use the DC fast flashers in the light bar and on the vehicle. Headlights sometimes look better with normal speed flashers or our wig-wag circuit.

For the older era police and fire vehicles we use a normal speed red flasher in the dome light and either solid or flashing headlights and tail lights. If you are putting your car near your model trains and connecting to track power, get our Universal Flashers

Our 1000ma 12V adapter can run 50+ lights nice and bright.

When we don't want a wall adapter, we use a 9V battery. According to Duracell, their alkaline 9 volt batteries are rated 580 milliamp hours.

In our tests with Duracell, we connected 3 flashers to a 9V. The lights looked nice and bright for 40 hours. We have Strap/Switch Combos that make it really easy. The strap has an end that snaps onto the 9V terminals on any 9V battery and long tail of red and black wire that can be connected to the lights.
”Can these work outdoors?”

These LED’s are the same ones you see around car license plates and in flashlights. The Light Emitting Diode in an LED is completely encased in tough epoxy. Our Garden LEDs also have a marine coating on the electronic parts for years of carefree use.
”Can I wire these to my track power?”
Yes, you can. Our Bridge Rectified Universal LEDs are specifically designed to run on any track power. These lights are "plug and play" pre-assembled. You need to do nothing more to these lights! The bridge rectifier means "constant on" lighting with DC, AC, or DCC track power. Refer to the diagram that came with your locomotive to check where to attach the leads for your particular loco. To light a passenger car, you will need to run the wire down to the track through the "truck". Check back soon for a short article on attaching an LED to power on your rolling stock. In general, the red wire goes to the positive the black wire goes to the negative.
”Why Do I need Pre-Assembled DC LEDs ?”
An LED bulb can only handle 2 - 3.5 volts of power, depending on the color of the LED. White can handle more voltage than red, for example. If you were to connect an LED bulb straight to a 12 Volt DC power source without a resistor, you would see a very brief bright flash as the LED burns out. We have soldered a color-specific resistor to the LED so that it will work with your 9 or 12 volt DC power source without harming the LED. Our 12 Volt DC LED's can run on anywhere from 6 to 14 Volts and are fully guaranteed to work, with a 2 year Replacement Guarantee, if you run the LED at the correct power.
”Why do I need Universal or AC LEDs ?”
An LED can only handle 2-3.5 volts of DC power. AC Trains, Digital Command Control Trains and DC trains have power supplies putting out 7-25 volts. We have added a full wave bridge rectifier and a larger ohm value resistor to these LEDs to protect the LED from both the higher forward voltage, and the switching polarity of AC and DCC trains. The great thing about the Bridge Rectifier is that these lights stay lit even when the trains are run in reverse!
”You say AC or DC, which is preferred?”
The LED’s are made to run on DC power. If you are running AC, DCC or plan to run DC in reverse (backing up) we recommend our 7-19 Volt Universal LEDs.
”How many LED's can I wire in parallel?”
The LED’s we sell draw 20 milliamps of power. So check your power source. If you have a wall plug power source with 1Amp of power you can run (1000 / 20) or 50 lights in parallel!
”Can I mix colors, sizes, flashing and solid in the same model?”
Yes! You can mix any color light and size of light (and solid and flashing) in the same application. see a great example of this:
”What Can I used LEDs in?”
You can use LEDs in Locomotives, passenger cars, buildings, emergency vehicles, model boats, model airplanes, model dioramas, RC Boats, Planes, Helicopters, Trucks. The durability, low heat and extremely long life of LEDs make them by far the best choice for every type of modeler! check out our gallery to see some great photos that our customers have sent us!
One thing about flashers especially that we should emphasize: They need to stay flashing! And the biggest thing is flashers that stop and go to steady after some period of time on power. We don't like to dwell on how much time it has taken to get the ones we carry now. Let's just say a lot of trial and error, and a lot of pitched lots of LEDs. We have test boards everywhere with LEDs connected to various power supplies. Some of them for years now. There are 2 things that go into making LEDs we can guarantee for at least 2 years of use 1)high quality chips 2) perfect soldering technique. We trained the factory we use now ourselves. And financed their purchase of some very high quality Taiwanese ESD irons, sooner than have them use the irons they already had available. Using other LEDs is kind of hit or miss. It's worth it we feel, to pay a little extra for LEDs that don't need to be removed down the road when they fail.

Still have questions we did not answer? Contact us! Or call 303.410.1118 We will be happy to answer your questions!

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