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They may be small, but they're easy to work with

 

Our 2x3 LEDs are surprisingly easy to work with. Having flat surfaces, they're simple to hold for soldering, gluing, painting, etc. The gold plated solder pads make connecting wires a snap and the ceramic case is quite durable.

 

How's the LED going to be used?

 

The type of wire you connect depends on your application. If you plan to install them as smaller (and brighter) replacements for lights currently in your locomotives, and you expect the locomotive shells may be removed regularly for mechanism cleaning, etc., you may want to consider using a multi-stranded wire (about #30 or so) for flexibility in case you need to move things around a bit.

If your application is as a light source in a structure, a solid conductor wire like Radio Shack's #278-501 (red), or #278-502 (white) 30 AWG Insulated Wrapping Wire is a great choice. It's inexpensive at about $3.00 and comes on a handy 50 ft. spool.

If your plan is to make flood lights or some type of lighting that will use tubing (like our .018" tubing) for conduit, you'll definitely want to use insulated magnet wire. Or, if in your plans you want to hide the wires totally from view (in cracks or grooves in structures), magnet wire's the choice. Four of our N5038 #38 insulated magnet wires will fit through a hole made with a #80 drill. This stuff's easy to hide.

Whatever the choice, one rule to remember: Always pre-tin the wire and make sure that your solder has a flux core or that you're using a small amount of liquid flux. This ensures that the amount of time required for your soldering tip to be on the LED's solder pad to make a good joint is going to be the absolute minimum. The two easiest ways to kill an LED are: excess heat from soldering and excess voltage (or current). With good soldering  practices and protection from excessive current, these LEDs will easily last 50 times as long as an incandescent bulb, give off much more light and virtually no heat. What a deal! 

 

Prerequisites:

Regardless of the type of wire you're going to use there are several things that will aid in your success in working with these LEDs.

  1. Good optical magnification (Optivisor, etc.)

  2. Bright lighting that's position adjustable.

  3. Comfortable work area with your holding fixtures elevated so you can sit upright with your arms relaxed while soldering (helps prevent the shakes and fatigue).

  4. Good magnification (really important)

  5. Small, low wattage (we recommend our 12 watt) soldering iron with needle tip or small chisel tip. Alternately, a temperature controlled soldering station (much more expensive but hard to beat).

  6. Low-temperature wire solder with a rosin flux (not acid flux) core. Our N4200 (Kester, 2% silver solder in the handy dispenser) is an excellent choice. Alternately, Kester 63/37 or most  silver-bearing low temperature solders will work.

  7. To aid the speedy and smooth flow of solder and thereby minimize the heat the LED is subjected to, you will find that a small amount of liquid flux, applied with a tiny brush (or toothpick) applicator will be very helpful. Select a flux that is easy to clean. GC Electronics' #10-200 is an excellent choice.  Only a tiny amount is required.

  8. Simple test fixture (9 volt battery, an appropriate resistor, and clip leads) to test every wired LED prior to installation. All of our LEDs are pre-tested but you'll want to make sure you didn't zap one during soldering. It's better to know this prior to installation than after. Our N8021 LED tester works great for this.

  9. Good magnification (yes, I know...)

Wiring LEDs

We'll focus on wiring our LEDs using magnet wire. We feel that once you've got this technique down, it can be applied, in general, to the other types of wire we mentioned earlier.

  1. Pre-cut your wire longer than you think you'll be needing and tin/strip both ends of each wire. Even if you plan on putting this wire inside our .018" tubing and will probably have to snip off that tinned end. The reasoning here is that while you're setup to tin/strip, you'll probably be doing more than one wire and it's easy to do both ends at that time. This will facilitate easy testing of your wired LEDs. Test every one. The actual tinning/stripping procedure for our magnet wire is covered in detail in the Wiring Tips section of the Magnet Wire listed under Lighting Products. If you need to review it, click here.

  2. Holding of the 2x3 LEDs for soldering can be accomplished several ways. If you think you're going to do a lot of them, you might want to make a simple fixture using something like our N4400 Micro-clip w/Smooth Jaws, or Radio Shack's #270-373. These are handy little copper plated spring clips that can be soldered to larger holding wires or screwed down for mounting. We highly recommend that you cover the smooth jaws with either electrical tape or shrink tubing to provide a non-scratching cushioned surface if you're using the clip to hold wire (such as our N5038 #38 Magnet Wire). We made our first fixture out of a clothes pin sanded flat on the end with a steel pin through the 2 wooden clips to prevent side-to-side wobble. Double-sided tape on a metal or plastic block will also work. Whatever you decide, it is highly recommended that your fixture also have the ability to hold the wire-to-be-soldered in position. Two spring clips, extra tape, whatever. The important thing (and a huge confidence builder) is to have both hands free to make your solder connection. One to hold the solder, or pointed toothpick to adjust wire position, or brush to dab flux, and the other for control of your iron. The key is to make it easy and it'll work every time.

  1. Pick a pattern and stick with it. That is, get in the habit of soldering the cathode side first or the anode side first. We recommend using red wire for the anode (+) side. This follows normal electrical convention (the plus lead on your car battery or train power supply, for instance). The green wire for the cathode (-) side. If you're doing several, do all of one color first. We like to solder all of the cathode connections first because the LED face is marked with a small line denoting the cathode connection. Once this is done, there's no possibility for confusion (and shorting LEDs).

 

 

  1. To solder the first wire, lay it down on the solder pad so that the point where the tinned portion of the wire stops  and the insulation starts in lined-up with the back edge of the solder pad. Let the remainder of the tinned portion hang off the front toward you. Or, you can either pre-cut the wire so that the tinned portion is no wider than the solder pad. It's up to you. Follow the soldering procedure we covered in detail in the Wiring Tips section of the Magnet Wire, making sure to minimize the time your iron spends on the solder pad of the LED. If you've left the tinned part long, snip it flush with the edge of the LED. Carefully slicing it off with a sharp scalpel also works well. Don't nick the gold pad.

  2. Gently  bend the wire slightly to the side so it's not hanging over the other solder pad. How you position the second wire depends on how you're going to use the LED. If you're making an HO ditch light for example, you'll want both wires exiting the LED from the same side. In this case, you'll want to trim the second wire so that the tinned portion is only the width of the solder pad and position it so that insulation starts as the wire exits the pad. If this LED will be mounted as a floodlight, you'll probably want the wires to exit up away from the LED back and be twisted together. In this case, turn the LED around and solder the second wire so that it exits the LED in the opposite direction from the first wire.

  3. If you've used additional flux, gently clean the back and sides of the LED.

 

Testing your work

Whether you're planning on wiring a bunch of LEDs or just one, we cannot overemphasize the importance of testing your work before placing wired LEDs in you structures or other projects.

Imagine building for example, a streetlight and discovering after the detailed assembly that somehow, the LED got fried or is shorted. At a minimum, strong words would likely ensue...

We use to recommend building a small portable tester and even included a circuit diagram and parts list on this page. Well, no more. We now carry an Intelligent LED Tester that is very inexpensive and will automatically test any 20ma LED regardless of color or pin configuration. It has a built-in state-of-the-art current source to ensure each LED receives 20ma (± 1%) current. Simply snap it onto a standard 9-volt battery and you're ready to go.

 It's extremely portable so it can be used to see how different lights look at various places on a layout, or in and around different structures.

Happy testing and may all of your wired LEDs work the first time. Please let us know if you have any questions or problems.

 

Copyright © 2002, 2006 Ngineering

Last modified: March 18, 2007