YES!

Looks Great!

Did you order the pre-wired SMDs?  I couldn't imagine attempting to solder that miniscule magnetic wire to that near-invisible soldering pad...  My entire fleet is going to have functional ditchlights so this is a wonderful post!

Prewired for my convenience

Johnny,

Absolutely I ordered prewired SMDs. Even so the magnetic wire snapped once or twice, forcing me to get out the magnifying lens.

My advice... order some spares!

James

Oh Joy...

Can't wait to snap my first wire... ha!

I first started looking into the SMDs for truck illumination (not sure what railroaders call these lights) but, as I look into it, I think using body-mounted fiber-optics might be an easier solution and would eliminate the probability of breaking one of the 4 sets of magnetic wire every time I'd need to take off the shell.

My goal is to have step/walkway lights, truck lights and number boards all illuminated and mapped to be on constantly like the prototype in my area. Personally, I appreciate accurate lighting details more so than any other superdetailing aspects.  It just completes the entire feel of a true model for me.

SMD LED lovers should model Blackpool trams

Some UK modelers actually have built many of the "parade" trams in "00" scale, lights an' all.

Take any in-progress photos?

I've been mentally playing with the idea of adding ditch lights to my locomotives, and I'd like to see how you routed the wires...

Wiring Simplicity

Jeff,

No progress photos, which means I missed out on the opportunity for an MRH article. Next time...

However there's not much to it.

The locomotive uses 8 Warm White SMD LEDs, 4 for the ditch lights and 4 for the headlights. Each came prewired with magnetic wire along with a 1K Ohm resistor from Streamlined Backdrop Services. I wired up two LEDs each to the front and rear headlight functions on my Tsunami decoder. The ditch lights were wired to the F5 and F6 functions on the board. I wired both the fronts to F5 and the rears to F6 to give me control of the ditch lights independent of the headlights. Because of this I cannot have the ditch lights flash for grade crossings, however independent control was a higher priority.

The ditch lights are pilot mounted so I simply drilled into the shell and fished the LED through. A ditch light casting covers up the hole. Otherwise the LED simply sits in the middle of the casting.

Since the wire is so small I was able to attach it to the shell in some key locations with a little CA. However most of the wire is loose in the shell to allow for easy removal. If you look close at the front window on the engineer's side of the cab you can see a bit of the wire.

The direct link to the product I used is  http://store.sbs4dcc.com/sbs4dcc0603smdwarmwhiteledpre-wired38gamagnetwire.aspx. I'm not affiliated with SBS, just a happy customer.

rather wire my SMDs

I rather wire my SMDs because I buy them at $.18 US each. I am just finishing adding front and rear ditch lights, front head lights, rear lights and adding QSI Titan sound. Which I had to mill out a 1.1" x 1/4" deep recessed in the fuel tank for one of the speakers. To a pair of Kato SD70MACs Conrail for a fellow Amherst Railway Society club member. All lights are SMD 603 and 403.

Joe

Your choice

Rotary beacons

Decoder Function

SMD LEDs, pre wired or roll your own

I'm kinda' curious how many folks buy their LEDs pre wired and how many solder those tiny lil' wires on themselves.

Personally I'm to cheap to buy the pre wired ones, especially when you can buy them, out of China, in the hundreds for a few cents each. My first attempts at soldering wires to these tiny buggers did not go well but as time progressed I figured it out. You need a good magnifying lamp and about 1 2/3 beers under your belt and it all works well... mostly.

I work in O scale so I don't usually need the really small ones, some of those "nano" LEDs are literally smaller that an O scale light bulb. I normally use the 0803 size. small enough to fit but big enough to solder a couple of wires onto.

At any rate, the availability of affordable, tiny SMD LEDs has revolutionized the modeling industry.

SMD's Roll my own!

I make my own SMD light assemblies.  I model N scale, so using the 0402's is almost mandatory (though 0603's are OK for some applications).  I use 38 gauge magnet wire for mine.  The main reason for rolling my own?  I'M CHEAP, LOL!  I get the 0402 SMD chips at a cost of 20 cents apiece, and the magnet wire cost $6.00 for 2000'.  With N scale, that should literally last me a lifetime.  They're not too hard to wire up, I built a fixture to assist holding the chip and the wire in place while I solder it on.  It took a few tries to get the technique down, but now it's easy.  I use 'em for ditch lights, rotary beacons, number boards, headlights, step lights, as well as in structures.  An 0402 can be used in a small gooseneck porch light, a street lamp.....anything.  The magnet wires are so thin, they can be cleverly disguised and hidden.  IMO, buying them pre-wired is fine, if you care to spend 20x what they actually cost to make.  Me.....I'll pocket the savings and spend it on more stuff for the layout!

Questions

for the guys that roll your own. 

I'd be interested in a source. I know, google is your friend, but still it would be a help.

Second. I've worked with such small wire when led's first came out. How do you guys remove the varnish that insulates the wire? Scrape? Used fine sand paper? Or use some kind of solvent?

Bernd

Removing varnish

Bernd

If you have a freshly cut end of a magnet wire, the easiest way to remove the varnish is to use a soldering iron.

Just load the tip of the soldering iron with a small ball of solder. Pass the end of the magnet wire through the heated ball of solder a few times.

The solder will burn off the varnish and tint the magnet wire for you.

Bill B.

Varnish removal

Missed that point about using heat to remove varnish. Good tip. I always used a piece of 400 or 600 grit sand paper to remove the varnish. Never thought of using the heat of the iron.

Again, excellent tip and thanks much.

Bernd

Time vs Money

I did the same for removing the varnish, just passing it through a ball of molten solder works great.

And I'm well aware that it's much cheaper to build instead of buy. I chose to save time instead of money since this was a small project and the additional cost wasn't an issue.

James

fixture for soldering 403 smds

could you post a larger picture of your soldering jig for the smaller 402 smd LEDs. I am working in N scale as well.

cheers

Ben

Soldering fixture and sourcing SMD LED's

As requested, here is a larger picture of the soldering rig.  I got the basic idea off of Ngineering's excellent website.  http://www.ngineering.com/micro_wiring.htm#LEDtool

I made mine with a scrap piece of .032" aluminum, to which I glued a couple of component clips (get at any RadioShack).  I used good old contact cement to glue them to the aluminum.  As far as the LED's go, I get mine from Kingbright.  They are very "modeler friendly".  Here are links....

For 0402 (the REEEEELY tiny ones)

http://www.kingbrightusa.com/category.asp?catalog%5Fname=LED&category%5Fname=KCChip+SMD%2D1%2E0X0%2E5mm+%280402%29&Page=1

For 0603 (just tiny)

http://www.kingbrightusa.com/category.asp?catalog%5Fname=LED&category%5Fname=KC0603+LED+Height%2D0%2E25mm&Page=1

There are many more sizes.  For N scale the 0402 and 0603's are most common, but even 0805's have many useful applications.  

Here is the "big" version of my SMD soldering fixture

And a closeup of a completed LED

 Happy Soldering!

Carl

Varnish Removal

Another very effective way I've found to remove the varnish off magnet wire is to QUICKLY (and I DO mean QUICKLY) run the end of the wire thru a flame from a lighter or candle.  You absolutely CANNOT dwell in the flame, just pass the end of the wire thru it.  The varnish will burn right off.  I use this technique when putting the end in a blob of molten solder doesn't get the varnish completely off.  For some reason, the varnish is thicker or just more tenacious in some spots, for some reason.  The flame trick works well for these instances.  You don't have nearly as good control, but it really doesn't matter.  You just snip the end close to where the varnish is still on the wire so just a tiny (1/32" or so) bit of the wire is bare.  You will know if you dwelled in the flame too long....the wire will simply vaporize!

Carl

Thanks

Carl for the larger picture and the links. Off to save the links in my favorites.

Bernd

What brand and where to get the solder flux

What brand of solder flux is appropriate and where can we get it? I know Laurie McLean (of various yahoo Soundtraxx and narrow gauge groups) has mentioned Carr's liquid flux. Where can we buy this and what other brands might be suitable for soldering to the SMD tiny LED's? Laurie and others have stated that the rosin core electronic solders are not adequate for quick and light touch soldering the SMD components require and that a proper electronic flux which can be applied with a brush or similar is the best way to get reliable solder joints.

John

We have SMD type solder paste with flux in tiny syringes.

We happen to use the same SMD industry stuff for assembling our frogs. It's lead free and the smallest metal grain size for SMD we can get. You shouldn't need separate flux for SMD if you heat the parts properly.

Here's a picture of the fine grain of the paste when applied to HO, N and Z frog surfaces. You can similarly just paint the edges of the SMD parts to make sure you don't put too much solder on.

http://www.proto87.com/all-frog-assembly-fixture.html

See our frog tool page for as above ordering.  We also have stainless fine needles for the syringes. (0.010" and 0.020" ID) that we normally use for gluing track details.

the right wire

Make sure you buy the solderable polyurethane coated wire, some other types don't melt with a soldering iron.

I hold my LEDs in a small heatsink clip which is narrow enough to allow access to the solder tabs, stops the LED from getting too hot and holds it one place! Tin the wire first, I make that bit too long. I then place the wire along the solder tab on the LED and heat it for a few seconds to make the join. Once soldered I cut off the over hanging bit of tinned wire.

To avoid disappointment I also check the LED with a LED tester (so no resistor is needed) at each stage of wiring and installing to check it is working. It is really annoying to install one to find that you broke a wire or shorted it out when fitting.

I connect each pair of headlight LEDS or ditchlights (if they don't need to flash) in series, thus saving running all the wires back to the decoder and using less resistors.

Another favorite of mine for headlights are 2mm LEDs with square bases. For HO when fitted next to each other the spacing is just right for the common double headlight and the top of the LED fits into the lamp hole. They are a lot easier to wire.

Mike Ruby