Looking for led advice — Update

I would call Dave at Evan Designs and ask him what to use.

Dave is not cheap but we have hundreds of his LEDs and they continue to work.

Why wouldn’t a chip LED work well?

Good luck. Like the lights.

I’m not sure I can solder an smd. 

I think that a chip LED, or maybe two would be the ticket in that fixture.  They would shine down and also have a wide angle dispersal of the light.

John, pardon my ignorance, but is a chip LED the same as a SMD?

You can get a chip LED; AC/DC, 7-19 volts, 8” wire, minimum of 5 for $3 each from Dave. Get 10 and up and they are  $2.90.

You can solder the wires to the power source or he will tell you how you can use shrink tubing and not solder.

If you get other voltage the price can be as low as $2 each. I like the flexibility that the 7-19 gives for multiple applications.

If you ask, he will probably send you one to try out if you are going to order quite a few.

Yes, an SMT LED or "chip" LED is what is on the LED strips that are so common nowadays.

Thanks. I already have some 5730 LEDs coming, so I'll test my skill on wiring them.

Big suckers, you should be able to solder to those!   Use minimal heat, no more than about 500F, 260C.  This is from the Everlight spec sheet.

Thanks, John. I thought I'd start big and work down.

You might look at automotive (12V DC) LED bulbs constructed using multiple boards in short strips.  The LEDs are packed together much closer than on 12V LED strip tapes where it's typically 3 LEDs every 2" (5 cm) or double that for double- density.  But strips aren't necessarily designed for narrow width which I think you'd need.  Obviously the bulb boards must be narrow width to wrap around these bulbs.  Point being you might not have to deal with soldering individual chip LEDs if you can find, say, a narrow board with 3 LEDs already installed.

Stan, any of those bulbs will be huge for the task at hand.  This lamp fixture is pretty small.

I mean just extracting one multiple-LED "panel" from a bulb.  As I understand it, the available cavity is about 1" x 1/8" (25mm x 3 mm).  So, for example,

The big application seems to be automotive so presumably each of these "panels" operates at 12V DC which should be easy to generate.

Another packaging technology are so-called filament LEDs that look like a burning filament.  But I couldn't readily find a short one.

As a last resort, if having to assemble individual chip/SMD LEDs, the challenge is a mounting scheme.  To that end, I suggest using so-called "scissor-cut" circuit board which is thin (e.g., 1/64") copper-clad and hence cuttable with a scissors.  Use a hobby-knife to score the copper to create electrically-isolated islands.  This gives a substrate to mount and solder the chip LEDs in arbitrarily tight spacing.  This photo was for a different application but should illustrate the idea.  In this case there's just parallel tracks so all the LEDs would be in parallel with 2 wires off the end of the board which would have ~3V DC.

Scissor-cut circuit board is available in single-sided or double-sided.  So the double-sided is a thin layer of copper, an insulating non-conductive substrate, then another thin layer of copper.

Truthfully, I'd seriously consider a PCB, get a .031 thickness the shape needed.  Piece of cake at that point.

OK. I got a .5 meter strip of 3528 LEDs 240 per meter. I cut a section of two sets of three, soldered wires, and replaced the bulb. That draws about 50ma, as compared to 900ma for the bulb. All four draw about 200ma, as compared to 3600ma for the bulbs. The cost was $1.27 for the strip; the wire I already had.

Nicely done, John!

The 3.6 amps for four lamps is mind blowing!  I have a bunch of those lamps, I'll have to look into a similar mod.

John, you’re right. I was off a decimal point. 90 ma is what they are, 40ma for the six LEDs. Hope your mind is ok😉

That sounds more like it!  I was thinking about 12 watts in that tiny lamp and wondering how long it took to melt the plastic shield.

Out of curiosity, why did you go with 2 segments (6 LEDs) rather than 1 segment (3 LEDs).  That is, you only cut your current in half (from 90 mA to 40 mA).  Usually one can expect a 5-10x improvement in power for the same brightness when going to LEDs.  

Anyway, I'd think that using just 1 segment (3 LEDs) or 20mA would still be brighter than the lamp. Seems from photo the 6 LEDs are much brighter than the original bulb - of course that may be the effect you wanted.

Stan, I used 2 sections because it was a perfect fit. They are very bright. I figured it would be easier to just snip three off as opposed to adding the extra set to the first three. At the 12 vdc that I use for all my lighting and most accessories, the bulb was very dim. I'll have to install one and make a decision.

John, I know you have some buck converters, can you cone down the voltage to taste with one of them?  Or go the diode route.

Those are options I thought of, also. The six fit perfectly in the housing, so they might be better than cutting three off.  Thanks , Ted.

The bulb was dim because it's an 18V bulb!   For the LED's, you could just drop in a 56 ohm 1/2W resistor in series with the lamp, that should tone it down some.  If it's still too much, go for maybe 100 ohms.

3528 LED's packed 240 per meter--WOW!

Thanks, John. That would certainly be an easy adjustment. By the way, you certainly look different without your glasses!

Well, it did happen I didn't have the glasses on, that was a recent shot at the NJ-HR.  I still wear the glasses most of the time.  After my cataract surgery, I have good distance vision, just can't see things close now.  It used to be the other way!  Does this make it easier to recognize me?

I put one on the layout.  Bright, but looks good lighting the corner. 

Yep, it's bright!

I think you did such a bang-up job that this ought to be thoroughly documented for posterity (i.e., easily search-able).  

To that end I was trying to gather some words/phrases/numbers so the search engine could find it.

What's confusing is the Lionel manual for #72 Highway Lights, SKU 6-12804, says replacement bulb is 610-2804-301 but web search gives conflicting results for that number including a bulb that looks nothing like your photos.  OTOH Town and Country site has at 14V bulb number 10-2804-300 which does look like your photos. 

Nowhere could I find the dimensions of the bulb.  Perhaps you could document that since presumably you now have some sitting on the bench.

The 240/meter LED strips are fairly easy to find $1-2 on eBay for a 0.5m strip, free shipping from Asia.  Available in cool or warm white.  0.5 meters => 120 LEDs => 40 x 3-LED segments, each segment is 1.25cm long (1/2"), per specification below the strip width is 1.0cm and height is 0.3cm).

Note "working power" is 60 Watts/5 meters...or 6 Watts for a 0.5 meter strip.  40 segments so 0.15 Watts for a 3-LED segment or 50 mW per LED.  Assuming 12V DC, LED operating current is 12.5 mA which sounds about right.  "Brightness" of 4 Lumens per LED suggests an output of 80 Lumens per Watt which again sounds about right...maybe a little ambitious...for consumer-grade LED strips.

I bought my pile of these lights in a box with a bunch of other stuff, but they obviously have the 18V bulbs as they're at normal brightness (and certainly not visibly over voltage) at 18-19 volts from a bench power supply.

Following up with some measurements on the "high density" LED strips John H used for his highway lamps.  To be clear, this is not your father's Oldsmobile.  

Most guys are familiar with the standard 60 LEDs per meter strips - where each 3-LED segment is 5 cm (2-inch).  This works out great for passenger cars where you might use, say, 6, 7, or 8 segments to span a 12", 14", or 16" ceiling. 

But to state the obvious, if you only need to light up a small area such as a vestibule, and don't want to fuss with individual LED's, then these high-density (240 per meter) strips might apply.  One segment is only 1.25cm long x 1.0 cm wide.  They are also remarkably thin - less than 1mm or about the thickness of a dime (thinner than a penny)!  Yes, I realize lots of guys are experimenting with individual pre-wired surface-mount LEDs to light up small areas.  But it just seems there's endless hand-wringing over choosing the right resistor or what not.

Each 3-LED segment has a built-in resistor that makes it compatible with 12V DC (nominal full brightness).  You can hook it up directly to GRJ's lighting module (see photo) without fussing with an LED calculator to choose a resistor value.

In case it's not obvious, you could use GRJ's lighting module to power up, say, 7 segments of a standard 60-LED/meter strip for a passenger car...and then tack on 1 segment of a 240-LED/meter strip to light up a small room, door entry, vestibule, whatever.

For inquiring minds, here's some data I took on a 240-LED/meter warm-white strip with the 3528 (3.5mm x 2.8mm) LED as shown in an earlier photo.  It really doesn't show anything new - that is, this data should jive with other 12V DC LED strips discussed on OGR.  Note the data is normalized to one 3-LED segment.  So, for example, applying 10V, the 3-LED segment draws ~6 mA (blue curve), each LED also sees ~6 mA as the 3 LEDs in series, and each LED sees ~3 Volts (orange curve).  Note that since 3 LEDs x 3V is only 9V, the remaining 1V is the voltage drop across the surface-mount 150 Ohm resistor on each segment.

Just got these 5050 leds, 120 per meter. These will really light something up!  It appears that each one is three smaller leds. 1.3 amps per meter. Thought they would be interesting to experiment with.