Help with LEDs to Replace Grain of Wheat Bulbs

Evan Designs is all I use for LED’s. Chip lights might work in those. 

https://evandesigns.com

Evan Designs shoudl have what you need.  If not try RoyZ

Nice marker lights

I think a wide angle flat surface led would be easier to aim and mount there than a standard "bulb" type led., which projects dead ahead. Even with a wide beam they can pita on lamps

Bob,

I'm working on doing the exact same thing as you, on a K-Line caboose, removing the old light board with it's seven incandescent bulbs, and upgrading to LED's, using Henning's Trains LED driver developed by Gunrunnerjohn.

The bulbs used for the K-Line marker lights are also 2mm wide. I too looked for a comparable size dome-top round LED. There are 1.8mm size versions, where the top is 1.8mm in diameter, they have a rectangle base that is generally 2.4mm x 3.4mm, too big to fit into the market light hole without some kind of filing modifications to the LED. So I wondered if one of the chip LED's I have from Evan Designs would fit and light the 3-sided marker light OK. These chips are 3.2mm long by 1.6mm wide, and when you bend the wires a bit, makes it the same profile as the 2mm grain of wheat bulb - see below.

So I tried it, to see if it would fit, and then what would the lighting look like. It slides right in, no problem with no mods.

Now I powered it to see how well this one-sided chip LED would light the 3-lens market light. Not too bad in my opinion.

Depending on how this one direction chip LED is inserted / positioned on the marker light, the emitted light can be directed more towards the rear-facing marker lens, or the front-facing marker lens. In my trial, the front-facing lens is a bit dimmer than the yellow side lens and rear red lens. But again, not too bad.

Pushing further, I want to try something else. What I'm going to do is try another Evan Designs LED I saw on their site, the "Full brightness all around Double LED". This item is "2 LEDs, soldered close together, then folded them over to put the two LEDs back to back" to give a 360 degree glow. Image below from Evan Designs' site.

There is a Pico size, and a smaller Nano size. Doing some calcs I think the Nano size will fit into the market light holes with no problem. So I ordered some Nano double LEDs and am waiting for their delivery to try them out. I'll follow up on this thread once I get them.

Tom

Thanks Tom.  I was looking at those full glow LEDs after Chris and Steve pointed me to Evans. The 12 volts from John’s board is too much for the 3 volt LED, but maybe wiring them in series and/or adding a voltage drop diode or resistor will do the trick.

Bob,

Correct those double-sided, full glow LEDs are 3v. So I also ordered this $2 separate rectifier unit below from Evan Designs to go with 'em. This single rectifier will be able to power two of the full glow LEDs, one for each marker light, which is actually four nano LEDs. This way I can connect this rectifier unit directly to the 12v output of the Henning's LED driver. Could have done it also with resistors or wiring methods as you mentioned, but this was the no rigmarole, low-hassle route I took. These parts arrive today - we'll see!

These are some of Evans LED’s I put in some of my subway cars. 

Bob, you're wrong!  My LED regulator module is a constant current design.  It delivers whatever voltage is required for the load.  If you have a couple of 3V LEDs, it'll run them perfectly.  The pot that adjusts intensity varies the current from around 3 milliamps to around 45 milliamps.

gunrunnerjohn posted:

Bob, you're wrong!  My LED regulator module is a constant current design.  It delivers whatever voltage is required for the load.  If you have a couple of 3V LEDs, it'll run them perfectly.  The pot that adjusts intensity varies the current from around 3 milliamps to around 45 milliamps.

So, if I hook up the three Evans 3V LEDs (for the markers and drumhead) in series and hook that up in parallel with the light strip (for the interior passenger area), I’ll be OK?

You need the bare LED's, most of the Evan's stuff has provisions for track voltage.   If they're bare LED's, you have it right except for one thing, you'll also need a load balancing resistor in series with the three LEDs.  Note that the LED strips have three LEDs, but they also have that little resistor for each three LED section.

For what you're doing, I'd start with around a 1K load balancing resistor and see how you like it.  I've gone as high as 3.3K for similar applications as the markers and drumhead don't require near the intensity that lighting the main passenger compartment does.

Bob,

My follow-up. Received the nano size Full brightness all around Double LEDs from Evan Designs. They're small alright. About 1mm wide. The pico size probably would work too.

But still bright. And this is with the camera flash on.

Fits right in the old bulb slot fine.

Now the acid test - powered up and they light up the marker lights perfectly, rear, side and front lenses all the same intensity.

Tom

Thanks Tom.  That looks great.  Did you use the Evans rectifier connected to John’s LED regulator?

You do not want any extra baggage for the regulator.  However, I don't know how the Evan's LED is wired, if they wired them back-to-back in reverse to run on AC, only one will light on my regulator.

I finally got around to wrapping up this little project.  I used the JWA regulator for the passenger compartment and copied what Tom did for his caboose markers.  I fed track power to a $2 Evan Designs regulator to power 3 of their double sided nano LEDs in parallel for the markers and drumhead.

Lookin' good, nice intensity on the drumhead, not to bright and washed out like many of them are.