N Gauge Kato Observation Cars and LED Lights for Markers and Drumhead

[Bart1701]

I have the Kato N Gauge Super Chief passenger cars that includes the Observation Car. Kato supplied it with an LED light assembly that illuminates the marker lights and the drumhead.

My layout is DCC and I am wondering if it is safe to use the supplied LED with DCC.

I had heard stories of the lamps (including the older Kato passenger car lighting kits, too) getting warm enough to soften/melt the plastic bodies...so, I had pulled the LED assembly out from the observation car just to be safe.

I have since installed Kato passenger car lighting to the cars - using their new DCC friendly LEDs. The lights look pretty good!

But now the observation car is desperately calling out for the marker lights and drumhead to be illuminated.

Any thoughts?

Thanks,
Bart

[peteski]

It is perfectly safe to use any of the LED-based lighting kits (or lighting included in Kato cars) with DCC.  They have a built-in rectifier (which will properly power the LED) and they have a current-limiting resistor included.

The old Kato lighting kits used a standard 12V light bulb which powered from DCC was glowing full brightness. Some DCC systems were even over-driving the bulb with a voltage greater than 12V.  At that point the bulb generated enough head to eventually melt the plastic rood of the cars.  That was the problem.  LEDs run cool and they will not cause a meltdown even when powered with little more than 12V.

[Bart1701]

I am not sure if I was technically correct in referring to my lights as LEDs (blame it on my lack of electrical knowledge). To me, any tiny little light is an LED - which I know is wrong.

I had to order a new light board from Kato since I was unable to figure out where I put the original board when I removed it from the car about 12 years ago!

The new board arrived and I have attached some photos of it. They are about as close as I can get with my camera. How do I determine if it is an LED or a Bulb? Or do the photos give you enough clues to tell me?









Also, I see that Kato has this item listed on their site. I am interpreting this item as a way to control whether the Red marker light or White backup light gets illuminated on the car with a DCC setup.  If the board actually has a bulb instead of an LED, I am not interpreting that this device does anything to decrease the power going to the bulb to reduce the amount of heat it generates - does that sound right?



Thanks,
Bart

[peteski]

Yes and yes.

Those are LEDs and the lighting function decoders are simply to enable DCC control of the lighting boards.  Theoretically the lower the DCC voltage slightly as couple of transistors are inserted into the current path. But that is really unintended feature and it has a negligible effect on the brightness/current-consumption of those LEDs.

Make sure that you get the right decoder (the one you circled) as it is a non-standard decoder. I have never used it but it appears that it achieves control of 2 functions by flipping polarity of the voltage going to the light board. A standard 2-function decoder would not work in that circuit.

As far as identifying LEDs and bulbs, light bulbs have glass bodies and a thin wire filament inside (supported by thin wire leads).  LEDs have resin bodies and rectangular cross-section leads. Inside of the body one lead extends into a larger "flag" while the other lead remains small.  The body usually has a rim which has a flat on it near the negative lead. The "flag" part also generally (but not always) denotes the negative lead.

Light bulb aren't polarized (they will light up regardless of the positive/negative voltage applied to them).  LEDs are polarized and will only illuminate by being properly hooked up to the positive.negative of the power source.

[Bart1701]

Thanks, Peteski !

The light is installed and working great in the Observation Car now.

I appreciated the tip about how a bulb will light regardless of polarity of the wires, and an LED only lights with the correct polarity applied to each post. I tested this myself with a bulb and an LED; this bit of knowledge is now firmly etched in my brain for future use. Also appreciated the explanation of the physical differences between a bulb and an LED.

Bart

[peteski]

You're welcome Bart!  Knowledge is power (if used wisely).