RailPro > Finished RailPro Installation Examples

Adding Lights to Genesis Board

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KPack:
Dan, I'll respond here rather than email so we can get the information out there for others. 

I've never wired a 1.5v bulb to a resistor because I always change them out in favor of LEDs.  I'm honestly not sure of what resistor to use in this case.  For LEDs I use a 1K ohm 1/4 watt resistor.  LEDs I believe typically run at 3V or so, so perhaps a bit bigger resistor for the 1.5V bulbs?

My vote is to start your LED conversion early and just pop two LEDs in the ditchlights.  That way you only have four more to change later.

-Kevin

drisdon:
This is not a bad idea...and maybe change the rear headlight at the same time.  At least when viewed from the rear the color would all look the same.  It's not like I don't have the LED's, I just thought adding 2 bulbs would be easier.  When I connected everything yesterday I really didn't like how dim the headlights were with the bulbs, so LED's would definitely brighten it up too and make it much longer lasting and uniform.

Thanks for adding to the workload!

Dan

KPack:

--- Quote from: drisdon on February 28, 2018, 03:58:52 PM ---Thanks for adding to the workload!

--- End quote ---

Just doin' my duty.  8)

It just makes more sense to put the lights in one time....if you do bulbs you'll have to change them out, and you won't be happy with how dim they are.  Do it right the first time and save yourself the trouble later!

-Kevin

Alan:
If you do decide to use 1.5v bulbs with LM output you will need a dropping resistor. If the bulbs are 12v or higher then no resistor needed.

To determine the resistor value needed you must know how much current the bulb draws at 1.5v either by measuring it or from the manufacturer's specs. Once you know the current then use Ohm's Law to determine the resistor value.

Resistor value = (track voltage - bulb voltage) / bulb current. For example if the bulb draws 15mA at 1.5v then the formula is (14.8 - 1.5) / 0.015 = 887 ohms. Closest available resistor value = 1000 ohms. Higher value resistors will make the bulb dimmer.

Once the value is determined you need to calculate how much power (heat) the resistor will have to dissipate. The formula for that is (track voltage - bulb voltage) * bulb current. For our example 15mA bulb the formula is (14.8 - 1.5) * 0.015 = 0.2 watts. Closest resistor rating is 1/4 watt (although that is cutting it close, better to use a 1/2 watt unit).

Kevin is right. Bulbs have a short lifetime, LEDs have a very long lifetime. Go with LED unless you really need the incandescent "look" which is totally understandable on a locomotive. Prototype are not LEDs (yet).

Dean:

--- Quote from: drisdon on February 28, 2018, 11:55:25 AM ---KPack solved the mystery, the 9 pin harness only supports four functions, front headlight, rear headlight, and 2 front ditch lights.  So I have to hard wire the rear ditchlights.  Will 1K resistors work with the Athearn bulbs?  I usually use LED's so not as familiar. 

Dan

--- End quote ---

Couldn't you use the six pin connection to get more outputs?

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