Can these LED lights be connected to a AC transformer without modification?
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NO YOU CANNOT , and LED is a diode. the characteristic of a diode is that only passes current in one direction. forcing current on the wrong direction will greatly shorten the life of the LED. also the forward voltage of an LED is typically 1.7 to 3 volts DC only. you will need a resistor to drop the supply voltage down to the forward voltage of the LED and if you are using AC from your track power you will also need a diode as a rectifier.
From the product description linked: "1 LED = 20 mA / 3 volts". Bill R. has the nuts and bolts of it.
Also for what it's worth you can buy the 12v LED strips that are often discussed for use lighting passenger cars, and get 30+ LEDs for the price of the linked 4 pack. The Hennings module is an off the shelf solution to allow you to power these light strips from track/transformer power. http://henningstrains.lightspe...ng-kit-jwanda/dp/253
JGL
Thank you!
when buying LED strips made for train passenger cars they will have the necessary components integrated into them to a accept 18 VAC. if you want to make your own LED to connect to track voltage (18VAC) you will need a 820 ohm 1/4 watt resistor and 1N4148 Diode (LED an AC Rectifier Universal diode). if you are using a 12 volt DC power supply than you only need a 470 ohm resistor is series with the LED to get to the necessary voltage for the LED. you can search on Ebay for the parts, you can get 100 resistors for $1 to $2 and the 100 4148 Diodes for around $14.
However, if you want no flicker lighting, you need to add a capacitor. Also, for DCS compatibility, you need to add a choke as well. Here's what is in the module that JGL linked to. Besides the choke and capacitor, it has an intensity adjustment. I use constant current to power the LED's, this allows a finer intensity adjustment, as well as compatibility with single LED's if desired.
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I bought a 15 foot long LED stripe lighting 12VDC for $6. you can cut it as small as two inch increments if you like. you will also need a resistor to drop from 18 volts track power to the 12 volts needed for the tape LED's and also rectify it to get DC. you could do 15 lineal feet of LED lighting for $12 in parts
Gunrunner
you are 100% correct. my illustration was to answer the original basic question of "do you have to modify an LED to connect it to track voltage. with a little home work and a sprite of adventure you can build your own lighting systems for substantially less money than a prepackaged solution and have fun doing it.
I suppose my answer is also based on the question asked... It's not my intention to knock the OP, but when very basic electronic questions are asked, I tend to assume that the poster has zero skills in electronics, so the simplest solution is the one I'll go for under that assumption.
There are many ways to skin a cat here: one could also use the power supply and control system for Light Genie, rather pricy for what you get, I think, but you don't need to do anything. The Hennings module is a turn key solution that most folks can set up without trouble, though it is also relatively expensive compared to putting together your own components. For my own use, I would probably use a computer power supply to provide 12v to as many light strips as I could stuff on the layout, but this has the down side of requiring a separate power bus for lighting.
JGL
I am using a PC power supply for all my lighting as JGL suggests. You can wire the led strips directly, you don't have to rectify for other leds, and incandescent building lights look softer. You can share the ground on the layout if no items need an isolated supply. I have two; one used from a computer repair store for $15, and one from a computer tossed at our town recycling center. The price was just right on that one. At 300 watts each, they can light a lot of lights.
