HO all the way!
Im curious if its possible to have loco lighting in a dummy without a decoder? Ive been using 0402's and wondered if I could wire em to a rail wiper with a 1000K ohm resister?
That's a maybe. First, since you mentioned "a dummy without a decoder", I assume you're talking about a DCC system. So the rail voltage is from 15V to 24V depending on your system and settings. Next, you'll need the datasheet on your LED. The first one I checked runs at 3.00V max with a current draw of 126mA. With 15 volts to the rails, this would require a 96 ohm 1.5 watt resistor. A 1000K (1Meg ohm) or even a 1000 ohm resistor would drop the voltage below the LED's minimum operating voltage.
Im using the SM0402's that I solder magnet wire onto. These I believe are 3.2V max and yes, it is an NCE DCC system. So I would be pretty close with a 100 ohm resistor for each?
Whoa! For the small LED's we use in locomotive lighting, 126 ma is a LOT of current. Most of them have a max of around 20ma. Also, the current rating of an LED is it's MAX rating
Additionally, the resistor does not drop the voltage, the LED drops the voltage.
...rong. Please review Kirchoff's law...
RailroadBookstore.com - An online railroad bookstore featuring a curated selection of new and used railroad books. Railroad pictorials, railroad history, steam locomotives, passenger trains, modern railroading. Hundreds of titles available, most at discount prices! We also have a video and children's book section.
ModelRailroadBookstore.com - An online model railroad bookstore featuring a curated selection of new and used books. Layout design, track plans, scenery and structure building, wiring, DCC, Tinplate, Toy Trains, Price Guides and more.