Got it, thanks so much.
RicZ
1/8 watt resistors are plenty big enough for this purpose. With approximately 9ma going through them, the resistors are dissipating less than 1/10th of a watt.
The green wire on a T1 isn't connected to anything. Only the yellow and white. You need a T4X to get a green and purple wire that actually do anything. T1 only has 2 functions, forward and reverse light. T4X has forward and reverse light plus 2 additional functions.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy, thanks again. Two final questions (I think). 1. Does the resistor wattage need to be equal to 1 watt or is a half watt OK on the 1K resistor? 2. Can the TCS T-1 green wire really be remapped to another function code since it is a 2 function decoder? (TCS FAQs say, No, but maybe they are just trying to sell another unit.
Despite havign them configured for directional lighting, I alway suse a resitor with each LED. SO a 1K and LED connected to the white and blue for the headlight, yellow and blue for the reverse light, ad then you cna use green and blue or purple and blue for the LEDs in the interior, that would default put them on F1 or F2 but they can be remapped. For the interior lights, 3 or 4 LED/resistor pairs, each pair wired in parallel to the others.
I know the first reply is goign to be "but if you put the LEDs in series..", Well, one resistor per LED is AlWAYS safe, and resistors are cheap. Especially since 1K works for every whte LED with DCC I've ever come across, you cna buy more than just a 2 pack at Radio Shakc - you can get a box of 100 from Mouser for about 4 cents each. For 4 cents, just put a resistor with each LED and don;t wworry. If you're paying 50 cents a resistor from Radio Shack, well, no wonder you'd want to use as few as possible.
Thanks, Randy. As always you are a great help. I assume that if I use teh T-i decoder and only change the front and rear bulbs to LEDs that teh 1K resistor will support them with sufficient brightness. (in lieu of a single 470 ohm. True?
Yes, you need to step up to a T4X to get the extra function for controlling the interior lights.
I'd use 1K resistors, 470 ohms is too low for a white LED. 470 ohms at 12 volts is almost 26ma, the limit on most white LEDs is 20-25ma. 1K resultes in about 9ma and PLENTY of brightness.
So 18ma for the headlight and rear light, and another 36ma if you put 4 LEDs with resistors in the passenger area. All easily within the function output limits of the decoder. There are usually two numbers, one is the maximum current per function wire, the other is the maximim total for all function outputs.
MisterBeasley, you are right. I rechecked the T-1 Data on the TCS web site and confirmed that this cannot be done with a T-1 decoder. I didn't go far enpugh in the tech data. The T-1 manual didn't give me a clear picture, but TCS's FAQs did. Thanks.
From quickly reading the description of the T-1 decoder, I don't think it has any function outputs other than for the front and rear lights.
Is your plan to use the same function output for the headlights and interior?
It takes an iron man to play with a toy iron horse.
1. I prefer putting them in parallel with each LED having it's own resistor. You can come off of the one wire for all 3.
2. Keep in mind that the voltage out of the decoder is a function of it's input voltage, so it could be more than 12V for example. Because of this and different light brightness desired, I use 470 to over 1000 ohms per LED--just depends.
3. Be sure and use heat shrink tubing or something to insulate the exposed wire/solder.
4. Also, since LEDs tend to have a focused beam vs a bulb you may want to use a reflector to avoid lighting "hot spots". Actually I think this is good practice for car lighting regardless of LED vs bulb.
5. Make sure that decoder is a function only decoder, or else you'll have to use a resistor across the motor leads.
Richard
Good evening. I am trying to determine how to wire a TCS T-1 decoder to an RDCan use the F1 function for interior lights. I have some Minitronics 3.4 vdcLEDs and associated resistors. I have read the article in "WiringForDCC" butthey don't mention the interior.- If I use 3mm white LEDs with 470k resistors for the front and rear light, whatis the best way to provide the interior lights using white LEDs?- What size resistors for the interior?- Wire 2-3 LEDs off the green wire, wiring the LEDs and resistors in parallel orseries?Could use some help here. Thanks in advance,RicZ