Up gradeing n scale old Kato units I am also upgrading to leds, my issue is getting them to work. I am putting the resister on the neg side of the led on both the front and rear lights. the decoder is just a generic using yellow and white with the blue for ground. I just started converting them over....still new at this . except for the lights the unit runs right. I am using a 15k resister.
15K ? Try a 1K resistor...
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Or even a 2K.
15 K is WAY too much.
It has been a while since I wired one but I think the Blue wire is the + side and the White the - side for the front and the yellow the - side for the rear lights.
Slim
Yeah, with 15K - that's .8ma at 12V. In a darkened room you MIGHT see the LED glowing slightly with that low a current. If 1K makes them too bright (still well below the maximum current limit), try bigger, 4.7K, or even as much as 10K, 10K is 1.2ma and a very efficient LED should have a decent glow.
The blue decoder wire is actually the + side of the circuit and go to the + side of the LED. The white and yellow wires are the - in the circuit. It does not matter which side the resistor goes on, but you should strive to be consistent.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
will try that....This converting is all new to me.... I still have to use two resisters for the front and rear light. Correct
I have a couple of I can unsolder from a dc board I replaced with a drop in from a Atlas engine. Or do you think That the resister would be too high?
Resisters all have colored stripes around them. This is color coding to indicate the amount of resistance, measured in Ohms. If you google "resistor code" you will find several sources for charts showing the color coding. Use one of them to determine the resistance of the resistors on the DC board.
The resistors on the DC board are likely too low a value - you need the lights to come on at less than full throttle so the resistor is sized based on less than 12V going to it, with DCC the power is contant, commonly around 12V for the N scale setting if the system has such a setting.
Resistors on an N scale circuit board will probably be surface mount. They do not have color bands. Typically the first 2 digits are the value and the third digit is the number of 0's. So a 102 would be 10 + 2 0's, or 1000 - 1K. 471 would be 470 ohms. 472 would be 4700, 4.7K. Etc.
Calculator here: http://www.hobby-hour.com/electronics/smdcalc.php
Hi wilzdart:
Rather than salvaging resistors you can buy them for peanuts on eBay or from Digi-Key, All Electronics etc.
http://www.allelectronics.com/make-a-store/category/530200/resistors/1/4-watt-resistors/1.html
Buy yourself a small assortment:
470 ohm
1000 ohm (1K)
2200 ohm (2.2K)
3300 ohm (3.3K)
4700 ohm (4.7K)
7500 ohm (7.5K)
10000 ohm (10K)
22000 ohm (22K)
30000 ohm (30K)
You will use the 1K the most by far. I would only buy 10 or 20 of the others to start.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Check the instructions for your decoder. Some have piece of tracing ( the conductors on the pc board ) that can be cut with a sharp knife. This puts a resister in series with the LED so no external resister is needed. Super easy.
I'll just add that the resistor can go on either the positive blue or the negative wire. Your choice.
Yes, you should use a resistor for each LED.
You can also use half wave lighting. Anode gets connected to one rail. Cathode gets connected to the proper negative direction wire, (White or Yellow). You still need the resistor. With half wave, directional lights will work but special effects will not be possible. It will just be on or off depending on direction.
Martin Myers
thanks for the place to buy them as a newby in DCC.. this is great you guys helping me.
Ok I used a 680 resister used the blue wire and the plus side of the led used a heat sink to solder it up but I am only getting one lit the other does nothing. It is wired the same. So what do you think is wrong. I did use a mulitmeter to check led before I installed them
Thanks for the suppler for resistors.
checked out your site some of your links do not work but you stuff looks great