I have been completely through Digitrax website with no luck. I am wanting to install some extra lighting on a few of my N scale Digitrax decoders. I have all my equipment and parts, now I can't find info on the voltage that is supplied from the FX3 function outputs. I need to determine which resistors to use to protect my led's but, I can't find the voltage supply rating for the decoder FX output pads, I've tried reading the voltage with my meter but I just keeps faulting my system and not giving me the info. could someone please fill me in on the voltage supply? thank you for any replies.
Standard NMRA compliant function output should be 12 volts. As David mentioned, a 1K resistor will work fine. What Digitrax decoders are you working with?
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
jrbernier Standard NMRA compliant function output should be 12 volts...
Standard NMRA compliant function output should be 12 volts...
No. Some decoder outputs are regulated but the vast majority of them are powered straight off the bridge rectifier which will give track voltage minus ~1.5 volts.
Thanx guys, now I guess I have to order some smd 1k ohm resistors, I just have 470 ohm. I am going to use 603 smd golden whites. I'm going to cut the factory light pipes, add the smd led's to the inside end of each pipe and secure with tiny shrink tubing, it really pipes the led light out great. I have looked all over the net for a good tutorial to add operating ditch lights to N scale locos, but all I find is people advertising to install them for a price. I want to find a good way to do this and post a tutorial after I simplify it, a lot of people are like me, they like to learn how to do things for themselves instead of always hire someone else, it's a learning thing and an accomplishment thing.
What type of decoder(s)?
What kind of LEDs?
Rich
Alton Junction
Digitrax dn163k2
0603 smd led
richhotrain What type of decoder(s)? What kind of LEDs? Rich
Those are very bright LEDs. 1K resistors would be OK, but I have used as much as 3K resistors to tone down the brightness.
The Digitrax mobile decoders, including the DN163K2, have 500 ma. function outputs, so that decoder will support a good number of SMD LEDs.
should I use smd resister or axial carbon films, what's your opinion?
I use 1/4 watt carbon film resistors with my surface mount LEDs.
Depends on what you have room for. I'm in HO so I just use axial lead carbon film resistors. In toght spaces for smaller scales you might want to use SMD resistors just so it all fits.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I wish there were open printed circuits between the functions outputs and the actual function output solder pads, for easy on board installation of smd resistors, and if you added a function that didn't require voltage drop you could simply bridge the pre printed resistor traces.
See if TCS has a decoder for that loco, many of theirs have the resistors built in. Works the other way though - if you DON'T need the drop, you bridge two pads with solder to bypass it.
Thanks Randy, I'm still fairly new to DCC operation and I'm trying to crash course everything, nice site and layout by the way.
CSX Robert jrbernier Standard NMRA compliant function output should be 12 volts... No. Some decoder outputs are regulated but the vast majority of them are powered straight off the bridge rectifier which will give track voltage minus ~1.5 volts.
That is the 'unloaded' voltage - Under load my test DH163 drops to 12.2 volts. I suspect most decoder function outputs are non-regulated.....
The regulator on the decoder is 5V,or maybe 3.3V, to power the microcontroller. Functions just get rectified DC from the bridge. Need proof? Look where you get the positive source for a keep alive, the blue + common wire. If this were regulated, it would be after the regulator, but it actually goes right tot he + side of the bridge. ANd for those decoders that do not have a connection, you tap in to the - side of the bridge for the - terminal of the cap.
jrbernier CSX Robert jrbernier Standard NMRA compliant function output should be 12 volts... No. Some decoder outputs are regulated but the vast majority of them are powered straight off the bridge rectifier which will give track voltage minus ~1.5 volts. That is the 'unloaded' voltage - Under load my test DH163 drops to 12.2 volts. I suspect most decoder function outputs are non-regulated..... Jim
No, I am talking about the 'loaded' voltage, although the difference in voltage drop will not be significant between a loaded output and an unloaded output. If your decoder output is 12.2 volts, it's not because an NMRA compliant decoder necessarily has a 12 volt output, it's because your track voltage minus the voltage drop through the decoder equals 12.2 volts.
Most DCC systems setup for N or HO scale have a track voltage in the 14-16 volt range because that does get the maximum motor voltage and function outputs into the 12 volt range, which is what most N and HO scale locomotives are designed for. The allowed range for DCC track voltage, however, is 7 to 22 volts(depending on scale), so you can have an NMRA compliant decoder running on an NMRA compliant DCC system with an unregulated function output of anywhere from ~5.5 volts to ~20.5 volts.
Thanx everyone for all these posts and this help, I have another question. In order to wire one set of ditch lights, would I have to use two function pads, say F1 and F2, not including the blue common +. Or could I wire common + (blue) and the two ditch lights in series into F1, would I still be able to alternate flash or would they flash in unison at the same?
For alternating flash, each LED has to have its own function. If you connected both to F1, then they would only be on or off, or flashing in unison. The way it works, the 'flashing light generator' part of the decoder obviously has an on and off position - well, you can assign the 'on' side (some call this Phase A) to one function output, and the other (Phase B) to a second function. So when one is on, the other is off, and vice-versa.
Ok, finally got my first N scale ditch light project done, what a huge headache to be such a tiny job. I learned a lot that will make the next one much easier. The one part I struggle with so much is, soldering magnet wires. No matter what process I use to prep the magnet wire, it never holds the solder, I've tried using seperate flux, I've tried stripping the enamel with hot solder and with a lighter, I can't find anything that works good.
i think the enamel will burn off, but i always scrape it off with a razor blade
Am i ever gonna be able to lay any track???
I completely remove the enamel and still no luck, I can solder it to something, the solder will completely surround the wire, but after cooling the wire will slide right out of the solder leaving a tiny hole, it just won't stick to it, and I know my iron is hot enough, I use a butane iron, I've tried very low heat and super high heat
are you sure you got the enamel off? can you check it with a magnifying glass?(you should be able to see copper)
what your describing sounds like a cold solder joint, but if the enamel is there you may be hot enough...but if you are that hot, it seems it would melt the enamel...
i use a weller iron, about 700-800 degrees...i`ve never used a butane iron, do you have some specs on it`s heat output
how hot is "super high heat"?
1,022 fh
I wouldn't use one of those butane irons to solder wires to decoders and LEDs, especially surface mount LEDs. I'm surprised they work aftwerwards, the heat is too high and the tip is too large.
The trick is to tin the wire, so there is a small blob of solder already stuck to the wire. The old way to clean the wire was to squeeze the end with sandpaper and pull, but even just the heat should clean it off. The enamel coat is very thing, which is why you have to handle the wire carefully, it's easy to get a short because you scrapped the coating off accidently. Are you sure you have the right type of wire? Solder should have no problem sticking if the enamel is off, underneath it should just be (fine) copper. What this tells me is that the wire itself is probably not being heated when you solder, probably because the tip of your iron is too large to contact such a tiny piece of wire and the terminal at the same time.
When I try to solder something as small as an SMD, I use an Optivisor. Amazing what you can see with an Optivisor that you cannot see with an old naked eye.
You should be using 60/40 Rosin Core solder for what you are doing. 60 lead/40tin, sounds like you are using the wrong solder and thickness/diameter of solder.
Frank
I think Randy is on target here, you may be using a lot of heat, but it seems it is just not getting into the wire. I would definitely tin the wire first. To be clear, when you tin the wire you want to make sure you melt the solder with the wire, don't melt it with the iron and have it flow on to the wire. I usually put a tiny blob of solder on the iron to help with heat tansfer form the iron to the wire, but then I make sure the wire is hot enough to melt solder directly onto the wire.
I am using 60/40 rosin core, very fine dia.. I'm beginning to think it's the type of magnet wire, I bought it off of the internet from an industrial supply and it has never done good. I am going to stop at the Shack in the morning and pick up some of radio shacks magnet wire, and a new 1mm tip for my iron. I hope this fixes the problem.
thanx for all the help guys
ok, bought some color coated magnet wire, new 1mm soldering tip and rosin core silver bearing solder. Everything was perfectlt soldered when using the new clean tip and the new magnet wire with a really easy insulation melt.