Fairly standard install

Except for the size.

DCC uses a "hot common", so the blue wire (positive common) goes to the LED's anode.  Most people put resistors on the switched (negative) side, so that connects to the cathode.

I use 1500 ohm resistors on most of my installs.

Scott Chatfield

Which way?

Providing you are including the current-limiting resistor (which can go in either leg), it doesn't hurt the LED to connect it either way round. One way it will light, the other way it won't. So you can try one way and if it doesn't work, try the other way. That's obviously useful in cases where you don't know which leg is the anode and which is the cathode.

This may help ...

I tend to breadboard things and make notes before committing everything with solder and shrinkwrap.

Problem with LEDs is they are diodes and only pass current in one direction.

This might help:

@ JeffRA

That is the way i double check when I'm doing installations.  I use a battery with proper resistance for power and put the leads on an unidentified LED if it doesn't light I change the test wires. if it still doesn't light i replace the LED.  So the answer is that it makes no difference which way the polarity is as long as the battery has the correct resistance,  Scott suggested 1500 ohms or 1.5K which is very good.  Between 1K and 3K or 1000 ohms and 3000 ohms should be a good range on a 9 volt battery or a 12 to 16 volt output if you don't have a 1.5K.

@amsnick Decoder Buddy has onboard resistors?

Installing decoder and LED's

I can  always count on great advise from my fellow modelers. Should i assume that the voltage coming out of the decoder at the headlight leads is the same as the decoder picks up from the rail?  The electrical side of the hobby is not really  my  long suit - Im just trying to understand what Im doing.

Also, the LEDS are on enameled wire.  How do i get the enamel off the wire to make the electrical connection.

Thank again for all  your help

Joseph

More tips

Joe, I don't think a LokSound Mini will work with a Decoder Buddy.  Amd a Decoder Buddy will not fit in a Bachmann tank loco.  Correct me if I'm wrong.

Joseph, the output voltage on the function leads depends on the decoder design.  Some have current limiters that allow 15 milliamp bulbs and LEDs to be connected directly without resistors.  You have to read your decoder's specs to know for sure.  Most hardwire decoders do not have current limiters and put about 1.5 volts less than track voltage on the function leads.  So if track voltage is 15 volts your bulbs will see 13.5 volts.  Total amperage available for functions is often 500 milliamps.

The easiest way to remove varnish from magnet wire (which is what you have on those LEDs) is to run the wire through hot solder.

Scott Chatfield

Or a match, or

even scraping with a pen knife.  Some enamels are quite resistant to soldering temperatures, but will give up eventually.  A classmate of mine just used the lit end of his cigarette.  Better to use a match, cigarette lighter, or a candle.

Blair

Hi Joe.

Yes.  Exactly right about the resistors in the Decoder Buddy! 

When I don't have track power I will test the LEDs directly with the "battery + resistor" combination.  I'll even connect the red Positive "battery + resistor" lead to the U+ side of the small connector board to make sure of the Aux + LED matchup and ascertain that the combination is working correctly before I proceed. 

My belt and suspenders show here I guess...  Thanks!

If I can ask here real quick...

 Sound being a given, what's the big advantage of the 21 pin decoders? Lot's of lighting functions?

Yep

Yep, lots of functions for lighting or whatever. 8-pin is limited to just front and rear headlight, everything else is hard wired, including the speaker.

Fully utilized a 21-pin has pins for the speakers and allows up to a dozen functions, all plug enabled if you use a Decoder Buddy. You wire the LED leads to the plug in Decoder Buddy function socket, plug in the 21-pin decoder and you’re off to the races. The Decoder Buddy already has LED resistors on the board.

Hard wired means you can only remove the shell completely from the chassis by using wire snips. It also generally means wiring in your own resistors.

Hi Michael,

Lighting is one advantage.  It is the one that got me started.  The upgrade and change is another.  Pull the old version and sell it and add a new version or another manufacturer’s decoder  There are a few diehard camps and selling a brand x decoder in a locomotive to brand y enthusiast is a lot easier with a spot that will hold each or all brands.  The 21 pin decoder also has provisions for addition of a stay alives.  Please excuse the shameless plug...  The Decoder Buddy makes this very easier still.  If one is converting a locomotive the advantages also include a removable lighting board for all the new LED lighting that can be installed in the shell and pads for two and three wire stay alives.  Generally a good, small investment for ease of installation, shell separation and versatility of decoder manufacturer’s decoders and sale of the locomotive when appropriate.  The footprint of a 21-pin decoder is relatively small and when fitted to a Decoder Buddy or an even smaller Decoder Buddy Mini, installations in tight areas are benefited too.  This is true also when adding a speaker and or stay alives in tight quarters.

Hope this helps.  Thanks for asking!

Decoder Buddy Tiny

I hope I’m not hijacking here but if you were doing basic LED lighting (forward and rear only), can you solder the LED wires to the AoF and AoR on the Tiny?

RS.

Be a little careful of the Decoder Buddy Tiny.  It does not have resistors and says Tiny on the board.  It was intended for small steam and diesel switchers with light bulbs.  People came back and wanted it with resistors so they were added and it was renamed the “Mini”. The Mini generally has 1K resistors.  It can be special ordered with “0” ohm resistors which essentially makes it a Tiny with no resistors. The “0” ohm resistors have a 0 on them. 

 

This is a Mini with 2.2K resistors in the red circles.  The Tiny will most likely not have any resistors present.  If you are using a Tiny you must choose resistors for bulbs (not recommended) or LEDs.  Separate 2.2K axial resistors are also provided with the Tiny and the “0” ohm Mini.

The answer is YES, IF you see resistors on the board and they do not a “0” printed on the resistor.  Let me know if you have a Tiny and want a Mini with resistors onboard for your LEDs, please.

I hope this helps.

MINI with Resistors

Thanks Nick! I do have a Mini and the resistors say 01B on them. I purchased the board with 1K resistors. If the answer is still yes, would the red wires go to the A0 functions and black to the U+(ground)?

Got it!

Red goes to U+ and Black go to the As.  Don’t use A6 or A10.  These two are for three wire stay alive control wires.

You should be good to go now!  Enjoy!