Passenger car lighting with LED strips, EDIT:photos added

[peteski]

Here is a circuit which should work for you.



The part numbers are for SMD components. The bridge rectifier drops about 1.4V, so if your DCC supplies 12V to the rails, the rectified voltage will be 10.6V. That is close to the 9V supply you were doing the tests with. The input voltage in this circuits are not critical. Few volts each way will not drastically affect the LED brightness (or do any damage).

The R1 limits the current charging C1 (so it doesn't overload the bridge rectifier or if you have many cars on the track, so the initial inrush current doesn't trip the DCC booster's circuit breaker). It adds an insignificant voltage drop while the circuit is operating.

The C1. A 100 micro Farad cap should be quite sufficient to eliminate flicker on DCC power with Kato's all-wheel pickup. If not, try larger cap values. Larger tantalum caps are expensive - just use multiple 100 uF caps hooked in parallel. I chose a tantalum cap over electrolytic (which is cheaper) because tantalum caps are smaller and their shape is easier to work with (trying to hide it in the model).  But if you have room, use electrolytic caps.

R2 is the 15K ohm resistor you said worked for you with a 9-LED strip.  You can further experiment with that resistor's value if you want to fine-tune the LED brightness.

The bridge rectifier was chosen for its small physical dimensions (I use it in my designs).  Its ratings are safe for this circuit.

Have fun!  Let us know how it works out for you.

[craigolio1]

Thanks Peteski!  You are the man.

Craig

[Lemosteam]

Here is a circuit which should work for you.

Peteski, have you published a book of these yet?

[peteski]

Peteski, have you published a book of these yet?

No, just this Railwire exclusive. 
I designed a similar circuit, for one of the guys back on the A-board, to convert the standard Kato LED lighting units to be flicker-free.

[craigolio1]

Hey Peteski,

I ordered all of my parts.  All told I ordered enough to do 20 cars at a cost of  $1.80 per car!  With the LEDs at $6 for 5m that works out to about $1.90 per car.  I'm very excited about this....    except that now I should build interiors for my dinner train, which only ran at night and will look lame with out people. 

Thanks again!

Craig

[peteski]

You're welcome Craig.
I normally etch my own printed circuit boards for circuits like that. I hope that the parts I selected for you are large enough for building the circuit without a printed circuit board.

[craigolio1]

Going with SMD components was going to be an issue when it came to holding everything in place.  I didn't want to make a board so what I did was opt for 1/8 watt resistors.  I can solder the rectifier and C1 right to it's leads on either side of the resistor.  Another scrap lead will be used to go from the rectifier to the other side of C1. R2 will be stacked on there as well and perhaps bent around the assembly.  It will make for a flat, compact little self contained rectangle that I can make in bunches and just epoxy to the roof with leads extending to the LEDs and pick ups.  I think it will work just fine.

I'll post some photos when everything arrives and I can assemble a few.

Craig

[peteski]

Sounds like you have it all figured out.  Yeah, post some photos of the assembled unit and let us all know how it works.

[CodyO]

As for the people the cheap from china eBay lots work

I simply amputated there legs and glue them to the seats in the kato cars
You can notice there lack of detail when the train is rolling by

[peteski]

As for the people the cheap from china eBay lots work

I simply amputated there legs and glue them to the seats in the kato cars
You can notice there lack of detail when the train is rolling by

That is a standard thing in N scale. Even Preiser (maker of the top of the line figures) sells very expensive sitting people designed for placement in passenger cars with .... their legs already amputated.   But they still cost as much as the compete figures Preiser sells. 

[craigolio1]

Hey Peteski,

The parts came in the mail today, and i have some questions about orientation.  On the rectifier, there is one leg that is wider than the other three.  This is pin one.  Do I connect the AC source to pins 1 & 3, and the dc output become pins 2 & 4?  Based on the pin out diagram, and how i would wire 4 diodes together to create a rectifier, this looks to be how it would work.  If this is the case, which tab becomes the positive output?

http://www.infineon.com/dgdl/bgx50aseries.pdf?folderId=db3a30431400ef6801141cc1c4cd04e8&fileId=db3a30431400ef6801141cc423c404e9

Also on the capacitor, there is a line on the left side.  Is this the positive terminal?

Thanks, Craig

[craigolio1]

Looking at you circuit diagram and the data sheet for the rectifier, I think i figured the rectifier out.

Pins 2 & 3 are AC in, pin 1 is poss and pin 3 is neg?

Craig

[peteski]

The larger pin (1) is the positive output "+"'  The pin diagonally across from pin 1 is the negative output "-". That is pin 3.  The other pins (2 and 4) are the AC input.

[peteski]

Also make sure to properly install the tantalum caps (as they are polarized). The marked lead is positive. This is opposite from the electrolytic caps where the negative leads are marked.  Isn't this fun? 

[craigolio1]

Great, thanks!