I have tried out the Märklin 73400 interior lighting kits and as I show at
http://layout.mixmox.com/1/marklin-73400
there is room for a capacitor.

Has anyone added a capacitor ?
If so, what size and what were the results?
If not, can anyone suggest a suitable size and any caveats?

The circuit can be pretty much be deduced from the pictures.

Hi Dale,

Thanks for pointing out the C1 pads. At least they are there if needed. I intend to power my 73400 from the loc slider so hopefully there will be steady power and I won't need a capacitor. But still an interesting observation and I'm also curious to know what size would be used if needed.

I also recently got a 73400 to check out since its not listed to fit in a thunder box (but it will if you squeeze it in at an angle, ha ha). I did not notice any flickering while testing, unlike some older stuff I have that will flicker just sitting on the track, namely a 4103 thunder box with tail lights and a 3793 BR 52. So I'm pleased with the 73400 so far...

Thanks for the report, Dale.

I think I will stick to 28 Volt bulbs or lower voltage bulbs (610080 or 610040) connected in series in my older era coaches, as I am very found of the yellow warm glow.
In daylight it should not be visible from the outside of the coach, without looking directly at the light source (or dark sucking device).

Thanks for the report Dale. I've just received 3 of these kits, and intend to use them in my ICE 2 train, after I set up some connectors on the coach couplings to give continuous current down the length of the train.

I was wondering how the supports for the lights were fitted, and your picture helped clear that one up - quite simple really!! [:I][:I]

As for capacitors, well I'm no expert, but I would guess a fairly small value would suffice. Don't know if it should be an electrolytic or an ordinary greencap.

I intended running the lights off the loco's slider, as the decoder in the loco doesn't have a spare function output. If I every get around to replacing the decoder, I'll run the lights of a secondary function output.

The train is one of the versions out of a starter set, hence the reason why it doesn't already have lights.

Hi Dale,

very interesting pics of the 73400 lighting set. I agree, there is some space intended for a (not too big) capacitor. IMHO 50 micro farads should be o.k. (e.g. 47 uF/40 V) and prevent flickering. Precise value shouldn't matter (22 or 68 uF will certainly work, too).

But even more impressing to me are the other electronic parts: two transistors, two resistors, and a protection diode. It seems that this could be a current circuit stabilizing circuit which keeps brightness constant at changing supply voltage.

Hans Martin

Chris, capacitance is measured in 'farads'. 1 Farad (1f) is very very very large. 1 pico farad (1pf) is very very small - a pico, if memory serves correctly is 1/1000,000,000.

Mostly capacitors are measured in micro farads (uf). For example, the capacitors in a 12v DC power supply will be around 470uf. There are many types of capacitors as well - there are polarised (they have to be inserted the correct way around), there are greencaps, there are ceramic (the ones you see on the Marklin motor covers are ceramic), just to name a few.

I would guess, for this application, maybe around 47uf would be OK. Not sure if a polarised one is needed or whether a greencap would do. I suppose you can try and see - they only cost a few cents each.

Keep in mind the size of the cap when you go to install. Most likely you will want an electrolytic. Polarized ones tend to be smaller than non-polar. You will need to find one that is rated above the voltage that is running across your rails! This is most important! If the capacitor cannot handle the voltage, it will either fail prematurely, or immediately, and in a most spectacular fashion! Make sure if using polarized that you observe correct polarity (read back to the "spectacular failure" section previously). An electrolytic cap installed backwards is effectively a short circuit.

I haven't tried it yet, but my first choice would be a 10uF, 35V cap, as most of these tend to be small, can hold a decent, short-term charge, they are generally CHEAP, and easy to find. I would be hesitant to use a cap much larger than that without knowing what kind of inrush current the circuit/rectifier/power supply can handle.

If you are more patient than I (and I work on electronics for a living), you can get "surface mount" caps and try installing those, since that is the type the board is made for. If your eyesight is failing, or if you have shaky hands, or the patience of a typical 2-year-old 3 days before Christmas, go with the "normal" kind with wire leads. I would suggest, given the space available, to use a radial, as opposed to an axial cap. Polarity isn't marked, but from the photos posted above, it is easy to figure out. Match the negative ( - ) terminal of the cap to the negative ( - ) terminal of the rectifier. On most electrolytics, the positive terminal is not marked, other than having a longer lead than the negative lead.

Hope this helps,

Don

I have the following problem: the wheels of the cars which I equiped with pick up shoes for lighing, are derailing on the turouts, even I was adding some extra weight on the cars. How do you handle this?
Did anyone lighted the ICE 2 cars. What pick up shoes are suitable for ICE 2?
Thank you,
Adrian

Hi Mike. I put a piece of tape over the pin/socket or some tape to hold the wire in place before it reaches the pin/socket.

David

Gautham, have you considered locking connectors like those from here:

http://www.action-electronics.com/molex.htm#Mini

Try the two-pin locking one: WMF-3901PRT. You can use the spare pin to pass the gound wire too.