# Help wiring capacitor for lighting passenger cars



## Artieiii

I have 3 Walthers NJ transit passenger cars. I would like to add LED lights with a capacitor to avoid flickering. I am using DCC. I made track pickups. I bought a diode bridge and a 330uF capacitor. I wired the AC leads on the bridge to the track pickups and the positive and negative leads on the bridge to the capacitor. Then i wired an led with resistor in parallel to the capacitor. As the capacitor charges, it sends DC current back to the tracks and my NCE power cab resets. What am I doing wrong? TIA.
-Art


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## gc53dfgc

you are adding more charge to the system then it can handle causing a short. you need LEDs of a low voltage and use a resistor for them. I think that works but the second you take the car off the rails it turns off so then you need a capacitor of lower or equivalent voltage to what is by the system I think the proper thing is not a capacitor but some other thing that only stores power. Another way is to have it so it goes tack-bridge-resistor-capacitor-resistor-bridge-track. I belive that will if you get the right resistors change the 14-18v standard of the system down to only a few volts then the capacitor charges up and releases through the lighting system then the other resistor will lower it back to the 2-8v and keep the system from shorting. You may need a resistor-capacitor-resistor for the LED to not blow depending on the capacitor. Make sure you test this off of a car first to make sure it all works properly as some playing around will be required.


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## NIMT

If your running DCC you shouldn't need anything other than LED's and resistors, one for each LED. No capacitor or bridge rectifier needed! 
Use an old Decoder and then you can control the LED's too!
Take an LED and Resistor and touch it to the Rails do you get flicker?
If your getting flicker in the cars then your pickups or wheels are dirty.


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## gc53dfgc

Well now if you are using a decoder thats different but I figured he wanted a non DCC decoder controlled car with a similar thing to what overland models and ligar technologies offers with thei lighting packages where they stay on for about 30 seconds even after the car is lifted from the rails so if you go through a dirty part of rail you don't get any flickering lights at all.


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## NIMT

GC, If what Art wants is to have the the cars stay lit threw dirty track, It's not electronics he needs it's a track cleaning car!:laugh::laugh::laugh:


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## Artieiii

Sean,
The problem is that each car has only 4 wheels for each pole. These cars were not designed for track pickups and nobody makes replacement trucks for these cars. The pickups I made are not great so even with perfectly clean track, they will flicker. By using a capacitor, I should be able to pick up enough power to get the capacitor to charge so that even if the pickups aren't perfect I should get flicker free lighting. My MTH SP daylight cars are equipped with capacitors and they work great (of course they have excellent track pickups).
-Art


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## gunrunnerjohn

You will probably need to put some resistance between the cap and the track pickup to avoid screwing up the DCC system.


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## Artieiii

gunrunnerjohn said:


> You will probably need to put some resistance between the cap and the track pickup to avoid screwing up the DCC system.


Ok Gunrunner,
I will try that. I was messing with a 1000uF cap and that was much worse. I think I may be able to get away with a 330uF cap for my cars. I had last nite to decide what to try next. My plan is to run the track leads with alligator clips to my setup to eliminate the pickup issues first and see how that works before proceeding to the next step. If I am successful with that then I can rework the track pickups. With the smaller cap I may need to run more than 1 led to draw more power from the cap. I am really enjoying this electrical stuff.
-Art


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## NIMT

Art,
I see (hear) what your trying to do now! You want a charging circuit with the "battery" being the capacitor. I have a ton of electronic parts and I should be able to work on this later today. Between all of us we can figure it out! Can you get a picture of the circuit board in the other car as a reference?


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## tankist

Artieiii said:


> As the capacitor charges, it sends DC current back to the tracks and


no it doesn't. - it can *not * (edit )discharge via the bridge. i built same to power indication leds from track power - worked fine. check your wiring, polarity, etc.




can't say if this is the culprit, but what bridge do you have? DCC is higher frequency, the ordinary 1N4001 diode is not capable of switching on and off as fast. as far as i know Schottky diodes needed here. these have very high switching speed and very low forward voltage drop (also lower reverse voltage but in our application it is non issue).
reardless thats what i use for my rectifier bridge


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## NIMT

Thanks Anton
You are the electronics guru! I have not worked on this kind of problem before, but I should, I have 40+ passanger cars to light up one of these days, But then again I think I'll go with a decoder in them to get better lighting control!


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## Artieiii

If I figure this out, I think I may put a FRED on the last car. Radio shack sells a blinking red LED but that might be too big. I got this idea for lighting with capacitors from looking at the Ring Engineering EOT device. Plus I just got a shipment of 50 LED's to play with LOL 
-Art


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## Artieiii

Anton,
Here is what I used:
This is the Bridge Rectifier:
http://www.radioshack.com/product/index.jsp?productId=2062581

Here is the Cap I used:
http://www.radioshack.com/product/index.jsp?productId=2103623

I am not using a circuit board I just soldered the connections as a test run. When I get it right I can streamline it on a circuit board.

I have another question:
What gauge wire is used in DCC controller chips?
Radio Shack only has 24gu speaker wire but it is too stiff and the insulation is really thick for my purposes. I need to order some fine gauge wire online.
-Art


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## tankist

i haven't found schottky bridge rectifiers so i composed one myself out of discrete sch diodes. but i don't think its your problem. any chance to see a picture of your circuitry? i'd check that for mistakes first. with all the leads it is very easy to miss-wire (well at least for my clumsiness,). i would advise you to get protoboard / breadboard for developing your circuits. dirt cheap on ebay










why are you guys always rushing to give away your money? take a old printer cable or s soft network cable (stranded) and open that up. yours free. #24 to much? use wire from old headphones or that el-cheapo good for nothing cellphone mic bundled with your latest cell. still not thin enough? unwind some old miniature transformators or speaker windings. or from any suitable old piece of elecrtonics ,tons of it are being given away for free on craiglist for example) and un-solder the parts from there. they always have capacitors there.
and bunchh of other goodies.



PS, i love printers! steppers, belts, gears anda lot of usable hardware. the bigger dot matrix are a winners, HUGE powerfull steppers are inside to drive those hefty matrix heads fast. VCRs are good too. some good stuff can be got out of old CD and DVDrom drivess. slim DVD players make awesome project enclosures. i can go on  




NIMT said:


> Thanks Anton
> You are the electronics guru!


i know a thing or two, but im very far from being proficient at it. let a lone guru.


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## Artieiii

Anton,
Here is a wiring diagram for the circuit I am working on. It seems ok with the 300uF Capacitor but not the 1000uF Cap. I will try to put alligator clips on the track to eliminate bad contacts first and see how that goes.








Not sure if my wiring symbols are correct.


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## Artieiii

Update, I used the alligator clips to the track and wired a 1000uF cap waited about a min the the Cap exploded (was hoping to hold a charge a bit longer). Now I rewired it the same way with a 300uF cap and several minutes have passed. No problems, so far so good. The cap holds a charge for a few seconds with no track power then fades away. Not sure how 3 or 4 LED's in parallel will work yet. Still experimenting. If this keeps working I should have my cars electrified pretty quickly. Now I have to work out a good way to get power from the wheels to my experimental setup. I was nervous about running an engine with the lights hooked up so I used my crapiest engine and it's working fine.
-Art


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## gunrunnerjohn

If you wire a cap directly to the track without the bridge rectifier, it'll blow when you reverse the polarity of the connection!

If you want better results, see my modification of your wiring diagram.


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## Artieiii

gunrunner,
please explain why you suggest this modification? I need to know WHY? Its just the way I am.  I wired my setup like my diagram and it works perfect. Even with 3 LED's wired in parallel. If I add the extra resistor will that help the LED to glow longer on the charge of the cap? I could use the extra resistance in the circuit anyway to make the LED's just a little dimmer.
-Art


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## gunrunnerjohn

OK. I'm simply isolating the capacitor and bridge from the track so you won't have DCC issues with attenuation caused by those components. I split the resistance because the higher the voltage is on the cap, the longer it'll run the lights for momentary power glitches. I figure the 100 ohms is probably sufficient not to cause issues with the DCC.


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## Artieiii

Gunrunner, 
I took your suggestion and added a resistor. I got a circuit board and the rest of the stuff to do my other 2 passenger cars. Here is a shot of my completed circuit board. The red wires are for track power, the white is positive DC and the black is negative DC. It will fit nicely on the floor of my cars. I also made a false ceiling out of cardboard and wired 3 LED's for the roof lighting. Then I got another blinking red LED from radio shack and made a FRED. It should be completed sometime this evening.
-Art


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## NIMT

Art,
So how long does this circuit power the LED's for when it losses track power?


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## gunrunnerjohn

Probably not long without a larger capacitor.


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## Artieiii

NIMT said:


> Art,
> So how long does this circuit power the LED's for when it losses track power?


just a couple of seconds then they run really dim for about 15 more seconds.
-Art


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## NIMT

Thats cool, Sounds like it should work for you!


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## gunrunnerjohn

A couple of seconds is plenty for most situations.


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## Artieiii

*Finished!*

Ok after many hours of messing around with it, 2 of my 3 Walthers Horizon Fleet Commuter Coach NJ Transit cars are done. The FRED is sweet! I figured out that the blinking red LED for the FRED requires DC current to blink, so the circuit board with bridge rectifier was essential. It appears that my track pickups were the issue with my problems. This time i took some sandpaper to the axles to get the crap off them. Thanks for help everyone. When I get the 3rd one done, I'll post a video.
-Art


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## gunrunnerjohn

Sounds great, glad it's all working out.


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## Artieiii

*Video Attached*

Here is my Bachmann Spectrum F40PH with blinking strobes and my Walther's NJ Transit passenger cars with homemade LED lighting. The lights appear way to bright in the video but they are no where near that bright in real life. My 2 scratch built bridges are also in the video. I think I like the FRED the best. The blinking FRED in the last car uses more power than the other LED's so the LED's in the last car may need smaller resistors.
Comments? Suggestions?
-Art
http://www.youtube.com/watch?v=4jRuxaoJ8G0


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## gunrunnerjohn

Looking good, and think of all the soldering experience you've accumulated recently.


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## Artieiii

Yes Gunrunner, I had 2 buy2 new soldering iron tips. I never had to buy one of those before.
-Art


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## gunrunnerjohn

It's like riding a bike, once you've done it, it comes right back.


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## Artieiii

gunrunnerjohn said:


> It's like riding a bike, once you've done it, it comes right back.


Haha....I went out to my shed the other day and rediscovered my old unicycle so I pumped up the tire and took it for a spin. It's just like riding a bike!
-Art


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## gunrunnerjohn

Well, I've only personally known one guy that could ride a unicycle, and when I tried, it wasn't pretty!


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## Artieiii

gunrunnerjohn said:


> Well, I've only personally known one guy that could ride a unicycle, and when I tried, it wasn't pretty!


Gunrunner,
Now you know 2 LOL. It's not something you can just get on and ride. It took me about 2 days of practice before I could ride it.
-Art


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