Hi alloboard,
First we need to know what sort of lighting you are using. 12 bulps, 1.5volt bulbs or leds and if you are DC or DCC control.
As a guide,the capacitor should be wired in parallel with the light bulbs or LEDs. The capacitor needs to be a high value 200 micro farad or more.
These are usually electrolytic capacitors which unfortunately are polarity sensitive. Meaning that they only work when they are connected to a DC supply that doesn't change polarity. (they pump out their innards if connected the wrong way around for too long)
So you may need a bridge rectifier to keep the voltage across the bulbs the same polarity no matter which track polarity you have.
Also electrolytic capacitors have a max voltage rating, you should ensure that the peak voltage that the capacitor receives from the rectifier is lower than the capacitors voltage rating. (I use 25Volt min on 12 V DC system)
and one more thing, a large value electrolytic capacitor looks like a short circuit until it is charged up, so you need a resistor between the bridge rectifier and the capacitor/lights to prevent your controller's short circuit detector from tripping out. As for the value of the resistor, I use the SIAS system to determine, but start at about 100 ohms
I wish it was easier than that but it's not.
Cheers
(SIAS = "Suck it and see" commonly known as trial and error)
Alan Jones in Sunny Queensland (Oz)
I use basically the same set-up in my cabooses. I use DCC, so a bridge rectifier was required. I found some computer memory caps work great as you can find much higher capacities in smaller packages than standard caps.
Another variable is that I use high brightness LEDs for interior illumination. I installed a 100 ohm resistor on the input lead before the capacitor to limit the current inrush and installed a 470 ohm resistor on the output lead from the capacitor to the LEDs. This 470 ohm resistor does two things .... first, it limits the current required for the LEDs to operate properly and second, it creates a slower drain on the capacitor. This slower drain allows the LEDs to remain illuminated when removed from the rails for a full minute before they begin to dim and go out .... more than ample time to eliminate any flickering !!!
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
Here is a link to a bunch of DCC lighting info.
http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm
http://www.mrwithdcc.com/
http://www.awrr.com/lighting.html
If not enough info, do a Google search for DCC passenger car lighting.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
alloboard wrote:How do you wire a capacitor into the coach lighting wires? Where again do they sell capacitors? Hopefully RadioShack might sell capacitors.
Radio Shack does indeed sell capacitors, and bridge rectifiers. However, you might want to investigate if the manufacturer of your particular passenger cars, or the Walthers Catalog, have lighting kits for your specific cars.
An alternative to capacitors for flicker-free lighting is to run the lights off of batteries like Rapido does in their cars. But this requires that you have a way to turn them on and off easily without taking the cars off of the rails.
I was just re-reading the May 2008 MR and on page 48 is all the info you need. Just be aware that there is an addendum in the July issue to correct one of the diagrams.
I notice that it doesn't use the 100ohm resistor on the input side but he is only using one LED per circuit and 3mA current is enough to light his LED so he uses a 4.7K resistor. cheers
Mouser Electronics. http://mouser.com/
They have pretty much any electrical component you can think of, and many you didn't even know exsisted!
Cheap prices too.
Rotor
Jake: How often does the train go by? Elwood: So often you won't even notice ...
This article should give you the information you need:
LED Lighting
dave
I appreciate all of your inputs.
davidmbedard.....6 years to say "thank you".....lol. David B
Alton Junction