I have a lot of LEDs on my layout. Generally, I wire them with resistors separately.
However, on some of my scratchbuilt buildings, I will solder one resistor for several of the interior lights. It's just a lot easier and takes up a lot less room, and it doesn't affect the light output.
I probably wouldn't put more than several lights on one run. Like Mel, separate lines make everything a little easier if you want to change something or there is a problem.
York1 John
John-NYBW I have a related question. Until recently I have used incandescent accesory light fixtures attached to a 12 volt bus. Lately I have been installing LED lights but have yet to wire them. They came with the resistors included. Can I connect them all to the same terminal block and then use a single resister connecting the terminal block to the power source or does each light need it's own resistor. As you might have guessed, electronics is not my strong suit.
I have a related question. Until recently I have used incandescent accesory light fixtures attached to a 12 volt bus. Lately I have been installing LED lights but have yet to wire them. They came with the resistors included. Can I connect them all to the same terminal block and then use a single resister connecting the terminal block to the power source or does each light need it's own resistor.
As you might have guessed, electronics is not my strong suit.
You can, but there are good reasons to use a separate resistor for each LED.
LEDs don't always have the same electrical properties, so running them in parallel will not guarantee the same current through each, which could result in differing brightness.
As you increase the number of LEDs strung together in such a parallel structure, you increase the total current draw and may eventually need a higher wattage resistor.
Resistors are cheap.
It takes an iron man to play with a toy iron horse.
I totally agree with not using wall warts!I use a bit different approach to my accessory power. As I use primarily incandescent Grain of Wheat bulbs in my structures and street lighting, 12 volt bulbs operating at 8½ Volts. Incandescent bulbs operating at reduced voltage not only look more realistic and almost never burnout.My approach is to use a 12 volt high current DC power supply for the main accessory power source, in my case as I have a lot of accessories so I use a 12 volt 30 amp power supply. To get the various voltages I use voltage adjustable DC to DC converters. They can be adjusted from 1.2 volts to 12 volts and be purchased from about 1 amp to 12 amp capacity, the 4½ volt and 5 volt DC to DC converters are 3 amp the other two are 12 amp.1) 1.4 volts for 1½ volt micro bulbs, running at 5 amps. (lots of micro bulbs, 98 vehicle headlights)2) 4½ volts for Micro Engineering signs, running at less than 1 amp.3) 5 volts for Arduinos, running at about 1½ amp. (12 Arduinos)4) 8½ volts for 12 volt incandescent bulbs, running at 9 amps approximately 200 bulbs.Total current running off my 12 volt 30 amp power supply is 18 amps with everything turned on, I started out using a 15 amp power supply and over a couple of years I slowly ran out of current. I have 32 toggle switches on my control panel to control the lighting.Lots of accessories on my layout.As for accessory wiring I have always used a home run from each device to my control panel, individual circuit for every accessory, I like the ability of individual control. A lot of wire but for me much easier for trouble shooting should something go wrong. Mel
My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
I am tempted to note that you can likely go a long way toward powering lights if you take your bench-bus conversion off one or more peripheral connectors in an existing computer and design your strings for that voltage. If you are running something like JMRI on an older tower PC you probably have several unused four-pin connectors bundled up on its power supply, easily capable of substantial wattage to run hard drives, tape storage, and other legacy apparatus, and these are essentially 'free for the taking' just by putting a grommeted hole in the case somewhere... this also optimizes any power-supply insulation, casing, and cooling issues.
MisterBeasleyI'm through with wall warts. They are typically too small and eventually overload and burn out if you're not careful about how much amperage you're asking for. Yes, LEDs won't use as much power.
I agree. I might be off base but as I am delving into the world of animation and lighting for the layout it seems to me what makes the most sense is to get a PC power supply and then couple that with an ATX to Benchtop Power supply conversion kit.
This way I have 3.3V, 5V, 12V available for the different power requirments. This might be a more expensive set up but it would be rock solid reliable and there would be no fear of blowing all the electonic gear connected to it.
I've just started research on this so I might be going in the wrong direction but on the face it does seem to solve a host of issues.
charles
I have the usual track power bus running around my layout. I also run a couple of "accessory buses" around as well. I supply these with 12 VDC, not fom a wall-wart but from a real power supply of 4 or 5 amps. Most of my accessory lighting is incandescent, because I prefer the color balance for my era. In some place I run a separate bus for streetlights because I have the Walthers Cornerstone ones where the bulbs are not replaceable and I like to selectively turn those off. I typically run 16 volt bulbs on the 12 volt circuit to prolong bulb life and reduce the brightness of the lights.
I'm through with wall warts. They are typically too small and eventually overload and burn out if you're not careful about how much amperage you're asking for. Yes, LEDs won't use as much power.
When a wall wart goes, it has an internal one-time fuse, so it becomes an ugly useless paperweight. So, I fuse my power supply circuits to protect them, got from the overloads of "illumination creep" and from inadvertent shorts and wiring errors.
wrench567 Hollow core doors are easier to fish wires through if you take a piece of paper and roll it up. Put the rolled up paper through the hole you drill so it protrudes through both sides. Slide the wires through the paper and pull the paper tube out. Also works good on thick foam.
Hollow core doors are easier to fish wires through if you take a piece of paper and roll it up. Put the rolled up paper through the hole you drill so it protrudes through both sides. Slide the wires through the paper and pull the paper tube out. Also works good on thick foam.
I use pieces of styrene tubes to hold the JP lites and feed the wires. For the other ones the underside of the door has some larger holes in it to make sure the wires feed through properly.
You might consider a 12 to 14 volt DC power buss under the layout for scenery lighting using an old wall wort. Regular bulbs will work along with LEDs. Depending on the bulb voltage will determine the resistance needed. LEDs on 12 volt work decent with a 1K resistor or higher. Some of my interior LEDs have a 2.2K resistor for softer lighting. I also have a toggle switch on the scenery buss to turn it on an off.
Pete.
Got yet another one for Forum friends. I have decided to add a bunch more lighting to my layout. One type I have on order but the other I need some help with.
I purchased a total of 20 of this type of street light: http://www.ebay.com/itm/133469640953. I figure that each side of my streets wil get at least 3 lights each. (I have a shorter street that may only get 2 per.) I'm just trying to figure out the best/simplest way to wire them up.
The second question is related to the correct type part. After seeing another railroader's passenger station, I figure that I should light my passenger platforms. The platforms are Atlas' fine HO platforms and are already built and connected. There are two units with one on each side of the station. For longevity and simplicity (only having to do the install once), I figure that some some of LED is probably a good idea. I just don't know what type and colorto get. I'm thinking warm white like the other LEDs I have (Woodland Scenics' Just Plugs). I don't want to try to get more of those as for as many as I would need would get rather expensive. I'm also again not quite sure if I should wire them in series or not. (Less wiring to hide is my thinking for that but my knowledge of resistors for something like that is nonexistant. That portion of the layout is also a hollow core door so fishing wire is a pain as well.)
I figure that all the lighting will probably end up on the AC side as the rest of the lighting is AC as well.
As usual, any assistance that can be provided would be most welcomed.