My N scale layout is going very very well, and I am personally very impressed. My mountain has turned out to be most impressive, and as a newbie, it’s amazing to see the reaction with family and friends with the results being so realistic. I really appreciate all the help from this forum, the local train retailers, and the technical support from Woodland Scenics.
Okay, for my question. My N scale layout has approximately 44 lights. These lights are a combination of of Building Lights, Street Lamp Posts, and Lighted Billboards. I quickly learned that with so many lights I overloaded my high end Power Pack, (with the lights on AC and the train running simultaneously), therefore, with the help of Modelers in the business, I seperated my AC lights with a separate AC Power Supply.
My AC Power Supply is a 12 VAC 3.3 AMPS. Will 3.3 AMPS be able to handle this much current or load? So far my lights are running fine, but I’ve only have 38 installed, with another 6 lights to go. I tried to find a 12 Volt AC Power Supplier on the Internet that is 4 or 5 AMPS, but many vendors don’t call out their AMPS on their actual package or description.
Also, what is the life expectancy of these lamps? Do the bulbs ever burn out?
The vendor for all of these Lights are from Model Power. I am not sure what the MA is on each Light, because they don’t say on the package. Can you help?
You can probably add as many lights as you like. Just put a 3A fuse in the circuit so you do not over heat things.
LION uses ONLY LEDs. and has hundreds of the things on his layout. Before I am finished there may be thousands of them on the layout. I should be able to light the room without turning on the room lights. Indeed, I just bought another 180 clear LEDs at Walmart for only $22.00! They sell Christmas lights, I keep the lamps and throw away every thing else. A 1KΩ resistor in series with the circuit and it is done.
But what the heck… If you are worried about it, add another transformer and have two circuits.
The site that sells the “lamps” should specify their ranges of voltage, type of current, and maximum amperage draw. In any event, it is simply a matter of adding up their current demands as you add the lamps to the draw. Simple arithmetic.
That said, many of us drive these tiny bulbs with too much voltage. Why they may look nice 'n bright, they are also running very hot, and they burn out quickly. They are probably best run near the 75%-80% range for the maximum ratings.
There are on-line suppliers, and local electronics supplies stores, that can help you get a suitable power supply. Just have a good handle ahead of time what your actual needs will be. Let them quote you a price once they do the searching.
Sometimes electrical shops have stuff lying around. I found a good power supply for my Walthers 90’ turntable by calling a local electrical shop. He just happened to have what I needed. He tested it for me to ensure it met specs for the turntable, and sold it to me for a song.
I use mostly Miniatronics bulbs. These are rated at 30 milliamps. If your bulbs are similar, then you should expect to need 0.030 x 44 = 1.32 amps, well below the rating of your supply.
I’ve been buying my supplies from All Electronics, www.allelectronics.com. They have 12 volt supplies in the 4 and 5 amp range.
And now for the warnings: Most of these supplies do NOT have circuit breakers. Instead, they have 1-time internal fuses. If they go, you’ve got another paperweight. So, follow the Lion and put a fuse into the circuit.
Bulbs will burn out. However, Crandell’s suggestion about running the bulbs below their rated voltage is a good one. I use all 16-volt bulbs and I run them at 12 volts. Instead of glaring light, I get a soft, warm glow that looks much better to me, and preserves bulb life, too.
As the years pass, you will add more lights. Your layout will get bigger, or you’ll decide to add a few more street lights to highlight a scene, or you’ll start putting lights and interiors in your buildings. Slowly, you’ll creep up to the limit of the power supply and then…poof. This will happen. I hope the poof is a fuse and not the supply.
My personal preference is to use multiple separate power supplies, and (in the case of building interior lights) several switched circuits on each. That way when Joe Shopkeeper goes home, his shop goes dark and his house lights go on. (Joe lives in an apartment above his shop.) Then his house goes dark, while the streetlight and the security light at his back door stay lit. The latter are off during daylight hours, but the shop interior is well illuminated…
In part, this is driven by the fact that my yard sale addicted sister has gifted me with a number of otherwise useless toy train power packs. I have also scored a number of inexpensive filament transformers - 12.6VAC center tapped, rated 3 amps but capable of powering 6 amps worth of 6.3VAC circuits. The toys are rated a lot lower, but are only used to light up a few scattered rural buildings each.
I second Mr Beasley’s motion on running lamps at less-than-rated voltage. For residential purposes, my 2.5 volt lamps are set up in series strings of four, which gives about 1.6 volts and a nice yellow glow typical of my prototype’s nighttime appearance. Commercial and rail structure lighting uses 3 lamp strings and yields 2.1 volts per lamp and a whiter light. (I bought a couple of cases of Christmas microlamps for about [2c] per lamp, with sockets, and I don’t see any advantage to wasting power warming resistors - it’s already hot enough here!)
One thing I do, since my circuitry is somewhat complex, is to document EVERYTHING. Schematics of every circuit, with notes on where to look for the various components and exactly what they are. That way, if Joe’s two house lights DON’T come on, I know that they’re in series with one in another house down the block and one in a private room of the restaurant around the corner. Lift the roof, quick bulb swap - if that doesn’t work, swap the next bulb. They pull out and push in.
These lights would have to draw over 70ma each to overload your power supply. More typical ratings for bulbs small enough for N scale are 30 to 50 ma, so you should have no problem with the 3.3 amp power supply.
I always set up multiple circuits - so instead of one switch turning all the lights on and off, there are multiple switches, each with a subset of the lights attached - for example, it owuld eb common for allt he street lights to go on at the same time, but businesses and homes would be on different schedules. You don;t need multiple power supplies for this, just multiple switches. Something like the Atlas Connector works well, each one is three DPST switches witht he internals all wired - plus you can attach more to the first one if you need more than 3 circuits. On one side, you connect your two wires fromt he power supply, on the top are sets of 2 terminals that go to the lights being controlled by that switch. If you’re more towards the clueless side when it comes to electricity, these make it easy, at the penalty of costing more than a bunch of simple toggle switches (plus they are large rectangles, and take up more space on the control panel than simple toggles).
Running bulbs below their rated voltage is highly recommended. At full voltage they will often be way too bright, and glow through places they shouldn’t. Run a 12V bulb at around 9V and it will have a pleasing glow - plus last many times longer than it would running at the rated 12V. An easy trick for dropping voltage with a DC supply is to insert some diodes in series with one power supply lead. Each diode will introduct a .6 to .7 volt drop that won’t vary depending on how many lights you switch on at a time like a resistor will. Nor will they get hot. 3 or 4 diodes like this: http://www.radioshack.com/product/index.jsp?productId=2062591&filterName=Brand&filterV