As I approach the wiring stage of my DC layout, I notice some online references regarding use of a secon d power pack or power supply device to provide electrical service to structure lighting and other secondary uses.
One set of comments says to use those small plug-in wall wart-type transformers, but their default "off" position is to unplug each one.
Another set of comments says to use an inexpensive surplus desktop PC or similar power supply (but what about an on/off switch?).
A third route is to use a second power pack, using just the AC terminals, where there is a built in on/off switch, then run a pair of bus wires for lighting separate from the main track bus wires to connect the structure lighting leads.
I can get an inexpensive additional power pack- but which one, given that I am using LEDs in all structures that draw very little power.
???????
Cedarwoodron
You can't run LED's on AC.
If you use the wall-wart(s), just plug them AND your power supply to the track ALL into a plug strip that has an on-off switch.
You'll then have just one switch to shut down the whole railroad.
Ed
How much power you need depends on how many LEDs you have. An individual LED with the typical 1K resistor draws 9ma. But how many LEDs do you have in each structure, how many structures, how many streelights, etc? If you have a total of 100 LEDs - that's 900ma, .9 amps, and you never want to run the power supply at the maximum rating, so for that much, I'd look for something rated over 1 amp. Or perhaps break things up so the LEDs in one town are powered by one wall wart, and another is used to power the second town - more things to plug in but each one can be lower capacity.
And don't worry about getting one that's too big. 500ma worth of LEDs will draw 500ma, feeding that with a power supply rated for 2 amps won't fry anything.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
When I started wiring my layout, I would go downstairs to my workshop and find the box of wall-warts, and select one that was appropriate. This was fine for a while, but I prefer small incandescents for structure lighting. (The warmer glow fits my era better.) That means more amperage. One of my wall-warts overloaded and woke up dead the next day.
Go online and look up power supplies on eBay or Amazon. For 7 or 8 dollars, you can get a 5 amp, 12 volt DC supply, shipping included, and it will be at your door in less than a week. Go to Radio $hack and get a fuse clip and some 4-amp fuses, too, because these supplies don't have circuit breakers and a short can kill them. I plug all my supplies into outlet strips, so I've only got a couple of switches to flip to bring all my power on my layout up or power it down.
I run accessory power buses beneath my layout. Generally, that means one bus for structure lighting and another for streetlamps. These are controlled by small toggles on control panels, so I can leave the buildings on most of the time, and leave the streetlamps during the day, or leave everything off when I'm just running trains and not worried about "atmosphere."
It takes an iron man to play with a toy iron horse.