|View single post by CMmodeler|
|Posted: Tue May 10th, 2011 05:29 pm||
I am a new member and this is my first posting.
As far a power supplies are concerned, I do not recommend wall-wart transformers. The output voltage can go very high if lightly loaded. I was using a 12v wall-wart to power a circuit with 17 volt tolerant IC's and blew the IC's because the voltage went over 20 volts. I also do not recommend old train transformers. They are a very unstable power source.
Computer power supplies work well. They are also readily available and cheap. One word of caution - computer power supplies are capable of high currents - fuse the outputs. At the Greeley Freight Station Museum (http://www.gfsm.org), we use 17 or 18 computer power supplies on the 5500 sq. ft., HO scale Oregon, California & Eastern Railroad. Each computer power supply has a line that has to be tied to ground in order to turn the supply on. The +5v supply also needs a minimum load or the supply will shut down. We have found that some computer power supplies (Compaq) are very sensitive to load changes. To counter this, we put a 50 ohm 10watt resistor from +12v to ground as well as a 250uf capacitor in parallel.
As far as building lighting, the biggest problem with incandescent lighting is the heat. A .3amp, 12volt bulb dissipates 3.6 watts of heat. Most of our buildings are plastic and will have multiple lights per building. I prefer LEDs. Warm white LEDs have a yellow tint to them. Avoid cool white LEDs - they have a blue tint. A typical LED only requires .015amps and dissipates less than .05 watts. 10 LEDs produce less heat that one bulb even at 1/2 voltage.
I am currently working on a building lighting system that will cycle lights on and off. It also can dim lights or blink lights. More on that later.
Last edited on Tue May 10th, 2011 05:29 pm by CMmodeler
Yes, I do still play with trains.