If you need a cooling fan for your railroad project, might I suggest you check these out.
Antec temperature controlled fans.
http://www.antec.com/product.php?id=1259&pid=142&lan=ecThey have a built-in temperature sensor that adjusts the fan speed. The warmer the air, the faster the fan runs. They run on 12V DC.
I used these when building computers to keep the fan noise as low as possible. Some of these fans have been running 24/7 for 5-6 years. They come in different sizes.
Dean
