mod project help

[kidsony]

i got a couple of questions. i am making a fan bus and i need some help calculating what resistors i need. my first one is
what size resistor will i need to step 12 volts down to 7 for my fan, my second question is what size resistor will i need to step 12 volts down to 2 for my led? My crappy diagram of what i am trying to build is bellow. if anyone knows a better method for what i am buildin let me know though i allready have my switch and leds so they will have to work.





also, will these resistors get warm enough i will need a small fan blowing on them?
at www.mouser.com which connector is it that will plug directly in to my bigger powersupply plug?
what is the best way to connect my fans to the setup above what i can get at that site.

Thanks for all the help!!!

[xBillx]

Instead of using resistors to slow your fans, you should just wire up some switches that let you choose between having 12 and 7 volts across the fan's input. You can run the fan off 12V by using the +12V and GND wires from the PSU, and 7V using the +12V and +5V wires (12-5=7V)
here is a diagram of what i mean.

[kidsony]

thanks alot xbillx! what is the easiest way to wire a 7volt indicator led? what is the connector that connects to my ps plug calles at www.mouser.com

Thanks

[xBillx]

Actually, here, just check this out, it is a tutorial to build pretty much exactly what you want.

Fanbus.com tutorial

Hope that helps. Let me know if you have any other questions about it.

EDIT: you might just want to go to www.fanbus.com and check out all the different schematics and tutorials there, there are other ones besides what i just linked. Oh, and make sure you post some pictures for us if you start building your fanbus.