the heart of this project is a) hooking up a sensor to arduino analog input and b) programming with the if...else statement.
this particular project demonstrates a computer cooling system to maintain certain temperature within a computer tower.
i used the following items and ill explain each later. some aren't needed or can be substituted.
Arduino uno (the programming is so simple just about any arduino or other microcontroller will work)
a 9 volt clip if you don't want to power the arduino via computer
an Atx power supply
jumpers and alligator clips (alligator clips just for testing)
MintDuino kit (suggested for its built in stuff, totally not needed usually)
a thermosister (mine came with the arduino ultimate kit)
usb cable for arduino
I used the seeed studio relay sheild, other things work too
A fan or peltier device
a box to cool (my desktop computer)
the box motherboard/cpu (as something that gets hot)
LCD display (for pizazz)
a 16 pin header (to solder to LCD)
an ide cable or a floppy cable, etc. to extend lcd
wire for extending things
the Arduino IDE software and drivers
multi-meter for testing
a wire wrap tool or soldering iron
small flat-head screwdriver for relay shield
any other tools you feel are handy for this stuff
pictures of materials and how to use them will come in following steps
Step 1: Power Management
somehow everything needs to be powered. recently i discovered that you can use an atx power supply (found in most desktop PCs) as a 5 volt or 12 volt power supply. When an atx power supply is plugged into a motherboard of a computer, it provides power to everything when you press the on button of the computer. this happens because the on button connects the green whire to ground, in the atx plug. you'll need to use a jumper wire or alligator clips to connect green to one of the black. now the power supply thinks it is on. you may add a switch for on/off functionality so you dont need to unplug it every time, or use the switch on the supply for this. mine didn't have one.